TY - JOUR A1 - Rabehi, Amine A1 - Garlan, Benjamin A1 - Achtsnicht, Stefan A1 - Krause, Hans-Joachim A1 - Offenhäusser, Andreas A1 - Ngo, Kieu A1 - Neveu, Sophie A1 - Graff-Dubois, Stephanie A1 - Kokabi, Hamid T1 - Magnetic detection structure for Lab-on-Chip applications based on the frequency mixing technique JF - Sensors N2 - A magnetic frequency mixing technique with a set of miniaturized planar coils was investigated for use with a completely integrated Lab-on-Chip (LoC) pathogen sensing system. The system allows the detection and quantification of superparamagnetic beads. Additionally, in terms of magnetic nanoparticle characterization ability, the system can be used for immunoassays using the beads as markers. Analytical calculations and simulations for both excitation and pick-up coils are presented; the goal was to investigate the miniaturization of simple and cost-effective planar spiral coils. Following these calculations, a Printed Circuit Board (PCB) prototype was designed, manufactured, and tested for limit of detection, linear response, and validation of theoretical concepts. Using the magnetic frequency mixing technique, a limit of detection of 15 µg/mL of 20 nm core-sized nanoparticles was achieved without any shielding. KW - Lab-on-Chip KW - magnetic sensing KW - frequency mixing KW - superparamagnetic nanoparticles KW - magnetic beads Y1 - 2018 U6 - http://dx.doi.org/10.3390/s18061747 SN - 1424-8220 VL - 18 IS - 6 PB - MDPI CY - Basel ER - TY - CHAP A1 - Schöning, Michael Josef A1 - Wagner, Torsten A1 - Poghossian, Arshak A1 - Miyamoto, K.I. A1 - Werner, C.F. A1 - Krause, S. A1 - Yoshinobu, T. T1 - Light-addressable potentiometric sensors for (bio-)chemical sensing and imaging T2 - Encyclopedia of Interfacial Chemistry: Surface Science and Electrochemistry. Vol. 7 Y1 - 2018 SN - 9780128097397 SP - 295 EP - 308 PB - Elsevier CY - Amsterdam ER - TY - BOOK A1 - Molinnus, Denise T1 - Integration of biomolecular logic principles with electronic transducers on a chip Y1 - 2018 PB - Philipps-Universität / Fachbereich Pharmazie CY - Marburg/Lahn ER - TY - CHAP A1 - Schöning, Michael Josef A1 - Poghossian, Arshak T1 - Enzyme und Biosensorik T2 - Einführung in die Enzymtechnologie N2 - Enzymbasierte Biosensoren finden seit mehr als fünf Jahrzehnten einen prosperierenden Wachstumsmarkt und werden zunehmend auch in biotechnologischen Prozessen eingesetzt. In diesem Kapitel werden, ausgehend vom Sensorbegriff und typischen Kenngrößen für Biosensoren (Abschn. 18.1), elektrochemische Enzym-Biosensoren vorgestellt und deren typischen Einsatzgebiete diskutiert (Abschn. 18.2). Ein Blick über den „Tellerrand“ hinaus zeigt alternative Transduktorprinzipien (Abschn. 18.3) und führt abschließend in aktuelle Forschungstrends ein (Abschn. 18.4). Y1 - 2018 SN - 978-3-662-57619-9 U6 - http://dx.doi.org/10.1007/978-3-662-57619-9_18 SP - 323 EP - 347 PB - Springer Spektrum CY - Berlin ER - TY - CHAP A1 - Yoshinobu, Tatsuo A1 - Krause, Steffi A1 - Miyamoto, Ko-ichiro A1 - Werner, Frederik A1 - Poghossian, Arshak A1 - Wagner, Torsten A1 - Schöning, Michael Josef T1 - (Bio-)chemical Sensing and Imaging by LAPS and SPIM T2 - Label-free biosensing: advanced materials, devices and applications N2 - The light-addressable potentiometric sensor (LAPS) and scanning photo-induced impedance microscopy (SPIM) are two closely related methods to visualise the distributions of chemical species and impedance, respectively, at the interface between the sensing surface and the sample solution. They both have the same field-effect structure based on a semiconductor, which allows spatially resolved and label-free measurement of chemical species and impedance in the form of a photocurrent signal generated by a scanning light beam. In this article, the principles and various operation modes of LAPS and