TY - JOUR A1 - Huck, Christina A1 - Poghossian, Arshak A1 - Wagner, Patrick A1 - Schöning, Michael Josef T1 - Combined amperometric/field-effect sensor for the detection of dissolved hydrogen JF - Sensors and actuators B: Chemical N2 - Real-time and reliable monitoring of the biogas process is crucial for a stable and efficient operation of biogas production in order to avoid digester breakdowns. The concentration of dissolved hydrogen (H₂) represents one of the key parameters for biogas process control. In this work, a one-chip integrated combined amperometric/field-effect sensor for monitoring the dissolved H₂ concentration has been developed for biogas applications. The combination of two different transducer principles might allow a more accurate and reliable measurement of dissolved H₂ as an early warning indicator of digester failures. The feasibility of the approach has been demonstrated by simultaneous amperometric/field-effect measurements of dissolved H₂ concentrations in electrolyte solutions. Both, the amperometric and the field-effect transducer show a linear response behaviour in the H₂ concentration range from 0.1 to 3% (v/v) with a slope of 198.4 ± 13.7 nA/% (v/v) and 14.9 ± 0.5 mV/% (v/v), respectively. Y1 - 2012 U6 - http://dx.doi.org/10.1016/j.snb.2012.10.050 SN - 0925-4005 N1 - Part of special issue "Selected Papers from the 14th International Meeting on Chemical Sensors" VL - 187 SP - 168 EP - 173 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Murib, M. S. A1 - Grinsven, B. van A1 - Grieten, L. A1 - Janssens, S. D. A1 - Vermeeren, V. A1 - Eersels, K. A1 - Broeders, J. A1 - Ameloot, M. A1 - Michiels, L. A1 - Ceuninck, W. De A1 - Haenen, K. A1 - Schöning, Michael Josef A1 - Wagner, Patrick T1 - Electronic monitoring of chemical DNA denaturation on nanocrystalline diamond electrodes with different molarities and flow rates JF - Physica Status Solidi (A). Vol. 210 (2013), iss. 5 Y1 - 2013 SN - 0031-8965 SP - 911 EP - 917 PB - Wiley-VCH CY - Berlin ER - TY - JOUR A1 - Bohrn, Ulrich A1 - Mucha, Andreas A1 - Werner, Frederik A1 - Trattner, Barbara A1 - Bäcker, Matthias A1 - Krumbe, Christoph A1 - Schienle, Meinrad A1 - Stütz, Evamaria A1 - Schmitt-Landsiedel, Doris A1 - Fleischer, Maximilian A1 - Wagner, Patrick A1 - Schöning, Michael Josef T1 - A critical comparison of cell-based sensor systems for the detection of Cr (VI) in aquatic environment JF - Sensors and actuators. B: Chemical Y1 - 2013 SN - 1873-3077 (E-Journal); 0925-4005 (Print) VL - Vol. 182 SP - 58 EP - 65 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Kramer, Friederike A1 - Halamkova, Lenka A1 - Poghossian, Arshak A1 - Schöning, Michael Josef A1 - Katz, Evgeny A1 - Halamek, Jan T1 - Biocatalytic analysis of biomarkers for forensic identification of ethnicity between Caucasian and African American JF - The analyst. August 2013 Y1 - 2013 SN - 1364-5528 (E-Journal); 0003-2654 (Print) VL - Vol. 138 SP - 6251 EP - 6257 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Schusser, Sebastian A1 - Menzel, S. A1 - Bäcker, Matthias A1 - Leinhos, Marcel A1 - Poghossian, Arshak A1 - Wagner, P. A1 - Schöning, Michael Josef T1 - Degradation of thin poly(lactic acid) films: characterization by capacitance-voltage, atomic force microscopy, scanning electron microscopy and contact-angle measurements JF - Electrochimica Acta Y1 - 2013 SN - 1873-3859 (E-Journal); 0013-4686 (Print) VL - Vol. 113 SP - 779 EP - 784 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Iken, Heiko A1 - Ahlborn, K. A1 - Gerlach, F. A1 - Vonau, W. A1 - Zander, W. A1 - Schubert, J. A1 - Schöning, Michael Josef T1 - Development of redox glasses and subsequent processing by means of pulsed laser deposition for realizing silicon-based thin-film sensors JF - Electrochimica acta Y1 - 2013 SN - 1873-3859 (E-Journal); 0013-4686 (Print) SP - Available online 30.8.2013 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Bandodkar, Amay J. A1 - Molinnus, Denise A1 - Mirza, Omar A1 - Guinovart, Tomas A1 - Windmiller, Joshua R. A1 - Valdes-Ramirez, Gabriela A1 - Andrade, Francisco J. A1 - Schöning, Michael Josef A1 - Wang, Joseph T1 - Epidermal tattoo potentiometric sodium sensors with wireless signal transduction for continuous non-invasive sweat monitoring JF - Biosensors and bioelectronics N2 - This article describes the fabrication, characterization and application of an epidermal temporary-transfer tattoo-based potentiometric sensor, coupled with a miniaturized wearable wireless transceiver, for real-time monitoring of sodium in the human perspiration. Sodium excreted during perspiration is an excellent marker for electrolyte imbalance and provides valuable information regarding an individual's physical and mental wellbeing. The realization of the new skin-worn non-invasive tattoo-like sensing device has been realized by amalgamating several state-of-the-art thick film, laser printing, solid-state potentiometry, fluidics and wireless technologies. The resulting tattoo-based potentiometric sodium sensor displays a rapid near-Nernstian response with negligible carryover effects, and good resiliency against various mechanical deformations experienced by the human epidermis. On-body testing of the tattoo sensor coupled to a wireless transceiver during exercise activity demonstrated its ability to continuously monitor sweat sodium dynamics. The real-time sweat sodium concentration was transmitted wirelessly via a body-worn transceiver from the sodium tattoo sensor to a notebook while the subjects perspired on a stationary cycle. The favorable analytical performance along with the wearable nature of the wireless transceiver makes the new epidermal potentiometric sensing system attractive for continuous monitoring the sodium dynamics in human perspiration during diverse activities relevant to the healthcare, fitness, military, healthcare and skin-care domains. Y1 - 2014 U6 - http://dx.doi.org/10.1016/j.bios.2013.11.039 SN - 1873-4235 (E-Journal); 0956-5663 (Print) VL - 54 SP - 603 EP - 609 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Reisert, Steffen A1 - Geissler, Hanno A1 - Flörke, Rudolf A1 - Weiler, Christian A1 - Wagner, Patrick A1 - Schöning, Michael Josef T1 - Characterisation of aseptic sterilisation processes using an electronic nose JF - International journal of nanotechnology Y1 - 2013 SN - 1475-7435 (Print) 7141-8151 (Online) VL - Vol. 10 IS - No. 5-7 SP - 470 EP - 484 PB - Inderscience Enterprises CY - Genève ER - TY - JOUR A1 - Miyamoto, Ko-ichiro A1 - Hirayama, Yuji A1 - Wagner, Torsten A1 - Schöning, Michael Josef A1 - Yoshinobu, Tatsuo T1 - Visualization of enzymatic reaction in a microfluidic channel using chemical imaging sensor JF - Electrochimica acta Y1 - 2013 SN - 1873-3859 (E-Journal); 0013-4686 (Print) SP - Publ. online PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Bäcker, Matthias A1 - Schusser, Sebastian A1 - Poghossian, Arshak A1 - Schöning, Michael Josef T1 - Degradationsverhalten bioabbaubarer Polymere : siliziumbasierte Sensorik zur Überwachung JF - GIT Labor-Fachzeitschrift Y1 - 2013 SN - 0016-3538 SP - 32 EP - 33 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Buniatyan, V. A1 - Huck, Christina A1 - Poghossian, Arshak A1 - Aroutiounian, V. M. A1 - Schöning, Michael Josef T1 - BaxSr1-x TiO3/pc-Si heterojunction capacitance JF - Armenian journal of physics Y1 - 2013 SN - 1829-1171 VL - 6 IS - 4 SP - 188 EP - 197 PB - National Academy of Sciences of Armenia CY - Yerevan ER - TY - JOUR A1 - Buniatyan, V. A1 - Huck, Christina A1 - Poghossian, Arshak A1 - Aroutiounian, V. M. A1 - Schöning, Michael Josef T1 - BaxSr1-x TiO3/pc-Si heterojunction JF - Armenian journal of physics Y1 - 2013 SN - 1829-1171 VL - 6 IS - 4 SP - 177 EP - 187 PB - National Academy of Sciences of Armenia CY - Yerevan ER - TY - JOUR A1 - Miyamoto, Ko-ichiro A1 - Itabashi, Akinori A1 - Wagner, Torsten A1 - Schöning, Michael Josef A1 - Yoshinobu, Tatsuo T1 - High-speed chemical imaging inside a microfluidic channel JF - Sensors and actuators. B: Chemical N2 - In this study, a high-speed chemical imaging system was developed for visualization of the interior of a microfluidic channel. A microfluidic channel was constructed on the sensor surface of the light-addressable potentiometric sensor (LAPS), on which the ion concentrations could be measured in parallel at up to 64 points illuminated by optical fibers. The temporal change of pH distribution inside the microfluidic channel was recorded at a maximum rate of 100 frames per second (fps). The high frame rate allowed visualization of moving interfaces and plugs in the channel even at a flow velocity of 111 mm/s, which suggests the feasibility of plug-based microfluidic devices for flow-injection analysis (FIA). Y1 - 2014 U6 - http://dx.doi.org/10.1016/j.snb.2013.12.090 SN - 1873-3077 (E-Journal); 0925-4005 (Print) VL - 194 SP - 521 EP - 527 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Moseley, Fiona A1 - Halamek, Jan A1 - Kramer, Friederike A1 - Poghossian, Arshak A1 - Schöning, Michael Josef A1 - Katz, Evgeny T1 - An enzyme-based reversible CNOT logic gate realized in a flow system JF - Analyst N2 - An enzyme system organized in a flow device was used to mimic a reversible Controlled NOT (CNOT) gate with two input and two output signals. Reversible conversion of NAD⁺ and NADH cofactors was used to perform a XOR logic operation, while biocatalytic hydrolysis of p-nitrophenyl phosphate resulted in an Identity operation working in parallel. The first biomolecular realization of a CNOT gate is promising for integration into complex biomolecular networks and future biosensor/biomedical applications. Y1 - 2014 U6 - http://dx.doi.org/10.1039/C4AN00133H SN - 1364-5528 (E-Journal) ; 0003-2654 (Print) VL - 139 IS - 8 SP - 1839 EP - 1842 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Leinhos, Marcel A1 - Schusser, Sebastian A1 - Bäcker, Matthias A1 - Poghossian, Arshak A1 - Schöning, Michael Josef T1 - Micromachined multi-parameter sensor chip for the control of polymer-degradation medium JF - Physica Status Solidi (A) : special issue on engineering and functional interfaces N2 - It is well known that the degradation environment can strongly influence the biodegradability and kinetics of biodegradation processes of polymers. Therefore, besides the monitoring of the degradation process, it is also necessary to control the medium in which the degradation takes place. In this work, a micromachined multi-parameter sensor chip for the control of the polymer-degradation medium has been developed. The chip combines a capacitive field-effect pH sensor, a four-electrode electrolyte-conductivity sensor and a thin-film Pt-temperature sensor. The results of characterization of individual sensors are presented. In addition, the multi-parameter sensor chip together with an impedimetric polymer-degradation sensor was simultaneously characterized in degradation solutions with different pH and electrolyte conductivity. The obtained results demonstrate the feasibility of the multi-parameter sensor chip for the control of the polymer-degradation medium. Y1 - 2014 U6 - http://dx.doi.org/10.1002/pssa.201330364 SN - 1521-396X (E-Journal); 1862-6319 (E-Journal); 0031-8965 (Print); 1862-6300 (Print) VL - 211 IS - 6 SP - 1346 EP - 1351 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Huck, Christina A1 - Poghossian, Arshak A1 - Kerroumi, Iman A1 - Schusser, Sebastian A1 - Bäcker, Matthias A1 - Zander, Willi A1 - Schubert, Jürgen A1 - Buniatyan, Vahe V. A1 - Martirosyan, Norayr W. A1 - Wagner, Patrick A1 - Schöning, Michael Josef T1 - Multiparameter sensor chip with Barium Strontium Titanate as multipurpose material JF - Electroanalysis N2 - It is well known that biochemical and biotechnological processes are strongly dependent and affected by a variety of physico-chemical parameters such as pH value, temperature, pressure and electrolyte conductivity. Therefore, these quantities have to be monitored or controlled in order to guarantee a stable process operation, optimization and high yield. In this work, a sensor chip for the multiparameter detection of three physico-chemical parameters such as electrolyte conductivity, pH and temperature is realized using barium strontium titanate (BST) as multipurpose material. The chip integrates a capacitively coupled four-electrode electrolyte-conductivity sensor, a capacitive field-effect pH sensor and a thin-film Pt-temperature sensor. Due to the multifunctional properties of BST, it is utilized as final outermost coating layer of the processed sensor chip and serves as passivation and protection layer as well as pH-sensitive transducer material at the same time. The results of testing of the individual sensors of the developed multiparameter sensor chip are presented. In addition, a quasi-simultaneous multiparameter characterization of the sensor chip in buffer solutions with different pH value and electrolyte conductivity is performed. To study the sensor behavior and the suitability of BST as multifunctional material under harsh environmental conditions, the sensor chip was exemplarily tested in a biogas digestate. Y1 - 2014 U6 - http://dx.doi.org/10.1002/elan.201400076 SN - 1521-4109 (E-Journal); 1040-0397 (Print) VL - 26 IS - 5 SP - 980 EP - 987 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Bäcker, Matthias A1 - Kramer, F. A1 - Huck, Christina A1 - Poghossian, Arshak A1 - Bratov, A. A1 - Abramova, N. A1 - Schöning, Michael Josef T1 - Planar and 3D interdigitated electrodes for biosensing applications: The impact of a dielectric barrier on the sensor properties JF - Physica Status Solidi (A) - Applications and Materials Science N2 - Planar and three-dimensional (3D) interdigitated electrodes (IDE) with electrode digits separated by an insulating barrier of different heights were electrochemically characterized and compared in terms of their sensing properties. Due to the impact of the surface resistance, both types of IDE structures display a non-linear behavior in low-ionic strength solutions. The experimental data were fitted to an electrical equivalent circuit and interpreted taking into account the surface-charge-governed properties. The effect of a charged polyelectrolyte layer electrostatically assembled onto the sensor surface on the surface resistance in solutions with different KCl concentration is studied. In case of the same electrode footprint, 3D-IDEs show a larger cell constant and a higher sensitivity to molecular adsorption than that of planar IDEs. The obtained results demonstrate the potential of 3D-IDEs as a new transducer structure for a direct label-free sensing of charged molecules. Y1 - 2014 U6 - http://dx.doi.org/10.1002/pssa.201330416 SN - 1521-396X (E-Journal); 1862-6319 (E-Journal); 0031-8965 (Print); 1862-6300 (Print) VL - 211 IS - 6 SP - 1357 EP - 1363 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Huck, Christina A1 - Poghossian, Arshak A1 - Bäcker, Matthias A1 - Chaudhuri, S. A1 - Zander, W. A1 - Schubert, J. A1 - Begoyan, V. K. A1 - Buniatyan, V. V. A1 - Wagner, P. A1 - Schöning, Michael Josef T1 - Capacitively coupled electrolyte-conductivity sensor based on high-k material of barium strontium titanate JF - Sensors and actuators. B: Chemical Y1 - 2014 U6 - http://dx.doi.org/10.1016/j.snb.2014.02.103 SN - 1873-3077 (E-Journal); 0925-4005 (Print) IS - 198 SP - 102 EP - 109 