TY - JOUR A1 - Molinnus, Denise A1 - Iken, Heiko A1 - Johnen, Anna Lynn A1 - Richstein, Benjamin A1 - Hellmich, Lena A1 - Poghossian, Arshak A1 - Knoch, Joachim A1 - Schöning, Michael Josef T1 - Miniaturized pH-Sensitive Field-Effect Capacitors with Ultrathin Ta₂O₅ Films Prepared by Atomic Layer Deposition JF - physica status solidi (a) applications and materials science N2 - Miniaturized electrolyte–insulator–semiconductor capacitors (EISCAPs) with ultrathin gate insulators have been studied in terms of their pH-sensitive sensor characteristics: three different EISCAP systems consisting of Al–p-Si–Ta2O5(5 nm), Al–p-Si–Si3N4(1 or 2 nm)–Ta2O5 (5 nm), and Al–p-Si–SiO2(3.6 nm)–Ta2O5(5 nm) layer structures are characterized in buffer solution with different pH values by means of capacitance–voltage and constant capacitance method. The SiO2 and Si3N4 gate insulators are deposited by rapid thermal oxidation and rapid thermal nitridation, respectively, whereas the Ta2O5 film is prepared by atomic layer deposition. All EISCAP systems have a clear pH response, favoring the stacked gate insulators SiO2–Ta2O5 when considering the overall sensor characteristics, while the Si3N4(1 nm)–Ta2O5 stack delivers the largest accumulation capacitance (due to the lower equivalent oxide thickness) and a higher steepness in the slope of the capacitance–voltage curve among the studied stacked gate insulator systems. KW - atomic layer deposition KW - capacitive field-effect sensors KW - pH sensors KW - ultrathin gate insulators Y1 - 2022 U6 - http://dx.doi.org/10.1002/pssa.202100660 SN - 1862-6319 VL - 219 IS - 8 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Molinnus, Denise A1 - Drinic, Aleksander A1 - Iken, Heiko A1 - Kröger, Nadja A1 - Zinser, Max A1 - Smeets, Ralf A1 - Köpf, Marius A1 - Kopp, Alexander A1 - Schöning, Michael Josef T1 - Towards a flexible electrochemical biosensor fabricated from biocompatible Bombyx mori silk JF - Biosensors and Bioelectronics Y1 - 2021 U6 - http://dx.doi.org/10.1016/j.bios.2021.113204 SN - 0956-5663 VL - 183 IS - Art. 113204 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Wert, Stefan A1 - Iken, Heiko A1 - Schöning, Michael Josef A1 - Matysik, Frank-Michael T1 - Development of a temperature‐pulse enhanced electrochemical glucose biosensor and characterization of its stability via scanning electrochemical microscopy JF - Electroanalysis N2 - Glucose oxidase (GOx) is an enzyme frequently used in glucose biosensors. As increased temperatures can enhance the performance of electrochemical sensors, we investigated the impact of temperature pulses on GOx that was drop-coated on flattened Pt microwires. The wires were heated by an alternating current. The sensitivity towards glucose and the temperature stability of GOx was investigated by amperometry. An up to 22-fold increase of sensitivity was observed. Spatially resolved enzyme activity changes were investigated via scanning electrochemical microscopy. The application of short (<100 ms) heat pulses was associated with less thermal inactivation of the immobilized GOx than long-term heating. Y1 - 2021 U6 - http://dx.doi.org/10.1002/elan.202100089 SN - 1521-4109 IS - Early View PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Givanoudi, Stella A1 - Cornelis, Peter A1 - Rasschaert, Geertrui A1 - Wackers, Gideon A1 - Iken, Heiko A1 - Rolka, David A1 - Yongabi, Derick A1 - Robbens, Johan A1 - Schöning, Michael Josef A1 - Heyndrickx, Marc A1 - Wagner, Patrick T1 - Selective Campylobacter detection and quantification in poultry: A sensor tool for detecting the cause of a common zoonosis at its source JF - Sensors and Actuators B: Chemical Y1 - 2021 U6 - http://dx.doi.org/10.1016/j.snb.2021.129484 SN - 0925-4005 IS - In Press, Journal Pre-proof SP - Article 129484 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Cornelis, Peter A1 - Givanoudi, Stella A1 - Yongabi, Derick A1 - Iken, Heiko A1 - Duwé, Sam A1 - Deschaume, Olivier A1 - Robbens, Johan A1 - Dedecker, Peter A1 - Bartic, Carmen A1 - Wübbenhorst, Michael A1 - Schöning, Michael Josef A1 - Heyndrickx, Marc A1 - Wagner, Patrick T1 - Sensitive and specific detection of E. coli using biomimetic receptors in combination with a modified heat-transfer method JF - Biosensors and Bioelectronics Y1 - 2019 U6 - http://dx.doi.org/10.1016/j.bios.2019.04.026 SN - 0956-5663 VL - 136 SP - 97 EP - 105 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Iken, Heiko A1 - Bronder, Thomas A1 - Goretzki, Alexander A1 - Kriesel, Jana A1 - Ahlborn, Kristina A1 - Gerlach, Frank A1 - Vonau, Winfried A1 - Zander, Willi A1 - Schubert, Jürgen A1 - Schöning, Michael Josef T1 - Development of a Combined pH- and Redox-Sensitive Bi-Electrode Glass Thin-Film Sensor JF - physica status solidi a : applications and materials sciences Y1 - 2019 U6 - http://dx.doi.org/10.1002/pssa.201900114 SN - 1862-6319 VL - 216 IS - 12 SP - 1 EP - 8 PB - Wiley 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 - 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 - 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 - 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 -