SPIM, functionalisation of the sensing surface for measuring various species, LAPS-based chemical imaging and high-resolution sensors based on silicon-on-sapphire substrates are described and discussed, focusing on their technical details and prospective applications. KW - Chemical imaging KW - Field-effect device KW - Light-addressable potentiometric sensor KW - Potentiometry Y1 - 2018 SN - 978-3-319-75219-8 SP - 103 EP - 132 PB - Springer CY - Cham ER - TY - BOOK A1 - Schöning, Michael Josef A1 - Poghossian, Arshak T1 - Label-free biosensing: advanced materials, devices and applications Y1 - 2018 SN - 978-3-319-75219-8 PB - Springer CY - Cham ER - TY - JOUR A1 - Rodrigues, Raul T. A1 - Morais, Paulo V. A1 - Nordi, Cristina S. F. A1 - Schöning, Michael Josef A1 - Siqueira Jr., José R. A1 - Caseli, Luciano T1 - Carbon Nanotubes and Algal Polysaccharides To Enhance the Enzymatic Properties of Urease in Lipid Langmuir-Blodgett Films JF - Langmuir N2 - Algal polysaccharides (extracellular polysaccharides) and carbon nanotubes (CNTs) were adsorbed on dioctadecyldimethylammonium bromide Langmuir monolayers to serve as a matrix for the incorporation of urease. The physicochemical properties of the supramolecular system as a monolayer at the air–water interface were investigated by surface pressure–area isotherms, surface potential–area isotherms, interfacial shear rheology, vibrational spectroscopy, and Brewster angle microscopy. The floating monolayers were transferred to hydrophilic solid supports, quartz, mica, or capacitive electrolyte–insulator–semiconductor (EIS) devices, through the Langmuir–Blodgett (LB) technique, forming mixed films, which were investigated by quartz crystal microbalance, fluorescence spectroscopy, and field emission gun scanning electron microscopy. The enzyme activity was studied with UV–vis spectroscopy, and the feasibility of the thin film as a urea sensor was essayed in an EIS sensor device. The presence of CNT in the enzyme–lipid LB film not only tuned the catalytic activity of urease but also helped to conserve its enzyme activity. Viability as a urease 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 are related to the synergism between the compounds on the active layer, leading to a surface morphology that allowed fast analyte diffusion owing to an adequate molecular accommodation, which also preserved the urease activity. This work demonstrates the feasibility of employing LB films composed of lipids, CNT, algal polysaccharides, and enzymes as EIS devices for biosensing applications. Y1 - 2018 U6 - http://dx.doi.org/10.1021/acs.langmuir.7b04317 SN - 1520-5827 VL - 34 IS - 9 SP - 3082 EP - 3093 PB - ACS Publications CY - Washington, DC ER - TY - JOUR A1 - Röhlen, Desiree A1 - Pilas, Johanna A1 - Dahmen, Markus A1 - Keusgen, Michael A1 - Selmer, Thorsten A1 - Schöning, Michael Josef T1 - Toward a Hybrid Biosensor System for Analysis of Organic and Volatile Fatty Acids in Fermentation Processes JF - Frontiers in Chemistry N2 - Monitoring of organic acids (OA) and volatile fatty acids (VFA) is crucial for the control of anaerobic digestion. In case of unstable process conditions, an accumulation of these intermediates occurs. In the present work, two different enzyme-based biosensor arrays are combined and presented for facile electrochemical determination of several process-relevant analytes. Each biosensor utilizes a platinum sensor chip (14 × 14 mm²) with five individual working electrodes. The OA biosensor enables simultaneous measurement of ethanol, formate, d- and l-lactate, based on a bi-enzymatic detection principle. The second VFA biosensor provides an amperometric platform for quantification of acetate and propionate, mediated by oxidation of hydrogen peroxide. The cross-sensitivity of both biosensors toward potential interferents, typically