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Schöning, Michael Josef A1 - Biselli, Manfred A1 - Selmer, Thorsten A1 - Öhlschläger, Peter A1 - Baumann, Marcus A1 - Förster, Arnold A1 - Poghossian, Arshak T1 - Forschung „zwischen“ den Disziplinen: das Institut für Nano- und Biotechnologien JF - Analytik news : das Online-Labormagazin für Labor und Analytik N2 - "Biologie trifft Mikroelektronik", das Motto des Instituts für Nano- und Biotechnologien (INB) an der FH Aachen, unterstreicht die zunehmende Bedeutung interdisziplinär geprägter Forschungsaktivitäten. Der thematische Zusammenschluss grundständiger Disziplinen, wie die Physik, Elektrotechnik, Chemie, Biologie sowie die Materialwissenschaften, lässt neue Forschungsgebiete entstehen, ein herausragendes Beispiel hierfür ist die Nanotechnologie: Hier werden neue Werkstoffe und Materialien entwickelt, einzelne Nanopartikel oder Moleküle und deren Wechselwirkung untersucht oder Schichtstrukturen im Nanometerbereich aufgebaut, die neue und vorher nicht bekannte Eigenschaften hervorbringen. Vor diesem Hintergrund bündelt das im Jahre 2006 gegründete INB die an der FH Aachen vorhandenen Kompetenzen von derzeit insgesamt sieben Laboratorien auf den Gebieten der Halbleitertechnik und Nanoelektronik, Nanostrukturen und DNA-Sensorik, der Chemo- und Biosensorik, der Enzymtechnologie, der Mikrobiologie und Pflanzenbiotechnologie, der Zellkulturtechnik, sowie der Roten Biotechnologie synergetisch. In der Nano- und Biotechnologie steckt außergewöhnliches Potenzial! Nicht zuletzt deshalb stellen sich die Forscher der Herausforderung, in diesem Bereich gemeinsam zu forschen und Schnittstellen zu nutzen, um so bei der Gestaltung neuartiger Ideen und Produkte mitzuwirken, die zukünftig unser alltägliches Leben verändern werden. Im Folgenden werden die verschiedenen Forschungsbereiche kurz zusammenfassend vorgestellt und vorhandene Interaktionen anhand von exemplarisch ausgewählten, aktuellen Forschungsprojekten skizziert. Y1 - 2012 VL - Publ. online PB - Dr. Beyer Internet-Beratung CY - Ober-Ramstadt ER - TY - JOUR A1 - Wu, Chunsheng A1 - Bronder, Thomas A1 - Poghossian, Arshak A1 - Werner, Frederik A1 - Bäcker, Matthias A1 - Schöning, Michael Josef T1 - Label-free electrical detection of DNA with a multi-spot LAPS: First step towards light-addressable DNA chips JF - Physica status solidi A : Applications and materials science N2 - A multi-spot (4 × 4 spots) light-addressable potentiometric sensor (MLAPS) consisting of an Al–p-Si–SiO2 structure has been applied for the label-free electrical detection of DNA (deoxyribonucleic acid) immobilization and hybridization by the intrinsic molecular charge for the first time. Single-stranded probe ssDNA molecules (20 bases) were covalently immobilized onto the silanized SiO2 gate surface. The unspecific adsorption of mismatch ssDNA on the MLAPS gate surface was blocked by bovine serum albumin molecules. To reduce the screening effect and to achieve a high sensor signal, the measurements were performed in a low ionic-strength solution. The photocurrent–voltage (I–V) curves were simultaneously recorded on all 16 spots after each surface functionalization step. Large shifts of I–V curves of 25 mV were registered after the DNA immobilization and hybridization event. In contrast, a small potential shift (∼5 mV) was observed in case of mismatch ssDNA, revealing good specificity of the sensor. The obtained results demonstrate the potential of the MLAPS as promising transducer platform for the multi-spot label-free electrical detection of DNA molecules by their intrinsic molecular charge. Y1 - 2014 U6 - http://dx.doi.org/10.1002/pssa.201330442 SN - 1521-396X (E-Journal); 1862-6319 (E-Journal); 0031-8965 (Print); 1862-6300 (Print) VL - 211 IS - 6 SP - 1423 EP - 1428 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Guo, Yuanyuan A1 - Seki, Kosuke A1 - Miyamoto, Ko-ichiro A1 - Wagner, Torsten A1 - Schöning, Michael Josef A1 - Yoshinobu, Tatsuo T1 - Novel photoexcitation method for light-addressable potentiometric sensor with higher spatial resolution JF - Applied physics express : APEX N2 - A novel photoexcitation method for the light-addressable potentiometric sensor (LAPS) is proposed to achieve a higher spatial resolution of chemical images. The proposed method employs a combined light source that consists of a modulated light probe, which generates the alternating photocurrent signal, and a ring of constant illumination surrounding it. The constant illumination generates a sheath of carriers with increased concentration which suppresses the spread of photocarriers by enhanced recombination. A device simulation was carried out to verify the effect of constant illumination on the spatial resolution, which demonstrated that a higher spatial resolution can be obtained. Y1 - 2014 U6 - http://dx.doi.org/10.7567/APEX.7.067301 SN - 1882-0786 (E-Journa); 1882-0778 (Print) VL - 7 IS - 6 SP - 067301-4 PB - IOP CY - Bristol ER - TY - JOUR A1 - Wagner, Patrick A1 - Doll, Theodor A1 - Schöning, Michael Josef T1 - Engineering of functional interfaces / Patrick Wagner ; Theodor Doll ; Michael J. Schöning (eds.) JF - Physica status solidi (A) : Applications and materials science Y1 - 2014 U6 - http://dx.doi.org/10.1002/pssa.201470241 SN - 1521-396X (E-Book); 1862-6319 (E-Book); 0031-8965 (Print); 1862-6300 (Print) VL - 211 IS - 6 SP - 1339 EP - 1339 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Riedel, Marc A1 - Kartchemnik, Julia A1 - Schöning, Michael Josef A1 - Lisdat, Fred T1 - Impedimetric DNA detection – steps forward to sensorial application JF - Analytical chemistry N2 - This study describes a label-free impedimetric sensor based on short ssDNA recognition elements for the detection of hybridization events. We concentrate on the elucidation of the influence of target length and recognition sequence position on the sensorial performance. The impedimetric measurements are performed in the presence of the redox system ferri-/ferrocyanide and show an increase in charge transfer resistance upon hybridization of ssDNA to the sensor surface. Investigations on the impedimetric signal stability demonstrate a clear influence of the buffers used during the sensor preparation and the choice of the passivating mercaptoalcanol compound. A stable sensor system has been developed, enabling a reproducible detection of 25mer target DNA in the low nanomolar range. After hybridization, a sensor regeneration can be reached with deionized water by adjustment of effective convection conditions, ensuring a sensor reusability. By investigations of longer targets with overhangs exposed to the solution, we can demonstrate applicability of the impedimetric detection for longer ssDNA. However, a decreasing charge transfer resistance change (ΔRct) is found by extending the overhang. As a strategy to increase the impedance change for longer target strands, the position of the recognition sequence can be designed in a way that a small overhang is exposed to the electrode surface. This is found to result in an increase in the relative Rct change. These results suggest that DNA and consequently negative charge near the electrode possess a larger impact on the impedimetric signal than DNA further away. Y1 - 2014 U6 - http://dx.doi.org/10.1021/ac501800q SN - 1520-6882 (E-Journal); 0003-2700 (Print); 0096-4484 (Print) VL - 86 (2014) IS - 15 SP - 7867 EP - 7874 PB - ACS Publications CY - Columbus ER - TY - JOUR A1 - Guo, Yuanyuan A1 - Miyamoto, Ko-ichiro A1 - Wagner, Torsten A1 - Schöning, Michael Josef A1 - Yoshinobu, Tatsuo T1 - Device simulation of the light-addressable potentiometric sensor for the investigation of the spatial resolution JF - Sensors and actuators B: Chemical N2 - As a semiconductor-based electrochemical sensor, the light-addressable potentiometric sensor (LAPS) can realize two dimensional visualization of (bio-)chemical reactions at the sensor surface addressed by localized illumination. Thanks to this imaging capability, various applications in biochemical and biomedical fields are expected, for which the spatial resolution is critically significant. In this study, therefore, the spatial resolution of the LAPS was investigated in detail based on the device simulation. By calculating the spatiotemporal change of the distributions of electrons and holes inside the semiconductor layer in response to a modulated illumination, the photocurrent response as well as the spatial resolution was obtained as a function of various parameters such as the thickness of the Si substrate, the doping concentration, the wavelength and the intensity of illumination. The simulation results verified that both thinning the semiconductor substrate and increasing the doping concentration could improve the spatial resolution, which were in good agreement with known experimental results and theoretical analysis. More importantly, new findings of interests were also obtained. As for the dependence on the wavelength of illumination, it was found that the known dependence was not always the case. When the Si substrate was thick, a longer wavelength resulted in a higher spatial resolution which was known by experiments. When the Si substrate was thin, however, a longer wavelength of light resulted in a lower spatial resolution. This finding was explained as an effect of raised concentration of carriers, which reduced the thickness of the space charge region. The device simulation was found to be helpful to understand the relationship between the spatial resolution and device parameters, to understand the physics behind it, and to optimize the device structure and measurement conditions for realizing higher performance of chemical imaging systems. Y1 - 2014 U6 - http://dx.doi.org/10.1016/j.snb.2014.08.016 SN - 1873-3077 (E-Journal); 0925-4005 (Print) VL - 204 SP - 659 EP - 665 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Reisert, Steffen A1 - Geissler, H. A1 - Weiler, C. A1 - Wagner, P. A1 - Schöning, Michael Josef T1 - Multiple sensor-type system for monitoring the microbicidal effectiveness of aseptic sterilisation processes JF - Food control N2 - The present work describes a novel multiple sensor-type system for the real-time analysis of aseptic sterilisation processes employing gaseous hydrogen peroxide (H2O2) as a sterilant. The inactivation kinetics of Bacillus atrophaeus by gaseous H2O2 have been investigated by means of a methodical calibration experiment, taking into account the process variables H2O2 concentration, humidity and gas temperature. It has been found that the microbicidal effectiveness at H2O2 concentrations above 2% v/v is largely determined by the concentration itself, while at lower H2O2 concentrations, the gas temperature and humidity play a leading role. Furthermore, the responses of different types of gas sensors towards the influencing factors of the sterilisation process have been analysed within the same experiment. Based on a correlation established between the inactivation kinetics and the sensor responses, a calorimetric H2O2 sensor and a metal-oxide semiconductor (MOX) sensor have been identified as possible candidates for monitoring the microbicidal effectiveness of aseptic sterilisation processes employing gaseous H2O2. Therefore, two linear models that describe the relationship between sensor response and microbicidal effectiveness have been proposed. Y1 - 2015 U6 - http://dx.doi.org/10.1016/j.foodcont.2014.07.063 SN - 1873-7129 (E-Journal); 0956-7135 (Print) VL - 47 SP - 615 EP - 622 ER - TY - JOUR A1 - Khaydukova, M. M. A1 - Zadorozhnaya, O. A. A1 - Kirsanov, D. O. A1 - Iken, Heiko A1 - Rolka, David A1 - Schöning, Michael Josef A1 - Babain, V. A. A1 - Vlasov, Yu. G. A1 - Legin, A. V. T1 - Multivariate processing of atomic-force microscopy images for detection of the response of plasticized polymeric membranes JF - Russian journal of applied chemistry N2 - The possibility of using the atomic-force microscopy as a method for detection of the analytical signal from plasticized polymeric sensor membranes was analyzed. The surfaces of cadmium-selective membranes based on two polymeric matrices were examined. The digital images were processed with multivariate image analysis techniques. A correlation was found between the surface profile of an ion-selective membrane and the concentration of the ion in solution. Y1 - 2014 U6 - http://dx.doi.org/10.1134/S1070427214030112 SN - 1608-3296 (E-Journal); 1070-4272 (Print) VL - 87 IS - 3 SP - 307 EP - 314 PB - Springer CY - Dordrecht ER - TY - JOUR A1 - Bäcker, Matthias A1 - Schusser, Sebastian A1 - Poghossian, Arshak A1 - Schöning, Michael Josef T1 - Multi-Parametererfassung mit siliziumbasiertem Sensorchip: Aus Drei mach Eins JF - GIT Labor-Fachzeitschrift Y1 - 2014 SN - 0016-3538 IS - 2 SP - 28 EP - 30 PB - Wiley ER - TY - JOUR A1 - Murib, Mohammed Sharif A1 - Yeap, Weng-Siang A1 - Martens, Daan A1 - Bienstman, Peter A1 - Ceuninck, Ward de A1 - Grinsven, Bart van A1 - Schöning, Michael Josef A1 - Michiels, Luc A1 - Haenen, Ken A1 - Ameloot, Marcel A1 - Serpengüzel, Ali A1 - Wagner, Patrick T1 - Photonic detection and characterization of DNA using sapphire microspheres JF - Journal of biomedical optics N2 - A microcavity-based deoxyribonucleic acid (DNA) optical biosensor is demonstrated for the first time using synthetic sapphire for the optical cavity. Transmitted and elastic scattering intensity at 1510 nm are analyzed from a sapphire microsphere (radius 500  μm, refractive index 1.77) on an optical fiber half coupler. The 0.43 nm angular mode spacing of the resonances correlates well with the optical size of the sapphire sphere. Probe DNA consisting of a 36-mer fragment was covalently immobilized on a sapphire microsphere and hybridized with a 29-mer target DNA. Whispering gallery modes (WGMs) were monitored before the sapphire was functionalized with DNA and after it was functionalized with single-stranded DNA (ssDNA) and double-stranded DNA (dsDNA). The shift in WGMs from the surface modification with DNA was measured and correlated well with the estimated thickness of the add-on DNA layer. It is shown that ssDNA is more uniformly oriented on the sapphire surface than dsDNA. In addition, it is shown that functionalization of the sapphire spherical surface with DNA does not affect the quality factor (Q≈104) of the sapphire microspheres. The use of sapphire is especially interesting because this material is chemically resilient, biocompatible, and widely used for medical implants. Y1 - 2014 U6 - http://dx.doi.org/10.1117/1.JBO.19.9.097006 SN - 1560-2281 (E-Journal); 1083-3668 (Print) VL - 19 IS - 9 SP - 097006 PB - SPIE CY - Bellingham ER - TY - JOUR A1 - Yoshinobu, Tatsuo A1 - Miyamoto, Ko-ichiro A1 - Wagner, Torsten A1 - Schöning, Michael Josef T1 - Recent developments of chemical imaging sensor systems based on the principle of the light-addressable potentiometric sensor JF - Sensors and actuators B: Chemical N2 - The light-addressable potentiometric sensor (LAPS) is an electrochemical sensor with a field-effect structure to detect the variation of the Nernst potential at its sensor surface, the measured area on which is defined by illumination. Thanks to this light-addressability, the LAPS can be applied to chemical imaging sensor systems, which can visualize the two-dimensional distribution of a particular target ion on the sensor