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 - 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 - 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 - CHAP A1 - Kasper, Katharina A1 - Schiffels, Johannes A1 - Krafft, Simone A1 - Kuperjans, Isabel A1 - Elbers, Gereon A1 - Selmer, Thorsten T1 - Biogas Production on Demand Regulated by Butyric Acid Addition T2 - IOP Conference Series: Earth and Environmental Science. Bd. 32 Y1 - 2016 U6 - http://dx.doi.org/10.1088/1755-1315/32/1/012009 SN - 1755-1315 N1 - ICARET 2016, International Conference on Advances in Renewable Energy and Technologies, Putrajaya, MY, Feb 23-25, 2016 VL - 32 SP - 012009/1 EP - 012009/4 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 - 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 - 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 - 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 - CHAP A1 - Poghossian, Arshak A1 - Bronder, Thomas A1 - Wu, Chunsheng A1 - Schöning, Michael Josef T1 - Label-free sensing of biomolecules by their intrinsic molecular charge using field-effect devices T2 - Semiconductor Micro- and Nanoelectonics : Proceedings of the tenth international conference, Yerevan, Armenia, September 11-13 Y1 - 2015 SN - 978-5-8084-1991-9 SP - 61 EP - 63 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 - 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 - CHAP A1 - Poghossian, Arshak A1 - Schusser, Sebastian A1 - Bäcker, M. A1 - Leinhos, Marcel A1 - Schöning, Michael Josef T1 - Real-time in-situ electrical monitoring of the degradation of biopolymers using semiconductor field-effect devices T2 - Biodegradable biopolymers. Vol. 1 Y1 - 2015 SN - 978-1-63483-632-6 SP - 135 EP - 153 PB - Nova Science Publ. CY - Hauppauge 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 - 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 - 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 - CHAP 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 - Experimental and numerical evaluation of interdigitated electrode array for monitoring gaseous sterilization processes T2 - 12. Dresdner Sensor-Symposium 2015 Y1 - 2015 U6 - http://dx.doi.org/10.5162/12dss2015/P3.11 SP - 163 EP - 168 ER - TY - CHAP A1 - Breuer, Lars A1 - Raue, Markus A1 - Mang, Thomas A1 - Schöning, Michael Josef A1 - Thoelen, Ronald A1 - Wagner, Torsten T1 - Light-stimulated hydrogel actuators with incorporated graphene oxide for microfluidic applications T2 - 12. Dresdner Sensor-Symposium 2015 Y1 - 2015 U6 - http://dx.doi.org/10.5162/12dss2015/P5.8 SP - 206 EP - 209 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 - 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 - 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 -