present in fermentation samples, was investigated. The potential for practical application in complex media was successfully demonstrated in spiked sludge samples collected from three different biogas plants. Thereby, the results obtained by both of the biosensors were in good agreement to the applied reference measurements by photometry and gas chromatography, respectively. The proposed hybrid biosensor system was also used for long-term monitoring of a lab-scale biogas reactor (0.01 m³) for a period of 2 months. In combination with typically monitored parameters, such as gas quality, pH and FOS/TAC (volatile organic acids/total anorganic carbonate), the amperometric measurements of OA and VFA concentration could enhance the understanding of ongoing fermentation processes. Y1 - 2018 U6 - http://dx.doi.org/10.3389/fchem.2018.00284 IS - 6 PB - Frontiers CY - Lausanne ER - TY - JOUR A1 - Miyamoto, Koichiro A1 - Seki, Kosuke A1 - Suto, Takeyuki A1 - Werner, Frederik A1 - Wagner, Torsten A1 - Schöning, Michael Josef A1 - Yoshinobu, Tatsuo T1 - Improved spatial resolution of the chemical imaging sensor with a hybrid illumination that suppresses lateral diffusion of photocarriers JF - Sensor and Actuators B: Chemical N2 - The chemical imaging sensor is a semiconductor-based chemical sensor capable of visualizing pH and ion distributions. The spatial resolution depends on the lateral diffusion of photocarriers generated by illumination of the semiconductor substrate. In this study, two types of optical setups, one based on a bundle of optical fibers and the other based on a binocular tube head, were developed to project a hybrid illumination of a modulated light beam and a ring-shaped constant illumination onto the sensor plate. An improved spatial resolution was realized by the ring-shaped constant illumination, which suppressed lateral diffusion of photocarriers by enhanced recombination due to the increased carrier concentration. Y1 - 2018 U6 - http://dx.doi.org/10.1016/j.snb.2018.07.016 SN - 0925-4005 VL - 273 SP - 1328 EP - 1333 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Jildeh, Zaid B. A1 - Oberländer, Jan A1 - Kirchner, Patrick A1 - Keusgen, Michael A1 - Wagner, Patrick H. A1 - Schöning, Michael Josef T1 - Experimental and Numerical Analyzes of a Sensor Based on Interdigitated Electrodes for Studying Microbiological Alterations JF - physica status solidi (a): applications and materials science N2 - In this work, a cell-based biosensor to evaluate the sterilization efficacy of hydrogen peroxide vapor sterilization processes is characterized. The transducer of the biosensor is based on interdigitated gold electrodes fabricated on an inert glass substrate. Impedance spectroscopy is applied to evaluate the sensor behavior and the alteration of test microorganisms due to the sterilization process. These alterations are related to changes in relative permittivity and electrical conductivity of the bacterial spores. Sensor measurements are conducted with and without bacterial spores (Bacillus atrophaeus), as well as after an industrial sterilization protocol. Equivalent two-dimensional numerical models based on finite element method of the periodic finger structures of the interdigitated gold electrodes are designed and validated using COMSOL® Multiphysics software by the application of known dielectric properties. The validated models are used to compute the electrical properties at different sensor states (blank, loaded with spores, and after sterilization). As a final result, we will derive and tabulate the frequency-dependent electrical parameters of the spore layer using a novel model that combines experimental data with numerical optimization techniques. Y1 - 2018 U6 - http://dx.doi.org/10.1002/pssa.201700920 SN - 1862-6319 VL - 215 IS - 15 PB - Wiley-VCH CY - Weinheim ER -