surface. Chemical imaging sensor systems are expected to be useful for analysis of reaction and diffusion in various electrochemical and biological samples. Recent developments of LAPS-based chemical imaging sensor systems, in terms of the spatial resolution, measurement speed, image quality, miniaturization and integration with microfluidic devices, are summarized and discussed. Y1 - 2015 U6 - http://dx.doi.org/10.1016/j.snb.2014.09.002 SN - 1873-3077 (E-Journal); 0925-4005 (Print) VL - 207, Part B SP - 926 EP - 932 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Siqueira, Jose R. A1 - Molinnus, Denise A1 - Beging, Stefan A1 - Schöning, Michael Josef T1 - Incorporating a hybrid urease-carbon nanotubes sensitive nanofilm on capacitive field-effect sensors for urea detection JF - Analytical chemistry N2 - The ideal combination among biomolecules and nanomaterials is the key for reaching biosensing units with high sensitivity. The challenge, however, is to find out a stable and sensitive film architecture that can be incorporated on the sensor’s surface. In this paper, we report on the benefits of incorporating a layer-by-layer (LbL) nanofilm of polyamidoamine (PAMAM) dendrimer and carbon nanotubes (CNTs) on capacitive electrolyte-insulator-semiconductor (EIS) field-effect sensors for detecting urea. Three sensor arrangements were studied in order to investigate the adequate film architecture, involving the LbL film with the enzyme urease: (i) urease immobilized directly onto a bare EIS [EIS-urease] sensor; (ii) urease atop the LbL film over the EIS [EIS-(PAMAM/CNT)-urease] sensor; and (iii) urease sandwiched between the LbL film and another CNT layer [EIS-(PAMAM/CNT)-urease-CNT]. The surface morphology of all three urea-based EIS biosensors was investigated by atomic force microscopy (AFM), while the biosensing abilities were studied by means of capacitance–voltage (C/V) and dynamic constant-capacitance (ConCap) measureaments at urea concentrations ranging from 0.1 mM to 100 mM. The EIS-urease and EIS-(PAMAM/CNT)-urease sensors showed similar sensitivity (∼18 mV/decade) and a nonregular signal behavior as the urea concentration increased. On the other hand, the EIS-(PAMAM/CNT)-urease-CNT sensor exhibited a superior output signal performance and higher sensitivity of about 33 mV/decade. The presence of the additional CNT layer was decisive to achieve a urea based EIS sensor with enhanced properties. Such sensitive architecture demonstrates that the incorporation of an adequate hybrid enzyme-nanofilm as sensing unit opens new prospects for biosensing applications using the field-effect sensor platform. Y1 - 2014 U6 - http://dx.doi.org/10.1021/ac500458s SN - 1520-6882 (E-Journal); 0003-2700 (Print); 0096-4484 (Print) VL - 86 IS - 11 SP - 5370 EP - 5375 PB - ACS Publications CY - Columbus ER - TY - JOUR A1 - Poghossian, Arshak A1 - Bäcker, Matthias A1 - Mayer, Dirk A1 - Schöning, Michael Josef T1 - Gating capacitive field-effect sensors by the charge of nanoparticle/molecule hybrids JF - Nanoscale Y1 - 2015 U6 - http://dx.doi.org/10.1039/C4NR05987E SN - 2040-3372 (E-Journal); 2040-3364 (Print) SP - 1023 EP - 1031 PB - Royal Society of Chemistry (RSC) CY - Cambridge ER - TY - JOUR A1 - Schusser, Sebastian A1 - Poghossian, Arshak A1 - Bäcker, Matthias A1 - Krischer, M. A1 - Leinhos, Marcel A1 - Wagner, P. A1 - Schöning, Michael Josef T1 - An application of field-effect sensors for in-situ monitoring of degradation of biopolymers JF - Sensors and actuators B: Chemical N2 - The characterization of the degradation kinetics of biodegradable polymers is mandatory with regard to their proper application. In the present work, polymer-modified electrolyte–insulator–semiconductor (PMEIS) field-effect sensors have been applied for in-situ monitoring of the pH-dependent degradation kinetics of the commercially available biopolymer poly(d,l-lactic acid) (PDLLA) in buffer solutions from pH 3 to pH 13. PDLLA films of 500 nm thickness were deposited on the surface of an Al–p-Si–SiO2–Ta2O5 structure from a polymer solution by means of spin-coating method. The PMEIS sensor is, in principle, capable to detect any changes in bulk, surface and interface properties of the polymer induced by degradation processes. A faster degradation has been observed for PDLLA films exposed to alkaline solutions (pH 9, pH 11 and pH 13). Y1 - 2015 U6 - http://dx.doi.org/10.1016/j.snb.2014.10.058 SN - 1873-3077 (E-Journal); 0925-4005 (Print) VL - 207, Part B SP - 954 EP - 959 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Guo, Yuanyuan A1 - Seki, Kosuke A1 - Miyamoto, Ko-ichiro A1 - Wagner, Torsten A1 - Schöning, Michael Josef A1 - Yoshinobu, Tatsuo T1 - Device simulation of the light-addressable potentiometric sensor with a novel photoexcitation method for a higher spatial resolution JF - Procedia Engineering N2 - A novel photoexcitation method for the light-addressable potentiometric sensor (LAPS) realized a higher spatial resolution of chemical imaging. In this method, a modulated light probe, which generates the alternating photocurrent signal, is surrounded by a ring of constant light, which suppresses the lateral diffusion of photocarriers by enhancing recombination. A device simulation verified that a higher spatial resolution could be obtained by adjusting the gap between the modulated and constant light. It was also found that a higher intensity and a longer wavelength of constant light was more effective. However, there exists a tradeoff between the spatial resolution and the amplitude of the photocurrent, and thus, the signal-to-noise ratio. A tilted incidence of constant light was applied, which could achieve even higher resolution with a smaller loss of photocurrent. KW - Light-addressable Potentiometric Sensor KW - novel photoexcitation method KW - tilted constant illumination KW - spatial resolution Y1 - 2014 U6 - http://dx.doi.org/10.1016/j.proeng.2014.11.369 SN - 1877-7058 N1 - EUROSENSORS 2014 ; European Conference on Solid-State Transducers <28, 2014> VL - 87 SP - 456 EP - 459 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Miyamoto, K. A1 - Seki, K. A1 - Wagner, Torsten A1 - Schöning, Michael Josef A1 - Yoshinobu, T. T1 - Enhancement of the spatial resolution of the chemical imaging sensor by a hybrid fiber-optic illumination JF - Procedia Engineering N2 - The chemical imaging sensor, which is based on the principle of the light-addressable potentiometric sensor (LAPS), is a powerful tool to visualize the spatial distribution of chemical species on the sensor surface. The spatial resolution of this sensor depends on the diffusion of photocarriers excited by a modulated light. In this study, a novel hybrid fiber-optic illumination was developed to enhance the spatial resolution. It consists of a modulated light probe to generate a photocurrent signal and a ring of constant light, which suppresses the lateral diffusion of minority carriers excited by the modulated light. It is demonstrated that the spatial resolution was improved from 92 μm to 68 μm. Y1 - 2014 U6 - http://dx.doi.org/10.1016/j.proeng.2014.11.563 SN - 1877-7058 N1 - EUROSENSORS 2014 ; European Conference on Solid-State Transducers <28, 2014> VL - 87 SP - 612 EP - 615 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Bronder, Thomas A1 - Wu, Chunsheng A1 - Poghossian, Arshak A1 - Werner, Frederik A1 - Keusgen, M. A1 - Schöning, Michael Josef T1 - Label-free detection of DNA hybridization with light-addressable potentiometric sensors: comparison of various DNA-immobilization strategies JF - Procedia Engineering N2 - Light-addressable potentiometric sensors (LAPS) consisting of a p-Si-SiO2 and p-Si-SiO2-Au structure, respectively, have been tested for a label-free electrical detection of DNA (deoxyribonucleic acid) hybridization. Three different strategies for immobilizing single-stranded probe DNA (ssDNA) molecules on a LAPS surface have been studied and compared: (a) immobilization of thiol-modified ssDNA on the patterned Au surface via gold-thiol bond, (b) covalent immobilization of amino-modified ssDNA onto the SiO2 surface functionalized with 3-aminopropyltriethoxysilane and (c) layer-by-layer adsorption of negatively charged ssDNA on a positively charged weak polyelectrolyte layer of poly(allylamine hydrochloride). KW - LAPS KW - lable-free detection KW - DNA hybridization KW - field-effect sensor Y1 - 2014 U6 - http://dx.doi.org/10.1016/j.proeng.2014.11.647 SN - 1877-7058 N1 - EUROSENSORS 2014 ; European Conference on Solid-State Transducers <28, 2014> VL - 87 SP - 755 EP - 758 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Huck, Christina A1 - Poghossian, Arshak A1 - Bäcker, Matthias A1 - Reisert, Steffen A1 - Schubert, J. A1 - Zander, W. A1 - Begoyan, V. K. A1 - Buniatyan, V. V. A1 - Schöning, Michael Josef T1 - Chemical sensors based on a high-k perovskite oxide of barium strontium titanate JF - Procedia Engineering N2 - High-k perovskite oxide of barium strontium titanate (BST) represents a very attractive multi-functional transducer material for the development of (bio-)chemical sensors for liquids. In this work, BST films have been applied as a sensitive transducer material for a label-free detection of adsorbed charged macromolecules (positively charged polyelectrolytes) and concentration of hydrogen peroxide vapor as well as protection insulator layer for a contactless electrolyte-conductivity sensor. The experimental results of characterization of individual sensors are presented. Special emphasis is devoted towards the development of a capacitively-coupled contactless electrolyte-conductivity sensor. KW - barium strontium titanate KW - high-k material KW - contactless conductivity sensor KW - multi-functional material KW - hydrogen peroxide Y1 - 2014 U6 - http://dx.doi.org/10.1016/j.proeng.2014.11.258 SN - 1877-7058 N1 - EUROSENSORS 2014 ; European Conference on Solid-State Transducers <28, 2014> VL - 87 SP - 28 EP - 31 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Schusser, Sebastian A1 - Bäcker, Matthias A1 - Krischer, M. A1 - Wenzel, L. A1 - Leinhos, Marcel A1 - Poghossian, Arshak A1 - Biselli, Manfred A1 - Wagner, P. A1 - Schöning, Michael Josef T1 - Enzymatically catalyzed degradation of biodegradable polymers investigated by means of a semiconductor-based field-effect sensor JF - Procedia Engineering N2 - A semiconductor field-effect device has been used for an enzymatically catalyzed degradation of biopolymers for the first time. This novel technique is capable to monitor the degradation process of multiple samples in situ and in real-time. As model system, the degradation of the biopolymer poly(D, L-lactic acid) has been monitored in the degradation medium containing the enzyme lipase from Rhizomucor miehei. The obtained results demonstrate the potential of capacitive field-effect sensors for degradation studies of biodegradable polymers. KW - Field-effect sensor KW - enzymatic (bio)degradation KW - poly(d, l-lactic acid) KW - in-situ monitoring KW - impedance spectroscopy Y1 - 2014 U6 - http://dx.doi.org/10.1016/j.proeng.2014.11.689 SN - 1877-7058 N1 - EUROSENSORS 2014 ; European Conference on Solid-State Transducers <28, 2014> VL - 87 SP - 1314 EP - 1317 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Murib, M. S. A1 - Yeap, W. S. A1 - Martens, D. A1 - Liu, X. A1 - Bienstman, P. A1 - Fahlman, M. A1 - Schöning, Michael Josef A1 - Michiels, L. A1 - Haenen, K. A1 - Serpengüzel, A. A1 - Wagner, Patrick T1 - Photonic studies on polymer-coated sapphire-spheres : a model system for biological ligands JF - Sensors and actuators A: Physical N2 - In this study we show an optical biosensor concept, based on elastic light scattering from sapphire microspheres. Transmitted and elastic scattering intensity of the microspheres (radius 500 μm, refractive index 1.77) on an optical fiber half coupler is analyzed at 1510 nm. The 0.43 nm angular mode spacing of the resonances is comparable to the angular mode spacing value estimated using the optical size of the microsphere. The spectral linewidths of the resonances are in the order of 0.01 nm, which corresponds to quality factors of approximately 105. A polydopamine layer is used as a functionalizing agent on sapphire microspherical resonators in view of biosensor implementation. The varying layer thickness on the microsphere is determined as a function of the resonance wavelength shift. It is shown that polymer functionalization has a minor effect on the quality factor. This is a promising step toward the development of an optical biosensor. Y1 - 2015 U6 - http://dx.doi.org/10.1016/j.sna.2014.11.024 SN - 1873-3069 (E-Journal); 0924-4247 (Print) VL - 222 SP - 212 EP - 219 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Schütz, S. A1 - Weißbecker, B. A1 - Hummel, Hans E. A1 - Schöning, Michael Josef A1 - Riemer, A. A1 - Kordos, P. A1 - Lüth, H. T1 - Field effect transistor-insect antenna junction JF - Naturwissenschaften Y1 - 1997 SN - 1432-1904 VL - 84 SP - 86 EP - 88 ER - TY - JOUR A1 - Thust, Marion A1 - Schöning, Michael Josef A1 - Frohnhoff, S. A1 - Arens-Fischer, R. A1 - Kordos, P. A1 - Lüth, H. T1 - Porous silicon as a substrate material for potentiometric biosensors JF - Measurement Science and Technology Y1 - 1996 U6 - http://dx.doi.org/10.1088/0957-0233/7/1/003 VL - 7 IS - 1 SP - 26 EP - 29 ER - TY - JOUR A1 - Schöning, Michael Josef A1 - Bäcker, Matthias T1 - Chip-basierte Sensoren für die Biotechnik Y1 - 2012 SN - 1611-0854 N1 - 4 Seiten VL - 13 IS - 2 PB - BIOCOM CY - Berlin ER - TY - JOUR A1 - Wagner, Torsten A1 - Miyamoto, K. A1 - Werner, Frederik A1 - Schöning, Michael Josef A1 - Yoshinobu, T. T1 - Utilising Digital Micro-Mirror Device (DMD) as Scanning Light Source for Light-Addressable Potentiometric Sensors (LAPS) Y1 - 2011 U6 - http://dx.doi.org/10.1166/sl.2011.1620 VL - 9 IS - 2 SP - 812 EP - 815 PB - American Scientific Publishers CY - Stevenson Ranch, Calif. ER - TY - JOUR A1 - Schöning, Michael Josef A1 - Poghossian, Arshak T1 - BioFEDs (field-effect devices) : State-of-the-art and new directions JF - Electroanalysis Y1 - 2006 U6 - http://dx.doi.org/10.1002/elan.200603609 SN - 1521-4109 VL - 18 IS - 19-20 SP - 1893 EP - 1900 ER - TY - JOUR A1 - Spelthahn, Heiko A1 - Schubert, Jürgen A1 - Schöning, Michael Josef T1 - Dünnschichtsensoren für die Schwermetallanalytik : Mikroelektroden auf Chalkogenidglasbasis JF - GIT Labor-Fachzeitschrift N2 - Die Detektion von Schadstoffen repräsentiert in der Umweltanalytik eine wichtige Aufgabenstellung. Gerade die Abwasser- bzw. Brauchwasseranalytik sowie die Prozesskontrolle haben einen hohen Stellenwert. Siliziumbasierte Dünnschichtsensoren bieten eine kostengünstige Möglichkeit, „online“-Messungen bzw. Vor-Ort-Messungen zeitnah durchzuführen. In dieser Arbeit wird ein potentiometrisches Sensorarray auf der Basis von Chalkogenidgläsern zur Detektion von Schwermetallen in wässrigen Medien vorgestellt. Y1 - 2012 IS - 4 SP - 285 EP - 287 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Wu, Chunsheng A1 - Bronder, Thomas A1 - Poghossian, Arshak A1 - Werner, Frederik A1 - Schöning, Michael Josef T1 - Label-free detection of DNA using light-addressable potentiometric sensor modified with a positively charged polyelectrolyte layer JF - Nanoscale N2 - A multi-spot (16 spots) light-addressable potentiometric sensor (MLAPS) consisting of an Al–p-Si–SiO2 structure