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  - JOUR
A1  - Brahma, Aischarya
A1  - Musio, Biagia
A1  - Ismayilova, Uliviya
A1  - Nikbin, Nikzad
A1  - Kamptmann, Sonja B.
A1  - Siegert, Petra
A1  - Jeromin, Günter Erich
A1  - Ley, Steven
A1  - Pohl, Martina
T1  - An orthogonal biocatalytic approach for the safe generation and use of HCN in a multi-step continuous preparation of chiral O-acetylcyanohydrins
JF  - Synlett
Y1  - 2015
U6  - http://dx.doi.org/10.1055/s-0035-1560644
SN  - 0936-5214 (Print) ; 1437-2096 (e-Journal)
IS  - Publ. online 29.09.2015
PB  - Thieme
CY  - Stuttgart
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  - 
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  - 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  - 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  - 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  - 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  - Voigt, Birgit
A1  - Albrecht, Dirk
A1  - Sievers, Susanne
A1  - Becher, Dörte
A1  - Bongaerts, Johannes
A1  - Evers, Stefan
A1  - Schweder, Thomas
A1  - Maurer, Karl-Heinz
A1  - Hecker, Michael
T1  - High-resolution proteome maps of Bacillus licheniformis cells growing in minimal medium
JF  - Proteomics
Y1  - 2015
U6  - http://dx.doi.org/10.1002/pmic.201400504
SN  - 1615-9861
VL  - 15
IS  - 15
SP  - 2629
EP  - 2633
PB  - Wiley
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Schiffels, Johannes
A1  - Selmer, Thorsten
T1  - A flexible toolbox to study protein-assisted metalloenzyme assembly in vitro
JF  - Biotechnology and Bioengineering
Y1  - 2015
U6  - http://dx.doi.org/10.1002/bit.25658
SN  - 1097-0290
VL  - 112
IS  - 11
SP  - 2360
EP  - 2372
PB  - Wiley
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  - 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  - 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  - 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  - 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  - 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  -