modified with a weak polyelectrolyte layer of PAH (poly(allylamine hydrochloride)) was applied for the label-free electrical detection of DNA (deoxyribonucleic acid) immobilization and hybridization by the intrinsic molecular charge for the first time. To achieve a preferentially flat orientation of DNA strands and thus, to reduce the distance between the DNA charge and MLAPS surface, the negatively charged probe single-stranded DNAs (ssDNA) were electrostatically adsorbed onto the positively charged PAH layer using a simple layer-by-layer (LbL) technique. In this way, more DNA charge can be positioned within the Debye length, yielding a higher sensor signal. The surface potential changes in each spot induced due to the surface modification steps (PAH adsorption, probe ssDNA immobilization, hybridization with complementary target DNA (cDNA), non-specific adsorption of mismatched ssDNA) were determined from the shifts of photocurrent–voltage curves along the voltage axis. A high sensor signal of 83 mV was registered after immobilization of probe ssDNA onto the PAH layer. The hybridization signal increases from 5 mV to 32 mV with increasing the concentration of cDNA from 0.1 nM to 5 μM. In contrast, a small signal of 5 mV was recorded in the case of non-specific adsorption of fully mismatched ssDNA (5 μM). The obtained results demonstrate the potential of the MLAPS in combination with the simple and rapid LbL immobilization technique as a promising platform for the future development of multi-spot light-addressable label-free DNA chips with direct electrical readout. Y1 - 2015 U6 - http://dx.doi.org/10.1039/C4NR07225A VL - 14 IS - 7 SP - 6143 EP - 6150 PB - Royal Society of Chemistry (RSC) CY - Cambridge ER - TY - JOUR A1 - Beging, Stefan A1 - Leinhos, Marcel A1 - Jablonski, Melanie A1 - Poghossian, Arshak A1 - Schöning, Michael Josef T1 - Studying the spatially resolved immobilisation of enzymes on a capacitive field-effect structure by means of nano-spotting JF - Physica status solidi (a) Y1 - 2015 U6 - http://dx.doi.org/10.1002/pssa.201431891 SN - 1862-6319 VL - 212 IS - 6 SP - 1353 EP - 1358 PB - Wiley CY - Weinheim ER - TY - JOUR A1 - Poghossian, Arshak A1 - Katz, Evgeny A1 - Schöning, Michael Josef T1 - Enzyme logic AND-Reset and OR-Reset gates based on a field-effect electronic transducer modified with multi-enzyme membrane JF - Chemical Communications N2 - Capacitive field-effect sensors modified with a multi-enzyme membrane have been applied for an electronic transduction of biochemical signals processed by enzyme-based AND-Reset and OR-Reset logic gates. The local pH change at the sensor surface induced by the enzymatic reaction was used for the activation of the Reset function for the first time. Y1 - 2015 U6 - http://dx.doi.org/10.1039/C5CC01362C VL - 51 SP - 6564 EP - 6567 PB - Royal Society of Chemistry (RSC) CY - Cambridge ER - TY - JOUR A1 - Oberländer, Jan A1 - Bromm, Alexander A1 - Wendeler, Luisa A1 - Iken, Heiko A1 - Palomar Duran, Marlena A1 - Greeff, Anton A1 - Kirchner, Patrick A1 - Keusgen, Michael A1 - Schöning, Michael Josef T1 - Towards a biosensor to monitor the sterilisation efficiency of aseptic filling machines JF - Physica status solidi (a) N2 - Sterilisation processes are compulsory in medicine, pharmacy, and food industries to prevent infections of consumers and microbiological contaminations of products. Monitoring the sterilisation by conventional microbiological methods is time- and lab-consuming. To overcome this problem, in this work a novel biosensor has been proposed. The sensor enables a fast method to evaluate sterilisation processes. By means of thin-film technology the sensor's transducer structures in form of IDEs (interdigitated electrodes) have been fabricated on a silicon substrate. Physical characterisation of the developed sensor was done by AFM, SEM, and profilometry. Impedance analyses were conducted for the electrical characterisation. As microbiological layer spores of B. atrophaeus have been immobilised on the sensing structure; spores of this type are a well-known sterilisation test organism. Impedance measurements at a fixed frequency over time were performed to monitor the immobilisation process. A sterilisation process according to aseptic filling machines was applied to demonstrate the sensor functionality. After both, immobilisation and sterilisation, a change in impedance could successfully be detected. Y1 - 2015 U6 - http://dx.doi.org/10.1002/pssa.201431900 SN - 1862-6319 VL - 212 IS - 6 SP - 1299 EP - 1305 PB - Wiley CY - Weinheim ER - TY - JOUR A1 - Huck, Christina A1 - Poghossian, Arshak A1 - Bäcker, Matthias A1 - Reisert, Steffen A1 - Kramer, Friederike A1 - Begoyan, Vardges K. A1 - Buniatyan, Vahe V. A1 - Schöning, Michael Josef T1 - Multi-parameter sensing using high-k oxide of barium strontium titanate JF - Physica status solidi (a) N2 - High-k perovskite oxide of barium strontium titanate (BST) represents a very attractive multi-functional transducer material for the development of (bio-)chemical sensors. In this work, a Si-based sensor chip containing Pt interdigitated electrodes covered with a thin BST layer (485 nm) has been developed for multi-parameter chemical sensing. The chip has been applied for the contactless measurement of the electrolyte conductivity, the detection of adsorbed charged macromolecules (positively charged polyelectrolytes of polyethylenimine) and the concentration of hydrogen peroxide (H2O2) vapor. The experimental results of functional testing of individual sensors are presented. The mechanism of the BST sensitivity to charged polyelectrolytes and H2O2 vapor has been proposed and discussed. Y1 - 2015 U6 - http://dx.doi.org/10.1002/pssa.201431911 SN - 1862-6319 VL - 212 IS - 6 SP - 1259 PB - Wiley CY - Weinheim ER - TY - JOUR A1 - Jildeh, Zaid B. A1 - Wagner, Torsten A1 - Schöning, Michael Josef A1 - Pieper, Martin T1 - Simulating the electromagnetic‐thermal treatment of thin aluminium layers for adhesion improvement JF - Physica status solidi (a) N2 - A composite layer material used in packaging industry is made from joining layers of different materials using an adhesive. An important processing step in the production of aluminium-containing composites is the surface treatment and consequent coating of adhesive material on the aluminium surface. To increase adhesion strength between aluminium layer and the adhesive material, the foil is heat treated. For efficient heating, induction heating was considered as state-of-the-art treatment process. Due to the complexity of the heating process and the unpredictable nature of the heating source, the control of the process is not yet optimised. In this work, a finite element analysis of the process was established and various process parameters were studied. The process was simplified and modelled in 3D. The numerical model contains an air domain, an aluminium layer and a copper coil fitted with a magnetic field concentrating material. The effect of changing the speed of the aluminium foil (or rolling speed) was studied with the change of the coil current. Statistical analysis was used for generating a general control equation of coil current with changing rolling speed. Y1 - 2015 U6 - http://dx.doi.org/10.1002/pssa.201431893 SN - 1862-6319 VL - Vol. 212 IS - 6 SP - 1234 EP - 1241 PB - Wiley CY - Weinheim ER - TY - JOUR A1 - Pilas, Johanna A1 - Iken, Heiko A1 - Selmer, Thorsten A1 - Keusgen, Michael A1 - Schöning, Michael Josef T1 - Development of a multi‐parameter sensor chip for the simultaneous detection of organic compounds in biogas processes JF - Physica status solidi (a) N2 - An enzyme-based multi-parameter biosensor is developed for monitoring the concentration of formate, d-lactate, and l-lactate in biological samples. The sensor is based on the specific dehydrogenation by an oxidized β-nicotinamide adenine dinucleotide (NAD+)-dependent dehydrogenase (formate dehydrogenase, d-lactic dehydrogenase, and l-lactic dehydrogenase, respectively) in combination with a diaphorase from Clostridium kluyveri (EC 1.8.1.4). The enzymes are immobilized on a platinum working electrode by cross-linking with glutaraldehyde (GA). The principle of the determination scheme in case of l-lactate is as follows: l-lactic dehydrogenase (l-LDH) converts l-lactate into pyruvate by reaction with NAD+. In the presence of hexacyanoferrate(III), the resulting reduced β-nicotinamide adenine dinucleotide (NADH) is then regenerated enzymatically by diaphorase. The electrochemical detection is based on the current generated by oxidation of hexacyanoferrate(II) at an applied potential of +0.3 V vs. an Ag/AgCl reference electrode. The biosensor will be electrochemically characterized in terms of linear working range and sensitivity. Additionally, the successful practical application of the sensor is demonstrated in an extract from maize silage. Y1 - 2015 U6 - http://dx.doi.org/10.1002/pssa.201431894 SN - 1862-6319 VL - 212 IS - 6 SP - 1306 EP - 1312 PB - Wiley CY - Weinheim ER - TY - JOUR A1 - Breuer, Lars A1 - Raue, Markus A1 - Kirschbaum, M. A1 - Mang, Thomas A1 - Schöning, Michael Josef A1 - Thoelen, R. A1 - Wagner, Torsten T1 - Light-controllable polymeric material based on temperature-sensitive hydrogels with incorporated graphene oxide JF - Physica status solidi (a) N2 - Poly(N-isopropylacrylamide) (PNIPAAm) hydrogel films with incorporated graphene oxide (GO) were developed and tested as light-stimulated actuators. GO dispersions were synthesized via Hummers method and characterized toward their optical properties and photothermal energy conversion. The hydrogels were prepared by means of photopolymerization. In addition, the influence of GO within the hydrogel network on the lower critical solution temperature (LCST) was investigated by differential scanning calorimetry (DSC). The optical absorbance and the response to illumination were determined as a function of GO concentration for thin hydrogel films. A proof of principle for the stimulation with light was performed. Y1 - 2015 U6 - http://dx.doi.org/10.1002/pssa.201431944 SN - 1862-6319 VL - 212 IS - 6 SP - 1368 EP - 1374 PB - Wiley CY - Weinheim ER - TY - JOUR A1 - Dantism, S. A1 - Takenaga, S. A1 - Wagner, P. A1 - Wagner, Torsten A1 - Schöning, Michael Josef T1 - Light-addressable Potentiometric Sensor (LAPS) Combined with Multi-chamber Structures to Investigate the Metabolic Activity of Cells JF - Procedia Engineering N2 - LAPS are field-effect-based potentiometric sensors which are able to monitor analyte concentrations in a spatially resolved manner. Hence, a LAPS sensor system is a powerful device to record chemical imaging of the concentration of chemical species in an aqueous solution, chemical reactions, or the growth of cell colonies on the sensor surface, to record chemical images. In this work, multi-chamber 3D-printed structures made out of polymer (PP-ABS) were combined with LAPS chips to analyse differentially and simultaneously the metabolic activity of Escherichia coli K12 and Chinese hamster ovary (CHO) cells, and the responds of those cells to the addition of glucose solution. Y1 - 2015 U6 - http://dx.doi.org/10.1016/j.proeng.2015.08.647 SN - 1877-7058 N1 - Part of special issue "Eurosensors 2015" VL - 120 SP - 384 EP - 387 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Molinnus, Denise A1 - Bäcker, Matthias A1 - Siegert, Petra A1 - Willenberg, H. A1 - Poghossian, Arshak A1 - Keusgen, M. A1 - Schöning, Michael Josef T1 - Detection of Adrenaline Based on Substrate Recycling Amplification JF - Procedia Engineering N2 - An amperometric enzyme biosensor has been applied for the detection of adrenaline. The adrenaline biosensor has been prepared by modification of an oxygen electrode with the enzyme laccase that operates at a broad pH range between pH 3.5 to pH 8. The enzyme molecules were immobilized via cross-linking with glutaraldehyde. The sensitivity of the developed adrenaline biosensor in different pH buffer solutions has been studied. Y1 - 2015 U6 - http://dx.doi.org/10.1016/j.proeng.2015.08.708 SN - 1877-7058 N1 - Eurosensors 2015 VL - 120 SP - 540 EP - 543 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Schusser, Sebastian A1 - Krischer, M. A1 - Molin, D. G. M. A1 - Akker, N. M. S. van den A1 - Bäcker, Matthias A1 - Poghossian, Arshak A1 - Schöning, Michael Josef T1 - Sensor System for in-situ and Real-time Monitoring of Polymer (bio) degradation JF - Procedia Engineering N2 - A sensor system for investigating (bio)degradationprocesses of polymers is presented. The system utilizes semiconductor field-effect sensors and is capable of monitoring the degradation process in-situ and in real-time. The degradation of the polymer poly(d,l-lactic acid) is exemplarily monitored in solutions with different pH value, pH-buffer solution containing the model enzyme lipase from Rhizomucormiehei and cell-culture medium containing supernatants from stimulated and non-stimulated THP-1-derived macrophages mimicking activation of the immune system. Y1 - 2015 U6 - http://dx.doi.org/10.1016/j.proeng.2015.08.815 SN - 1877-7058 N1 - Eurosensors 2015 VL - 120 SP - 948 EP - 951 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Pilas, Johanna A1 - Mariano, K. A1 - Keusgen, M. A1 - Selmer, Thorsten A1 - Schöning, Michael Josef T1 - Optimization of an Enzyme-based Multi-parameter Biosensor for Monitoring Biogas Processes JF - Procedia Engineering Y1 - 2015 U6 - http://dx.doi.org/10.1016/j.proeng.2015.08.702 SN - 1877-7058 N1 - Part of special issue "Eurosensors 2015" VL - 120 SP - 532 EP - 535 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Miyamoto, Ko-ichiro A1 - Bing, Yu A1 - Wagner, Torsten A1 - Yoshinobu, Tatsuo A1 - Schöning, Michael Josef T1 - Visualization of Defects on a Cultured Cell Layer by Utilizing Chemical Imaging Sensor JF - Procedia Engineering N2 - The chemical imaging sensor is a field-effect sensor which is able to visualize both the distribution of ions (in LAPS mode) and the distribution of impedance (in SPIM mode) inthe sample. In this study, a novel wound-healing assay is proposed, in which the chemical imaging sensor operated in SPIM mode is applied to monitor the defect of a cell layer brought into proximity of the sensing surface.A reduced impedance inside the defect, which was artificially formed ina cell layer, was successfully visualized in a photocurrent image. Y1 - 2015 U6 - http://dx.doi.org/10.1016/j.proeng.2015.08.806 SN - 1877-7058 N1 - Part of special issue "Eurosensors 2015" VL - 120 SP - 936 EP - 939 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Bronder, Thomas A1 - Poghossian, Arshak A1 - Scheja, S. A1 - Wu, Chunsheng A1 - Keusgen, M. A1 - Schöning, Michael Josef T1 - Electrostatic Detection of Unlabelled Single- and Double-stranded DNA Using Capacitive Field-effect Devices Functionalized with a Positively Charged Polyelectrolyte Layer JF - Procedia Engineering N2 - Capacitive field-effect electrolyte-insulator-semiconductor sensors consisting of an Al-p-Si-SiO2 structure have been used for the electrical detection of unlabelled single- and double-stranded DNA (dsDNA) molecules by their intrinsic charge. A simple functionalization protocol based on the layer-by-layer (LbL) technique was used to prepare a weak polyelectrolyte/probe-DNA bilayer, followed by the hybridization with complementary target DNA molecules. Due to the flat orientation of the LbL-adsorbed DNA molecules, a high sensor signal has been achieved. In addition, direct label-free detection of in-solution hybridized dsDNA molecules has been studied. Y1 - 2015 U6 - http://dx.doi.org/10.1016/j.proeng.2015.08.710 SN - 1877-7058 N1 - Eurosensors 2015 VL - 120 SP - 544 EP - 547 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Yoshinobu, Tatsuo A1 - Moritz, Werner A1 - Finger, Friedhelm A1 - Schöning, Michael Josef ED - Comini, Elisabetta T1 - Application of thin-film amorphous silicon to chemical imaging JF - Nanostructured materials and hybrid composites for gas sensors and biomedical applications : symposium held April 18-20, 2006, San Francisco , California, U.S.A. Y1 - 2006 SN - 9781558998711 N1 - Materials Research Society symposia proceedings; v. 915 IS - Paper 0910-A-20-01 SP - 1 EP - 10 ER - TY - JOUR A1 - Schöning, Michael Josef A1 - Abouzar, Maryam H. A1 - Ingebrandt, Sven A1 - Platen, Johannes A1 - Offenhäusser, Andreas A1 - Poghossian, Arshak ED - Comini, Elisabetta T1 - Towards label-free detection of charged macromolecules using field-effect-based structures : Scaling down from capacitive EIS sensor over ISFET to nano-scale devices JF - Nanostructured materials and hybrid composites for gas sensors and biomedical applications : symposium held April 18-20, 2006, San Francisco , California, U.S.A. Y1 - 2006 SN - 9781558998711 IS - paper 0915-R05-04 SP - 89 EP - 94 ER - TY - JOUR A1 - Takenaga, Shoko A1 - Schneider, Benno A1 - Erbay, E. A1 - Biselli, Manfred A1 - Schnitzler, Thomas A1 - Schöning, Michael Josef A1 - Wagner, Torsten T1 - Fabrication of biocompatible lab-on-chip devices for biomedical applications by means of a 3D-printing process JF - Physica status solidi (a) N2 - A new microfluidic assembly method for semiconductor-based biosensors using 3D-printing technologies was proposed for a rapid and cost-efficient design of new sensor systems. The microfluidic unit is designed and printed by a 3D-printer in just a few hours and assembled on a light-addressable potentiometric sensor (LAPS) chip using a photo resin. The cell growth curves obtained from culturing cells within microfluidics-based LAPS systems were compared with cell growth curves in cell culture flasks to examine biocompatibility of the 3D-printed chips. Furthermore, an optimal cell culturing within microfluidics-based LAPS chips was achieved by adjusting the fetal calf serum concentrations of the cell culture medium, an important factor for the cell proliferation. Y1 - 2015 U6 - http://dx.doi.org/10.1002/pssa.201532053 SN - 1862-6319 VL - 212 IS - 6 SP - 1347 EP - 1352 PB - Wiley CY - Weinheim ER - TY - JOUR A1 - Molinnus, Denise A1 - Bäcker, Matthias A1 - Iken, Heiko A1 - Poghossian, Arshak A1 - Keusgen, Michael A1 - Schöning, Michael Josef T1 - Concept for a biomolecular logic chip with an integrated sensor and actuator function JF - Physica status solidi (a) N2 - A concept for a new generation of an integrated multi-functional biosensor/actuator system is developed, which is based on biomolecular logic principles. Such a system is expected to be able to detect multiple biochemical input signals simultaneously and in real-time and convert them into electrical output signals with logical operations such as OR, AND, etc. The system can be designed as a closed-loop drug release device triggered by an enzyme logic gate, while the release of the drug induced by the actuator at the required dosage and timing will be controlled by an additional drug sensor. Thus, the system could help to make an accurate and specific diagnosis. The presented concept is exemplarily demonstrated by using an enzyme logic gate based on a glucose/glucose oxidase system, a temperature-responsive hydrogel mimicking the actuator function and an insulin (drug) sensor. In this work, the results of functional testing of individual amperometric glucose and insulin sensors as well as an impedimetric sensor for the detection of the hydrogel swelling/shrinking are presented. Y1 - 2015 U6 - http://dx.doi.org/10.1002/pssa.201431913 SN - 1862-6319 VL - 212 IS - 6 SP - 1382 EP - 1388 PB - Wiley CY - Weinheim ER - TY - JOUR A1 - Warmer, Johannes A1 - Wagner, Patrick A1 - Schöning, Michael Josef A1 - Kaul, Peter T1 - Detection of triacetone triperoxide using temperature cycled metal-oxide semiconductor gas sensors JF - Physica status solidi (a) Y1 - 2015 U6 - http://dx.doi.org/10.1002/pssa.201431882 SN - 1862-6319 VL - 212 IS - 6 SP - 1289 EP - 1298 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Delle, Lotta E. A1 - Huck, Christina A1 - Bäcker, Matthias A1 - Müller, Frank A1 - Grandthyll, Samuel A1 - Jacobs, Karin A1 - Lilischkis, Rainer A1 - Vu, Xuan T. A1 - Schöning, Michael Josef A1 - Wagner, Patrick A1 - Thoelen, Roland A1 - Weil, Maryam A1 - Ingebrandt, Sven T1 - Impedimetric immunosensor for the detection of histamine based on reduced graphene oxide JF - Physica status solidi (a) Y1 - 2015 U6 - http://dx.doi.org/10.1002/pssa.201431863 SN - 1862-6319 VL - 212 IS - 6 SP - 1327 EP - 1334 PB - Wiley CY - Weinheim ER - TY - JOUR A1 - Bronder, Thomas A1 - Poghossian, Arshak A1 - Scheja, Sabrina A1 - Wu, Chunsheng A1 - Keusgen, Michael A1 - Mewes, Dieter A1 - Schöning, Michael Josef T1 - DNA Immobilization and Hybridization Detection by the Intrinsic Molecular Charge Using Capacitive Field-Effect Sensors Modified with a Charged Weak Polyelectrolyte Layer JF - Applied Materials & Interfaces N2 - Miniaturized setup, compatibility with advanced micro- and nanotechnologies, and ability to detect biomolecules by their intrinsic molecular charge favor the semiconductor field-effect platform as one of the most attractive approaches for the development of label-free DNA chips. In this work, a capacitive field-effect EIS (electrolyte–insulator–semiconductor) sensor covered with a layer-by-layer prepared, positively charged weak polyelectrolyte layer of PAH (poly(allylamine hydrochloride)) was used for the label-free electrical detection of DNA (deoxyribonucleic acid) immobilization and hybridization. The negatively charged probe single-stranded DNA (ssDNA) molecules were electrostatically adsorbed onto the positively charged PAH layer, resulting in a preferentially flat orientation of the ssDNA molecules within the Debye length, thus yielding a reduced charge-screening effect and a higher sensor signal. Each sensor-surface modification step (PAH adsorption, probe ssDNA immobilization, hybridization with complementary target DNA (cDNA), reducing an unspecific adsorption by a blocking agent, incubation with noncomplementary DNA (ncDNA) solution) was monitored by means of capacitance–voltage and constant-capacitance measurements. In addition, the surface morphology of the PAH layer was studied by atomic force microscopy and contact-angle measurements. High hybridization signals of 34 and 43 mV were recorded in low-ionic strength solutions of 10 and 1 mM, respectively. In contrast, a small signal of 4 mV was recorded in the case of unspecific adsorption of fully mismatched ncDNA. The density of probe ssDNA and dsDNA molecules as well as the hybridization efficiency was estimated using the experimentally measured DNA immobilization and hybridization signals and a simplified double-layer capacitor model. The results of field-effect experiments were supported by fluorescence measurements, verifying the DNA-immobilization and hybridization event. Y1 - 2015 U6 - http://dx.doi.org/10.1021/acsami.5b05146 VL - 36 IS - 7 SP - 20068 EP - 20075 PB - American Chemical Society CY - Washington, DC ER - TY - JOUR A1 - Oberländer, Jan A1 - Jildeh, Zaid B. A1 - Kirchner, Patrick A1 - Wendeler, Luisa A1 - Bromm, Alexander A1 - Iken, Heiko A1 - Wagner, Patrick A1 - Keusgen, Michael A1 - Schöning, Michael Josef T1 - Study of Interdigitated Electrode Arrays Using Experiments and Finite Element Models for the Evaluation of Sterilization Processes JF - Sensors N2 - In this work, a sensor to evaluate sterilization processes with hydrogen peroxide vapor has been characterized. Experimental, analytical and numerical methods were applied to evaluate and study the sensor behavior. The sensor set-up is based on planar interdigitated electrodes. The interdigitated electrode structure consists of 614 electrode fingers spanning over a total sensing area of 20 mm2. Sensor measurements were conducted with and without microbiological spores as well as after an industrial sterilization protocol. The measurements were verified using an analytical expression based on a first-order elliptical integral. A model based on the finite element method with periodic boundary conditions in two dimensions was developed and utilized to validate the experimental findings. Y1 - 2015 U6 - http://dx.doi.org/10.3390/s151026115 SN - 1424-8220 N1 - This article belongs to the Special Issue "Gas Sensors—Designs and Applications" VL - 15 IS - 10 SP - 26115 EP - 26127 PB - MDPI CY - Basel ER - TY - JOUR A1 - Schusser, Sebastian A1 - Krischer, Maximillian A1 - Bäcker, Matthias A1 - Poghossian, Arshak A1 - Wagner, Patrick A1 - Schöning, Michael Josef T1 - Monitoring of the Enzymatically Catalyzed Degradation of Biodegradable Polymers by Means of Capacitive Field-Effect Sensors JF - Analytical Chemistry N2 - Designing novel or optimizing existing biodegradable polymers for biomedical applications requires numerous tests on the effect of substances on the degradation process. In the present work, polymer-modified electrolyte–insulator–semiconductor (PMEIS) sensors have been applied for monitoring an enzymatically catalyzed degradation of polymers for the first time. The thin films of biodegradable polymer poly(d,l-lactic acid) and enzyme lipase were used as a model system. During degradation, the sensors were read-out by means of impedance spectroscopy. In order to interpret the data obtained from impedance measurements, an electrical equivalent circuit model was developed. In addition, morphological investigations of the polymer surface have been performed by means of in situ atomic force microscopy. The sensor signal change, which reflects the progress of degradation, indicates an accelerated degradation in the presence of the enzyme compared to hydrolysis in neutral pH buffer media. The degradation rate increases with increasing enzyme concentration. The obtained results demonstrate the potential of PMEIS sensors as a very promising tool for in situ and real-time monitoring of degradation of polymers. Y1 - 2015 U6 - http://dx.doi.org/10.1021/acs.analchem.5b00617 SN - 1520-6882 VL - 87 IS - 13 SP - 6607 EP - 6613 PB - ACS Publications CY - Washington, DC ER - TY - JOUR A1 - Miyamato, Ko-ichiro A1 - Sakakita, Sakura A1 - Wagner, Torsten A1 - Schöning, Michael Josef A1 - Yoshinobu, Tatsuo T1 - Application of chemical imaging sensor to in-situ pH imaging in the vicinity of a corroding metal surface JF - Electrochimica Acta N2 - The chemical imaging sensor was applied to in-situ pH imaging of the solution in the vicinity of a corroding surface of stainless steel under potentiostatic polarization. A test piece of polished stainless steel was placed on the sensing surface leaving a narrow gap filled with artificial seawater and the stainless steel was corroded under polarization. The pH images obtained during polarization showed correspondence between the region of lower pH and the site of corrosion. It was also found that the pH value in the gap became as low as 2 by polarization, which triggered corrosion. Y1 - 2015 U6 - http://dx.doi.org/10.1016/j.electacta.2015.07.184 SN - 0013-4686 VL - 183 SP - 137 EP - 142 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Oberländer, Jan A1 - Kirchner, Patrick A1 - Keusgen, Michael A1 - Schöning, Michael Josef T1 - Strategies in developing thin-film sensors for monitoring aseptic food processes : Theoretical considerations and investigations of passivation materials JF - Electrochimica Acta N2 - The sterilization of packages in aseptic food processes is highly significant to maintain a consumer-safe product with extended shelf-life. Today, the sterilization of food packages is predominantly accomplished by gaseous hydrogen peroxide (H2O2) in combination with heat. In order to monitor this sterilization process, calorimetric gas sensors as differential set-up of two platinum temperature sensors representing a catalytically active (additionally deposition of MnO2) and a passive segment have been recently developed. The temperature rise of the exothermic decomposition serves as an indicator of the present H2O2 concentration. In the present work, a theoretical approach considering the sensor’s thermochemistry and physical transport phenomena was formulated to evaluate the temperature rise based on the energy content of gaseous H2O2. In a further part of this work, three polymers have been analyzed with respect to their application as passivation materials. The examined polymers are photoresist SU-8, perfluoroalkoxy (PFA) and fluorinated ethylene propylene (FEP). Thermal analyses by means of differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) have been conducted to determine the operation limits of the polymers. The overall chemical resistance and stability of the polymers against the harsh environmental conditions during the sterilization process have been examined by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR). Y1 - 2015 U6 - http://dx.doi.org/10.1016/j.electacta.2015.06.126 SN - 0013-4686 VL - 183 SP - 130 EP - 136 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Murib, M. S. A1 - Yeap, W. S. A1 - Eurlings, Y. A1 - Grinsven, B. van A1 - Boyen, H.-G. A1 - Conings, B. A1 - Michiels, L. A1 - Ameloot, M. A1 - Carleer, R. A1 - Warmer, J. A1 - Kaul, P. A1 - Haenen, K. A1 - Schöning, Michael Josef A1 - Ceuninck, W. de A1 - Wagner, P. T1 - Heat-transfer based characterization of DNA on synthetic sapphire chips JF - Sensors and Actuators B: Chemical N2 - In this study, we show that synthetic sapphire (Al₂O₃), an established implant material, can also serve as a platform material for biosensors comparable to nanocrystalline diamond. Sapphire chips, beads, and powder were first modified with (3-aminopropyl) triethoxysilane (APTES), followed by succinic anhydride (SA), and finally single-stranded probe DNA was EDC coupled to the functionalized layer. The presence of the APTES-SA layer on sapphire powders was confirmed by thermogravimetric analyis and Fourier-transform infrared spectroscopy. Using planar sapphire chips as substrates and X-ray photoelectron spectroscopy (XPS) as surface-sensitive tool, the sequence of individual layers was analyzed with respect to their chemical state, enabling the quantification of areal densities of the involved molecular units. Fluorescence microscopy was used to demonstrate the hybridization of fluorescently tagged target DNA to the probe DNA, including denaturation- and re-hybridization experiments. Due to its high thermal conductivity, synthetic sapphire is especially suitable as a chip material for the heat-transfer method, which was employed to distinguish complementary- and non-complementary DNA duplexes containing single-nucleotide polymorphisms. These results indicate that it is possible to detect mutations electronically with a chemically resilient and electrically insulating chip material. Y1 - 2016 U6 - http://dx.doi.org/10.1016/j.snb.2016.02.027 SN - 0925-4005 VL - 230 IS - 230 SP - 260 EP - 271 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Hamad, E. M. A1 - Bilatto, S. E. R. A1 - Adly, N. Y. A1 - Correa, D. S. A1 - Wolfrum, B. A1 - Schöning, Michael Josef A1 - Offenhäusser, A. A1 - Yakushenko, A. T1 - Inkjet printing of UV-curable adhesive and dielectric inks for microfluidic devices JF - Lab on a Chip N2 - Bonding of polymer-based microfluidics to polymer substrates still poses a challenge for Lab-On-a-Chip applications. Especially, when sensing elements are incorporated, patterned deposition of adhesives with curing at ambient conditions is required. Here, we demonstrate a fabrication method for fully printed microfluidic systems with sensing elements using inkjet and stereolithographic 3D-printing. Y1 - 2016 U6 - http://dx.doi.org/10.1039/C5LC01195G SN - 1473-0189 VL - 16 IS - 1 SP - 70 EP - 74 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Miyamoto, Ko-ichiro A1 - Yu, Bing A1 - Isoda, Hiroko A1 - Wagner, Torsten A1 - Schöning, Michael Josef A1 - Yoshinobu, Tatsuo T1 - Visualization of the recovery process of defects in a cultured cell layer by chemical imaging sensor JF - Sensors and Actuators B: Chemical N2 - The chemical imaging sensor is a field-effect sensor which is able to visualize both the distribution of ions (in LAPS mode) and the distribution of impedance (in SPIM mode) in the sample. In this study, a novel cell assay is proposed, in which the chemical imaging sensor operated in SPIM mode is applied to monitor the recovery of defects in a cell layer brought into proximity of the sensing surface. A reduced impedance at a defect formed artificially in a cell layer was successfully visualized in a photocurrent image. The cell layer was cultured over two weeks, during which the temporal change of the photocurrent distribution corresponding to the recovery of the defect was observed. Y1 - 2016 U6 - http://dx.doi.org/10.1016/j.snb.2016.04.018 SN - 0925-4005 VL - 236 SP - 965 EP - 969 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Dantism, Shahriar A1 - Takenaga, Shoko A1 - Wagner, Patrick A1 - Wagner, Torsten A1 - Schöning, Michael Josef T1 - Determination of the extracellular acidification of Escherichia coli K12 with a multi-​chamber-​based LAPS system JF - Physica status solidi (a) N2 - On-line monitoring of the metabolic activity of microorganisms involved in intermediate stages of biogas production plays an important role to avoid undesirable “down times” during the biogas production. In order to control this process, an on-chip differential measuring system based on the light-addressable potentiometric sensor (LAPS) principle combined with a 3D-printed multi-chamber structure has been realized. As a test microorganism, Escherichia coli K12 (E. coli K12) were used for cell-based measurements. Multi-chamber structures were developed to determine the metabolic activity of E. coli K12 in suspension for a different number of cells, responding to the addition of a constant or variable amount of glucose concentrations, enabling differential and simultaneous measurements. Y1 - 2016 U6 - http://dx.doi.org/10.1002/pssa.201533043 SN - 1862-6300 VL - 213 IS - 6 SP - 1479 EP - 1485 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Breuer, Lars A1 - Raue, Markus A1 - Strobel, M. A1 - Mang, Thomas A1 - Schöning, Michael Josef A1 - Thoelen, R. A1 - Wagner, Torsten T1 - Hydrogels with incorporated graphene oxide as light-addressable actuator materials for cell culture environments in lab-on-chip systems JF - Physica status solidi (a) N2 - Abstractauthoren Graphene oxide (GO) nanoparticles were incorporated in temperature-sensitive Poly(N-isopropylacrylamide) (PNIPAAm) hydrogels. The nanoparticles increase the light absorption and convert light energy into heat efficiently. Thus, the hydrogels with GO can be stimulated spatially resolved by illumination as it was demonstrated by IR thermography. The temporal progression of the temperature maximum was detected for different concentrations of GO within the polymer network. Furthermore, the compatibility of PNIPAAm hydrogels with GO and cell cultures was investigated. For this purpose, culture medium was incubated with hydrogels containing GO and the viability and morphology of chinese hamster ovary (CHO) cells was examined after several days of culturing in presence of this medium. Y1 - 2016 U6 - http://dx.doi.org/10.1002/pssa.201533056 SN - 1862-6300 VL - 213 IS - 6 SP - 1520 EP - 1525 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Arreola, Julio A1 - Mätzkow, Malte A1 - Durán, Marlena Palomar A1 - Greeff, Anton A1 - Keusgen, Michael A1 - Schöning, Michael Josef T1 - Optimization of the immobilization of bacterial spores on glass substrates with organosilanes JF - Physica status solidi (A) : Applications and materials science N2 - Spores can be immobilized on biosensors to function as sensitive recognition elements. However, the immobilization can affect the sensitivity and reproducibility of the sensor signal. In this work, three different immobilization strategies with organosilanes were optimized and characterized to immobilize Bacillus atrophaeus spores on glass substrates. Five different silanization parameters were investigated: nature of the solvent, concentration of the silane, silanization time, curing process, and silanization temperature. The resulting silane layers were resistant to a buffer solution (e.g., Ringer solution) with a polysorbate (e.g., Tween®80) and sonication. KW - silanization KW - organosilanes KW - immobilization KW - endospores KW - biosensors KW - Bacillus atrophaeus Y1 - 2016 U6 - http://dx.doi.org/10.1002/pssa.201532914 SN - 1862-6319 VL - 213 IS - 6 SP - 1463 EP - 1470 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Wu, Chunsheng A1 - Poghossian, Arshak A1 - Bronder, Thomas A1 - Schöning, Michael Josef T1 - Sensing of double-stranded DNA molecules by their intrinsic molecular charge using the light-addressable potentiometric sensor JF - Sensors and Actuators B: Chemical N2 - A multi-spot light-addressable potentiometric sensor (LAPS), which belongs to the family of semiconductor field-effect devices, was applied for label-free detection of double-stranded deoxyribonucleic acid (dsDNA) molecules by their intrinsic molecular charge. To reduce the distance between the DNA charge and sensor surface and thus, to enhance the electrostatic coupling between the dsDNA molecules and the LAPS, the negatively charged dsDNA molecules were electrostatically adsorbed onto the gate surface of the LAPS covered with a positively charged weak polyelectrolyte layer of PAH (poly(allylamine hydrochloride)). The surface potential changes in each spot of the LAPS, induced by the layer-by-layer adsorption of a PAH/dsDNA bilayer, were recorded by means of photocurrent-voltage and constant-photocurrent measurements. In addition, the surface morphology of the gate surface before and after consecutive electrostatic adsorption of PAH and dsDNA layers was studied by atomic force microscopy measurements. Moreover, fluorescence microscopy was used to verify the successful adsorption of dsDNA molecules onto the PAH-modified LAPS surface. A high sensor signal of 25 mV was registered after adsorption of 10 nM dsDNA molecules. The lower detection limit is down to 0.1 nM dsDNA. The obtained results demonstrate that the PAH-modified LAPS device provides a convenient and rapid platform for the direct label-free electrical detection of in-solution hybridized dsDNA molecules. KW - Layer-by-layer adsorption KW - Poly(allylamine hydrochloride) KW - Label-free detection KW - DNA biosensor KW - LAPS KW - Field effect Y1 - 2016 U6 - http://dx.doi.org/10.1016/j.snb.2016.02.004 SN - 0925-4005 IS - 229 SP - 506 EP - 512 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Bäcker, Matthias A1 - Koch, Claudia A1 - Eiben, Sabine A1 - Geiger, Fania A1 - Eber, Fabian A1 - Gliemann, Hartmut A1 - Poghossian, Arshak A1 - Wege, Christina A1 - Schöning, Michael Josef T1 - Tobacco mosaic virus as enzyme nanocarrier for electrochemical biosensors JF - Sensors and Actuators B: Chemical N2 - The conjunction of (bio-)chemical recognition elements with nanoscale biological building blocks such as virus particles is considered as a very promising strategy for the creation of biohybrids opening novel opportunities for label-free biosensing. This work presents a new approach for the development of biosensors using tobacco mosaic virus (TMV) nanotubes or coat proteins (CPs) as enzyme nanocarriers. Sensor chips combining an array of Pt electrodes loaded with glucose oxidase (GOD)-modified TMV nanotubes or CP aggregates were used for amperometric detection of glucose as a model system for the first time. The presence of TMV nanotubes or CPs on the sensor surface allows binding of a high amount of precisely positioned enzymes without substantial loss of their activity, and may also ensure accessibility of their active centers for analyte molecules. Specific and efficient immobilization of streptavidin-conjugated GOD ([SA]-GOD) complexes on biotinylated TMV nanotubes or CPs was achieved via bioaffinity binding. These layouts were tested in parallel with glucose sensors with adsorptively immobilized [SA]-GOD, as well as [SA]-GOD crosslinked with glutardialdehyde, and came out to exhibit superior sensor performance. The achieved results underline a great potential of an integration of virus/biomolecule hybrids with electronic transducers for future applications in biosensorics and biochips. Y1 - 2017 U6 - http://dx.doi.org/10.1016/j.snb.2016.07.096 SN - 0925-4005 VL - 238 SP - 716 EP - 722 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Wagner, Torsten A1 - Vornholt, Wolfgang A1 - Werner, Frederik A1 - Yoshinobu, Tatsuo A1 - Miyamoto, Ko-Ichiro A1 - Keusgen, Michael A1 - Schöning, Michael Josef T1 - Light-addressable potentiometric sensor (LAPS) combined with magnetic beads for pharmaceutical screening JF - Physics in medicine N2 - The light-addressable potentiometric sensor (LAPS) has the unique feature to address different regions of a sensor surface without the need of complex structures. Measurements at different locations on the sensor surface can be performed in a common analyte solution, which distinctly simplifies the fluidic set-up. However, the measurement in a single analyte chamber prevents the application of different drugs or different concentrations of a drug to each measurement spot at the same time as in the case of multi-reservoir-based set-ups. In this work, the authors designed a LAPS-based set-up for cell culture screening that utilises magnetic beads loaded with the endotoxin (lipopolysaccharides, LPS), to generate a spatially distributed gradient of analyte concentration. Different external magnetic fields can be adjusted to move the magnetic beads loaded with a specific drug within the measurement cell. By recording the metabolic activities of a cell layer cultured on top of the LAPS surface, this work shows the possibility to apply different concentrations of a sample along the LAPS measurement spots within a common analyte solution. Y1 - 2016 U6 - http://dx.doi.org/10.1016/j.phmed.2016.03.001 SN - 2352-4510 VL - 2016 IS - 1 SP - 2 EP - 7 ER - TY - JOUR A1 - Doll, Theodor A1 - Wagner, Torsten A1 - Wagner, Patrick A1 - Schöning, Michael Josef T1 - Engineering of functional interfaces / Theodor Doll ; Torsten Wagner ; Patrick Wagner ; Michael J. Schöning (eds.) JF - Physica status solidi (a) Y1 - 2016 U6 - http://dx.doi.org/10.1002/pssa.201670641 SN - 1862-6319 VL - 213 IS - 6 SP - 1393 EP - 1394 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Molinnus, Denise A1 - Sorich, Maren A1 - Bartz, Alexander A1 - Siegert, Petra A1 - Willenberg, Holger S. A1 - Lisdat, Fred A1 - Poghossian, Arshak A1 - Keusgen, Michael A1 - Schöning, Michael Josef T1 - Towards an adrenaline biosensor based on substrate recycling amplification in combination with an enzyme logic gate JF - Sensors and Actuators B: Chemical N2 - An amperometric biosensor using a substrate recycling principle was realized for the detection of low adrenaline concentrations (1 nM) by measurements in phosphate buffer and Ringer’s solution at pH 6.5 and pH 7.4, respectively. In proof-of-concept experiments, a Boolean logic-gate principle has been applied to develop a digital adrenaline biosensor based on an enzyme AND logic gate. The obtained results demonstrate that the developed digital biosensor is capable for a rapid qualitative determination of the presence/absence of adrenaline in a YES/NO statement. Such digital biosensor could be used in clinical diagnostics for the control of a correct insertion of a catheter in the adrenal veins during adrenal venous-sampling procedure. Y1 - 2016 U6 - http://dx.doi.org/10.1016/j.snb.2016.06.064 SN - 0925-4005 VL - 237 SP - 190 EP - 195 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Miyamoto, Ko-Ichiro A1 - Sato, Takuya A1 - Abe, Minami A1 - Wagner, Torsten A1 - Schöning, Michael Josef A1 - Yoshinobu, Tatsuo T1 - Light-addressable potentiometric sensor as a sensing element in plug-based microfluidic devices JF - Micromachines N2 - A plug-based microfluidic system based on the principle of the light-addressable potentiometric sensor (LAPS) is proposed. The LAPS is a semiconductor-based chemical sensor, which has a free addressability of the measurement point on the sensing surface. By combining a microfluidic device and LAPS, ion sensing can be performed anywhere inside the microfluidic channel. In this study, the sample solution to be measured was introduced into the channel in a form of a plug with a volume in the range of microliters. Taking advantage of the light-addressability, the position of the plug could be monitored and pneumatically controlled. With the developed system, the pH value of a plug with a volume down to 400 nL could be measured. As an example of plug-based operation, two plugs were merged in the channel, and the pH change was detected by differential measurement. KW - light-addressable potentiometric sensor KW - plug-based microfluidic device KW - chemical sensor Y1 - 2016 U6 - http://dx.doi.org/10.3390/mi7070111 SN - 2072-666X N1 - This article belongs to the Special Issue "Micro/Nano Devices for Chemical Analysis" VL - 7 IS - 7 SP - 111 PB - MDPI CY - Basel ER - TY - JOUR A1 - Poghossian, Arshak A1 - Werner, Frederik A1 - Buniatyan, V. V. A1 - Wagner, Torsten A1 - Miamoto, K. A1 - Yoshinobu, T. A1 - Schöning, Michael Josef T1 - Towards addressability of light-addressable potentiometric sensors: Shunting effect of non-illuminated region and cross-talk JF - Sensor and Actuators B: Chemical N2 - The LAPS (light-addressable potentiometric sensor) platform is one of the most attractive approaches for chemical and biological sensing with many applications ranging from pH and ion/analyte concentration measurements up to cell metabolism detection and chemical imaging. However, although it is generally accepted that LAPS measurements are spatially resolved, the light-addressability feature of LAPS devices has not been discussed in detail so far. In this work, an extended electrical equivalent-circuit model of the LAPS has been presented, which takes into account possible cross-talk effects due to the capacitive coupling of the non-illuminated region. A shunting effect of the non-illuminated area on the measured photocurrent and addressability of LAPS devices has been studied. It has been shown, that the measured photocurrent will be determined not only by the local interfacial potential in the illuminated region but also by possible interfacial potential changes in the non-illuminated region, yielding cross-talk effects. These findings were supported by the experimental investigations of a penicillin-sensitive multi-spot LAPS and a metal-insulator-semiconductor LAPS as model systems. Y1 - 2017 U6 - http://dx.doi.org/10.1016/j.snb.2017.01.047 SN - 0925-4005 IS - 244 SP - 1071 EP - 1079 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Katz, Evgeny A1 - Poghossian, Arshak A1 - Schöning, Michael Josef T1 - Enzyme-based logic gates and circuits - analytical applications and interfacing with electronics JF - Analytical and Bioanalytical Chemistry N2 - The paper is an overview of enzyme-based logic gates and their short circuits, with specific examples of Boolean AND and OR gates, and concatenated logic gates composed of multi-step enzyme-biocatalyzed reactions. Noise formation in the biocatalytic reactions and its decrease by adding a “filter” system, converting convex to sigmoid response function, are discussed. Despite the fact that the enzyme-based logic gates are primarily considered as components of future biomolecular computing systems, their biosensing applications are promising for immediate practical use. Analytical use of the enzyme logic systems in biomedical and forensic applications is discussed and exemplified with the logic analysis of biomarkers of various injuries, e.g., liver injury, and with analysis of biomarkers characteristic of different ethnicity found in blood samples on a crime scene. Interfacing of enzyme logic systems with modified electrodes and semiconductor devices is discussed, giving particular attention to the interfaces functionalized with signal-responsive materials. Future perspectives in the design of the biomolecular logic systems and their applications are discussed in the conclusion. Y1 - 2017 U6 - http://dx.doi.org/10.1007/s00216-016-0079-7 SN - 1618-2650 VL - 409 SP - 81 EP - 94 PB - Springer CY - Berlin ER - TY - JOUR A1 - Honarvarfard, Elham A1 - Gamella, Maria A1 - Channaveerappa, Devika A1 - Darie, Costel C. A1 - Poghossian, Arshak A1 - Schöning, Michael Josef A1 - Katz, Evgeny T1 - Electrochemically Stimulated Insulin Release from a Modified Graphene–functionalized Carbon Fiber Electrode JF - Electroanalysis N2 - A graphene-functionalized carbon fiber electrode was modified with adsorbed polyethylenimine to introduce amino functionalities and then with trigonelline and 4-carboxyphenylboronic acid covalently bound to the amino groups. The trigonelline species containing quarterized pyridine groups produced positive charge on the electrode surface regardless of the pH value, while the phenylboronic acid species were neutral below pH 8 and negatively charged above pH 9 (note that their pKa=8.4). The total charge on the monolayer-modified electrode was positive at the neutral pH and negative at pH > 9. Note that 4-carboxyphenylboronic acid was attached to the electrode surface in molar excess to trigonelline, thus allowing the negative charge to dominate on the electrode surface at basic pH. Negatively charged fluorescent dye-labeled insulin (insulin-FITC) was loaded on the modified electrode surface at pH 7.0 due to its electrostatic attraction to the positively charged interface. The local pH in close vicinity to the electrode surface was increased to ca. 9–10 due to consumption of H+ ions upon electrochemical reduction of oxygen proceeding at the potential of −1.0 V (vs. Ag/AgCl) applied on the modified electrode. The process resulted in recharging of the electrode surface to the negative value due to the formation of the negative charge on the phenylboronic acid groups, thus resulting in the electrostatic repulsion of insulin-FITC and stimulating its release from the electrode surface. The insulin release was characterized by fluorescence spectroscopy (using the FITC-labeled insulin), by electrochemical measurements on an iridium oxide, IrOx, electrode and by mass spectrometry. The graphene-functionalized carbon fiber electrode demonstrated significant advantages in the signal-stimulated insulin release comparing with the carbon fiber electrode without the graphene species. Y1 - 2017 U6 - http://dx.doi.org/10.1002/elan.201700095 SN - 1521-4109 VL - 29 IS - 6 SP - 1543 EP - 1553 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Gamella, Maria A1 - Zakharchenko, Andrey A1 - Guz, Nataliia A1 - Masi, Madeline A1 - Minko, Sergiy A1 - Kolpashchikov, Dmitry M. A1 - Iken, Heiko A1 - Poghossian, Arshak A1 - Schöning, Michael Josef A1 - Katz, Evgeny T1 - DNA computing system activated by electrochemically triggered DNA realease from a polymer-brush-modified electrode array JF - Electroanalysis N2 - An array of four independently wired indium tin oxide (ITO) electrodes was used for electrochemically stimulated DNA release and activation of DNA-based Identity, AND and XOR logic gates. Single-stranded DNA molecules were loaded on the mixed poly(N,N-dimethylaminoethyl methacrylate) (PDMAEMA)/poly(methacrylic acid) (PMAA) brush covalently attached to the ITO electrodes. The DNA deposition was performed at pH 5.0 when the polymer brush is positively charged due to protonation of tertiary amino groups in PDMAEMA, thus resulting in electrostatic attraction of the negatively charged DNA. By applying electrolysis at −1.0 V(vs. Ag/AgCl reference) electrochemical oxygen reduction resulted in the consumption of hydrogen ions and local pH increase near the electrode surface. The process resulted in recharging the polymer brush to the negative state due to dissociation of carboxylic groups of PMAA, thus repulsing the negatively charged DNA and releasing it from the electrode surface. The DNA release was performed in various combinations from different electrodes in the array assembly. The released DNA operated as input signals for activation of the Boolean logic gates. The developed system represents a step forward in DNA computing, combining for the first time DNA chemical processes with electronic input signals. Y1 - 2017 U6 - http://dx.doi.org/10.1002/elan.201600389 SN - 1521-4109 VL - 29 IS - 2 SP - 398 EP - 408 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Sousa, Marcos A. M. A1 - Siqueira, Jose R. Jr. A1 - Vercik, Andres A1 - Schöning, Michael Josef A1 - Oliveira, Osvaldo N. Jr. T1 - Determining the optimized layer-by-layer film architecture with dendrimer/carbon nanotubes for field-effect sensors JF - IEEE Sensors Journal N2 - The capacitive electrolyte–insulator–semiconductor (EIS) structure is a typical device based on a field-effect sensor platform. With a simple silicon-based structure, EIS have been useful for several sensing applications, especially with incorporation of nanostructured films to modulate the ionic transport and the flat-band potential. In this paper, we report on ion transport and changes in flat-band potential in EIS sensors made with layer-by-layer films containing poly(amidoamine) (PAMAM) dendrimer and single-walled carbon nanotubes (SWNTs) adsorbed on p-Si/SiO 2 /Ta 2 O 5 chips with an Al ohmic contact. The impedance spectra were fitted using an equivalent circuit model, from which we could determine parameters such as the double-layer capacitance. This capacitance decreased with the number of bilayers owing to space charge accumulated at the electrolyte–insulator interface, up to three PAMAM/SWNTs bilayers, after which it stabilized. The charge-transfer resistance was also minimum for three bilayers, thus indicating that this is the ideal architecture for an optimized EIS performance. The understanding of the influence of nanostructures and the fine control of operation parameters pave the way for optimizing the design and performance of new EIS sensors. Y1 - 2017 U6 - http://dx.doi.org/10.1109/JSEN.2017.2653238 SN - 1558-1748 VL - 17 IS - 6 SP - 1735 EP - 1740 PB - IEEE CY - New York ER - TY - JOUR A1 - Yoshinobu, Tatsuo A1 - Miyamoto, Ko-ichiro A1 - Werner, Frederik A1 - Poghossian, Arshak A1 - Wagner, Torsten A1 - Schöning, Michael Josef T1 - Light-addressable potentiometric sensors for quantitative spatial imaging of chemical species JF - Annual Review of Analytical Chemistry N2 - A light-addressable potentiometric sensor (LAPS) is a semiconductor-based chemical sensor, in which a measurement site on the sensing surface is defined by illumination. This light addressability can be applied to visualize the spatial distribution of pH or the concentration of a specific chemical species, with potential applications in the fields of chemistry, materials science, biology, and medicine. In this review, the features of this chemical imaging sensor technology are compared with those of other technologies. Instrumentation, principles of operation, and various measurement modes of chemical imaging sensor systems are described. The review discusses and summarizes state-of-the-art technologies, especially with regard to the spatial resolution and measurement speed; for example, a high spatial resolution in a submicron range and a readout speed in the range of several tens of thousands of pixels per second have been achieved with the LAPS. The possibility of combining this technology with microfluidic devices and other potential future developments are discussed. Y1 - 2017 U6 - http://dx.doi.org/10.1146/annurev-anchem-061516-045158 SN - 1936-1327 VL - 10 SP - 225 EP - 246 PB - Annual Reviews CY - Palo Alto, Calif. ER - TY - JOUR A1 - Arreola, Julio A1 - Oberländer, Jan A1 - Mätzkow, M. A1 - Keusgen, Michael A1 - Schöning, Michael Josef T1 - Surface functionalization for spore-based biosensors with organosilanes JF - Electrochimica Acta N2 - In the present work, surface functionalization of different sensor materials was studied. Organosilanes are well known to serve as coupling agent for biomolecules or cells on inorganic materials. 3-aminopropyltriethoxysilane (APTES) was used to attach microbiological spores time to an interdigitated sensor surface. The functionality and physical properties of APTES were studied on isolated sensor materials, namely silicon dioxide (SiO2) and platinum (Pt) as well as the combined material on sensor level. A predominant immobilization of spores could be demonstrated on SiO2 surfaces. Additionally, the impedance signal of APTES-functionalized biosensor chips has been investigated. Y1 - 2017 U6 - http://dx.doi.org/10.1016/j.electacta.2017.04.157 SN - 0013-4686 VL - 241 SP - 237 EP - 243 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Bronder, Thomas A1 - Poghossian, Arshak A1 - Keusgen, Michael A1 - Schöning, Michael Josef T1 - Label-free detection of double-stranded DNA molecules with polyelectrolyte-modified capacitive field-effect sensors T1 - Markierungsfreie Detektion doppelsträngiger DNA Moleküle mit Hilfe von Polyelektrolyt-modifizierten kapazitiven Feldeffekt-Sensoren JF - tm - Technisches Messen N2 - In this study, polyelectrolyte-modified field-effect-based electrolyte-insulator-semiconductor (EIS) devices have been used for the label-free electrical detection of double-stranded deoxyribonucleic acid (dsDNA)molecules. The sensor-chip functionalization with a positively charged polyelectrolyte layer provides the possibility of direct adsorptive binding of negatively charged target DNA oligonucleotides onto theSiO2-chip surface.EIS sensors can be utilized as a tool to detect surface-charge changes; the electrostatic adsorption of oligonucleotides onto the polyelectrolyte layer leads to a measureable surface-potential change. Signals of 39mV have been recorded after the incubation with the oligonucleotide solution. Besides the electrochemical experiments, the successful adsorption of dsDNA onto the polyelectrolyte layer has been verified via fluorescence microscopy. The presented results demonstrate that the signal recording of EISchips, which are modified with a polyelectrolyte layer, canbe used as a favorable approach for a fast, cheap and simple detection method for dsDNA. Y1 - 2017 U6 - http://dx.doi.org/10.1515/teme-2017-0015 VL - 84 IS - 10 SP - 628 EP - 634 PB - De Gruyter CY - Oldenbourg ER - TY - JOUR A1 - Muschallik, Lukas A1 - Molinnus, Denise A1 - Bongaerts, Johannes A1 - Pohl, Martina A1 - Wagner, Torsten A1 - Schöning, Michael Josef A1 - Siegert, Petra A1 - Selmer, Thorsten T1 - (R,R)-Butane-2,3-diol Dehydrogenase from Bacillus clausii DSM 8716T: Cloning and Expression of the bdhA-Gene, and Initial Characterization of Enzyme JF - Journal of Biotechnology N2 - The gene encoding a putative (R,R)-butane-2,3-diol dehydrogenase (bdhA) from Bacillus clausii DSM 8716T was isolated, sequenced and expressed in Escherichia coli. The amino acid sequence of the encoded protein is only distantly related to previously studied enzymes (identity 33–43%) and exhibited some uncharted peculiarities. An N-terminally StrepII-tagged enzyme variant was purified and initially characterized. The isolated enzyme catalyzed the (R)-specific oxidation of (R,R)- and meso-butane-2,3-diol to (R)- and (S)-acetoin with specific activities of 12 U/mg and 23 U/mg, respectively. Likewise, racemic acetoin was reduced with a specific activity of up to 115 U/mg yielding a mixture of (R,R)- and meso-butane-2,3-diol, while the enzyme reduced butane-2,3-dione (Vmax 74 U/mg) solely to (R,R)-butane-2,3-diol via (R)-acetoin. For these reactions only activity with the co-substrates NADH/NAD+ was observed. The enzyme accepted a selection of vicinal diketones, α-hydroxy ketones and vicinal diols as alternative substrates. Although the physiological function of the enzyme in B. clausii remains elusive, the data presented herein clearly demonstrates that the encoded enzyme is a genuine (R,R)-butane-2,3-diol dehydrogenase with potential for applications in biocatalysis and sensor development. Y1 - 2017 U6 - http://dx.doi.org/10.1016/j.jbiotec.2017.07.020 SN - 0168-1656 VL - 258 SP - 41 EP - 50 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Figueroa-Miranda, Gabriela A1 - Feng, Lingyan A1 - Shiu, Simon Chi-Chin A1 - Dirkzwager, Roderick Marshall A1 - Cheung, Yee-Wai A1 - Tanner, Julian Alexander A1 - Schöning, Michael Josef A1 - Offenhäusser, Andreas A1 - Mayer, Dirk T1 - Aptamer-based electrochemical biosensor for highly sensitive and selective malaria detection with adjustable dynamic response range and reusability JF - Sensor and Actuators B: Chemical N2 - Malaria infection remains a significant risk for much of the population of tropical and subtropical areas, particularly in developing countries. Therefore, it is of high importance to develop sensitive, accurate and inexpensive malaria diagnosis tests. Here, we present a novel aptamer-based electrochemical biosensor (aptasensor) for malaria detection by impedance spectroscopy, through the specific recognition between a highly discriminatory DNA aptamer and its target Plasmodium falciparum lactate dehydrogenase (PfLDH). Interestingly, due to the isoelectric point (pI) of PfLDH, the aptasensor response showed an adjustable detection range based on the different protein net-charge at variable pH environments. The specific aptamer recognition allows sensitive protein detection with an expanded detection range and a low detection limit, as well as a high specificity for PfLDH compared to analogous proteins. The specific feasibility of the aptasensor is further demonstrated by detection of the target PfLDH in human serum. Furthermore, the aptasensor can be easily regenerated and thus applied for multiple usages. The robustness, sensitivity, and reusability of the presented aptasensor make it a promising candidate for point-of-care diagnostic systems. Y1 - 2018 U6 - http://dx.doi.org/10.1016/j.snb.2017.07.117 SN - 0925-4005 VL - 255 IS - P1 SP - 235 EP - 243 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Morais, Paulo V. A1 - Gomes, Vanderley F., Jr. A1 - Silva, Anielle C. A. A1 - Dantas, Noelio O. A1 - Schöning, Michael Josef A1 - Siqueira, José R., Jr. T1 - Nanofilm of ZnO nanocrystals/carbon nanotubes as biocompatible layer for enzymatic biosensors in capacitive field-effect devices JF - Journal of Materials Science N2 - The incorporation of nanomaterials that are biocompatible with different types of biological compounds has allowed the development of a new generation of biosensors applied especially in the biomedical field. In particular, the integration of film-based nanomaterials employed in field-effect devices can be interesting to develop biosensors with enhanced properties. In this paper, we studied the fabrication of sensitive nanofilms combining ZnO nanocrystals and carbon nanotubes (CNTs), prepared by means of the layer-by-layer (LbL) technique, in a capacitive electrolyte-insulator-semiconductor (EIS) structure for detecting glucose and urea. The ZnO nanocrystals were incorporated in a polymeric matrix of poly(allylamine) hydrochloride (PAH), and arranged with multi-walled CNTs in a LbL PAH-ZnO/CNTs film architecture onto EIS chips. The electrochemical characterizations were performed by capacitance–voltage and constant capacitance measurements, while the morphology of the films was characterized by atomic force microscopy. The enzymes glucose oxidase and urease were immobilized on film’s surface for detection of glucose and urea, respectively. In order to obtain glucose and urea biosensors with optimized amount of sensitive films, we investigated the ideal number of bilayers for each detection system. The glucose biosensor showed better sensitivity and output signal for an LbL PAH-ZnO/CNTs nanofilm with 10 bilayers. On the other hand, the urea biosensor presented enhanced properties even for the first bilayer, exhibiting high sensitivity and output signal. The presence of the LbL PAH-ZnO/CNTs films led to biosensors with better sensitivity and enhanced response signal, demonstrating that the adequate use of nanostructured films is feasible for proof-of-concept biosensors with improved properties that may be employed for biomedical applications. Y1 - 2017 U6 - http://dx.doi.org/10.1007/s10853-017-1369-y SN - 1573-4803 VL - 52 IS - 20 SP - 12314 EP - 12325 PB - Springer CY - Berlin ER - TY - JOUR A1 - Dantism, Shahriar A1 - Takenaga, Shoko A1 - Wagner, Torsten A1 - Wagner, Patrick A1 - Schöning, Michael Josef T1 - Differential imaging of the metabolism of bacteria and eukaryotic cells based on light-addressable potentiometric sensors JF - Electrochimica Acta N2 - A light-addressable potentiometric sensor (LAPS) is a field-effect-based potentiometric sensor with an electrolyte/insulator/semiconductor (EIS) structure, which is able to monitor analyte concentrations of (bio-)chemical species in aqueous solutions in a spatially resolved way. Therefore, it is also an appropriate tool to record 2D-chemical images of concentration variations on the sensor surface. In the present work, two differential, LAPS-based measurement principles are introduced to determine the metabolic activity of Escherichia coli (E. coli) K12 and Chinese hamster ovary (CHO) cells as test microorganisms. Hereby, we focus on i) the determination of the extracellular acidification rate (ΔpH/min) after adding glucose solutions to the cell suspensions; and ii) recording the amplitude increase of the photocurrent (Iph) related to the produced acids from E. coli K12 bacteria and CHO cells on the sensor surface by 2D-chemical imaging. For this purpose, 3D-printed multi-chamber structures were developed and mounted on the planar sensor-chip surface to define four independent compartments, enabling differential measurements with varying cell concentrations. The differential concept allows eliminating unwanted drift effects and, with the four-chamber structures, measurements on the different cell concentrations were performed simultaneously, thus reducing also the overall measuring time. Y1 - 2017 U6 - http://dx.doi.org/10.1016/j.electacta.2017.05.196 SN - 0013-4686 VL - 246 SP - 234 EP - 241 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Jildeh, Zaid B. A1 - Kirchner, Patrick A1 - Oberländer, Jan A1 - Kremers, Alexander A1 - Wagner, Torsten A1 - Wagner, Patrick H. A1 - Schöning, Michael Josef T1 - FEM-based modeling of a calorimetric gas sensor for hydrogen peroxide monitoring JF - physica status solidi a : applications and materials sciences N2 - A physically coupled finite element method (FEM) model is developed to study the response behavior of a calorimetric gas sensor. The modeled sensor serves as a monitoring device of the concentration of gaseous hydrogen peroxide (H2 O2) in a high temperature mixture stream in aseptic sterilization processes. The principle of operation of a calorimetric H2 O2 sensor is analyzed and the results of the numerical model have been validated by using previously published sensor experiments. The deviation in the results between the FEM model and experimental data are presented and discussed. Y1 - 2017 U6 - http://dx.doi.org/10.1002/pssa.201600912 SN - 1862-6319 IS - Early View PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Molinnus, Denise A1 - Poghossian, Arshak A1 - Keusgen, Michael A1 - Katz, Evgeny A1 - Schöning, Michael Josef T1 - Coupling of Biomolecular Logic Gates with Electronic Transducers: From Single Enzyme Logic Gates to Sense/Act/Treat Chips JF - Electroanalysis N2 - The integration of biomolecular logic principles with electronic transducers allows designing novel digital biosensors with direct electrical output, logically triggered drug-release, and closed-loop sense/act/treat systems. This opens new opportunities for advanced personalized medicine in the context of theranostics. In the present work, we will discuss selected examples of recent developments in the field of interfacing enzyme logic gates with electrodes and semiconductor field-effect devices. Special attention is given to an enzyme OR/Reset logic gate based on a capacitive field-effect electrolyte-insulator-semiconductor sensor modified with a multi-enzyme membrane. Further examples are a digital adrenaline biosensor based on an AND logic gate with binary YES/NO output and an integrated closed-loop sense/act/treat system comprising an amperometric glucose sensor, a hydrogel actuator, and an insulin (drug) sensor. Y1 - 2017 U6 - http://dx.doi.org/10.1002/elan.201700208 SN - 1521-4109 VL - 29 IS - 8 SP - 1840 EP - 1849 PB - Wiley CY - Weinheim ER - TY - JOUR A1 - Arreola, Julio A1 - Keusgen, Michael A1 - Schöning, Michael Josef T1 - Effect of O2 plasma on properties of electrolyte-insulator-semiconductor structures JF - physica status solidi a : applications and materials sciences N2 - Prior to immobilization of biomolecules or cells onto biosensor surfaces, the surface must be physically or chemically activated for further functionalization. Organosilanes are a versatile option as they facilitate the immobilization through their terminal groups and also display self-assembly. Incorporating hydroxyl groups is one of the important methods for primary immobilization. This can be done, for example, with oxygen plasma treatment. However, this treatment can affect the performance of the biosensors and this effect is not quite well understood for surface functionalization. In this work, the effect of O2 plasma treatment on EIS sensors was investigated by means of electrochemical characterizations: capacitance–voltage (C–V) and constant capacitance (ConCap) measurements. After O2 plasma treatment, the potential of the EIS sensor dramatically shifts to a more negative value. This was successfully reset by using an annealing process. KW - surface functionalization KW - O2 plasma KW - hydroxylation KW - electrolyte-insulator semiconductor sensor (EIS) KW - annealing Y1 - 2017 U6 - http://dx.doi.org/10.1002/pssa.201700025 SN - 1862-6319 VL - 214 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Miyamoto, Ko-ichiro A1 - Hayashi, Kosuke A1 - Sakamoto, Azuma A1 - Werner, Frederik A1 - Wagner, Torsten A1 - Schöning, Michael Josef A1 - Yoshinobu, Tatsuo T1 - A high-Q resonance-mode measurement of EIS capacitive sensor by elimination of series resistance JF - Sensor and Actuators B: Chemical N2 - An EIS capacitive sensor is a semiconductor-based potentiometric sensor, which is sensitive to the ion concentration or pH value of the solution in contact with the sensing surface. To detect a small change in the ion concentration or pH, a small capacitance change must be detected. Recently, a resonance-mode measurement was proposed, in which an inductor was connected to the EIS capacitive sensor and the resonant frequency was correlated with the pH value. In this study, the Q factor of the resonant circuit was enhanced by canceling the internal resistance of the reference electrode and the internal resistance of the inductor coil with the help of a bypass capacitor and a negative impedance converter, respectively. 1% variation of the signal in the developed system corresponded to a pH change of 3.93 mpH, which was about 1/12 of the conventional method, suggesting a better performance in detection of a small pH change. KW - Negative impedance convertor KW - Resonance-mode measurement KW - Chemical sensor KW - EIS capacitive sensor Y1 - 2017 U6 - http://dx.doi.org/10.1016/j.snb.2017.03.002 SN - 0925-4005 VL - 248 SP - 1006 EP - 1010 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Werner, Frederik A1 - Miyamoto, Ko-ichiro A1 - Wagner, Torsten A1 - Schöning, Michael Josef A1 - Yoshinobu, Tatsuo T1 - Lateral resolution enhancement of pulse-driven light-addressable potentiometric sensor JF - Sensor and Actuators B: Chemical N2 - To study chemical and biological processes, spatially resolved determination of the concentrations of one or more analyte species is of distinct interest. With a light-addressable potentiometric sensor (LAPS), chemical images can be created, which visualize the concentration distribution above the sensor plate. One important challenge is to achieve a good lateral resolution in order to detect events that take place in a small and limited region. LAPS utilizes a focused light spot to address the measurement region. By moving this light spot along the semiconductor sensor plate, the concentration distribution can be observed. In this study, we show that utilizing a pulse as light excitation instead of a traditionally used continuously modulated light excitation, the lateral resolution can be improved by a factor of 6 or more. KW - Chemical images KW - LAPS KW - Light-addressable potentiometric sensor Y1 - 2017 U6 - http://dx.doi.org/10.1016/j.snb.2017.02.057 SN - 0925-4005 VL - 248 SP - 961 EP - 965 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Scholl, Fabio A1 - Morais, Paulo A1 - Gabriel, Rayla A1 - Schöning, Michael Josef A1 - Siqueira, Jose Roberto, Jr. A1 - Caseli, Luciano T1 - Carbon nanotubes arranged as smart interfaces in lipid Langmuir-Blodgett films enhancing the enzymatic properties of penicillinase for biosensing applications JF - Applied Materials & Interfaces N2 - In this paper, carbon nanotubes (CNTs) were incorporated in penicillinase-phospholipid Langmuir and Langmuir–Blodgett (LB) films to enhance the enzyme catalytic properties. Adsorption of the penicillinase and CNTs at dimyristoylphosphatidic acid (DMPA) monolayers at the air–water interface was investigated by surface pressure–area isotherms, vibrational spectroscopy, and Brewster angle microscopy. The floating monolayers were transferred to solid supports through the LB technique, forming mixed DMPA-CNTs-PEN films, which were investigated by quartz crystal microbalance, vibrational spectroscopy, and atomic force microscopy. Enzyme activity was studied with UV–vis spectroscopy and the feasibility of the supramolecular device nanostructured as ultrathin films were essayed in a capacitive electrolyte–insulator–semiconductor (EIS) sensor device. The presence of CNTs in the enzyme–lipid LB film not only tuned the catalytic activity of penicillinase but also helped conserve its enzyme activity after weeks, showing increased values of activity. Viability as penicillin sensor was demonstrated with capacitance/voltage and constant capacitance measurements, exhibiting regular and distinctive output signals over all concentrations used in this work. These results may be related not only to the nanostructured system provided by the film, but also to the synergism between the compounds on the active layer, leading to a surface morphology that allowed a fast analyte diffusion because of an adequate molecular accommodation, which also preserved the penicillinase activity. This work therefore demonstrates the feasibility of employing LB films composed of lipids, CNTs, and enzymes as EIS devices for biosensing applications. Y1 - 2017 U6 - http://dx.doi.org/10.1021/acsami.7b08095 SN - 1944-8252 VL - 9 IS - 36 SP - 31054 EP - 31066 PB - ACS CY - Washington ER - TY - JOUR A1 - Honarvarfard, Elham A1 - Gamella, Maria A1 - Poghossian, Arshak A1 - Schöning, Michael Josef A1 - Katz, Evgeny T1 - An enzyme-based reversible Controlled NOT (CNOT) logic gate operating on a semiconductor transducer JF - Applied Materials Today N2 - An enzyme-based biocatalytic system mimicking operation of a logically reversible Controlled NOT (CNOT) gate has been interfaced with semiconductor electronic transducers. Electrolyte–insulator–semiconductor (EIS) structures have been used to transduce chemical changes produced by the enzyme system to an electronically readable capacitive output signal using field-effect features of the EIS device. Two enzymes, urease and esterase, were immobilized on the insulating interface of EIS structure producing local pH changes performing XOR logic operation controlled by various combinations of the input signals represented by urea and ethyl butyrate. Another EIS transducer was functionalized with esterase only, thus performing Identity (ID) logic operation for the ethyl butyrate input. Both semiconductor devices assembled in parallel operated as a logically reversible CNOT gate. The present system, despite its simplicity, demonstrated for the first time logically reversible function of the enzyme system transduced electronically with the semiconductor devices. The biomolecular realization of a CNOT gate interfaced with semiconductors is promising for integration into complex biomolecular networks and future biosensor/biomedical applications. KW - Electrolyte–insulator–semiconductor KW - Capacitive field-effect KW - CNOT KW - XOR KW - Enzyme logic gate Y1 - 2017 U6 - http://dx.doi.org/10.1016/j.apmt.2017.08.003 SN - 2352-9407 VL - 9 SP - 266 EP - 270 PB - Elsevier CY - Amsterdam ER -