@inproceedings{PoghossianBronderSchejaetal.2016, author = {Poghossian, Arshak and Bronder, Thomas and Scheja, S. and Wu, Chunsheng and Metzger-Boddien, C. and Keusgen, M. and Sch{\"o}ning, Michael Josef}, title = {Label-free Electrostatic Detection of DNA Amplification by PCR Using Capacitive Field-effect Devices}, series = {Procedia Engineering}, volume = {Vol. 168}, booktitle = {Procedia Engineering}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1877-7058}, doi = {10.1016/j.proeng.2016.11.512}, pages = {514 -- 517}, year = {2016}, abstract = {A capacitive field-effect EIS (electrolyte-insulator-semiconductor) sensor modified with a positively charged weak polyelectrolyte of poly(allylamine hydrochloride) (PAH)/single-stranded probe DNA (ssDNA) bilayer has been used for a label-free electrostatic detection of pathogen-specific DNA amplification via polymerase chain reaction (PCR). The sensor is able to distinguish between positive and negative PCR solutions, to detect the existence of target DNA amplicons in PCR samples and thus, can be used as tool for a quick verification of DNA amplification and the successful PCR process.}, language = {en} } @article{WuPoghossianBronderetal.2016, author = {Wu, Chunsheng and Poghossian, Arshak and Bronder, Thomas and Sch{\"o}ning, Michael Josef}, title = {Sensing of double-stranded DNA molecules by their intrinsic molecular charge using the light-addressable potentiometric sensor}, series = {Sensors and Actuators B: Chemical}, journal = {Sensors and Actuators B: Chemical}, number = {229}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0925-4005}, doi = {10.1016/j.snb.2016.02.004}, pages = {506 -- 512}, year = {2016}, abstract = {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.}, language = {en} } @article{YoshinobuMiyamotoWerneretal.2017, author = {Yoshinobu, Tatsuo and Miyamoto, Ko-ichiro and Werner, Frederik and Poghossian, Arshak and Wagner, Torsten and Sch{\"o}ning, Michael Josef}, title = {Light-addressable potentiometric sensors for quantitative spatial imaging of chemical species}, series = {Annual Review of Analytical Chemistry}, volume = {10}, journal = {Annual Review of Analytical Chemistry}, publisher = {Annual Reviews}, address = {Palo Alto, Calif.}, issn = {1936-1327}, doi = {10.1146/annurev-anchem-061516-045158}, pages = {225 -- 246}, year = {2017}, abstract = {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.}, language = {en} } @article{BaeckerRakowskiKrappenetal.2017, author = {B{\"a}cker, M. and Rakowski, D. and Krappen, E. and Sch{\"o}ning, Michael Josef}, title = {Reinigungsprozesse in der Lebensmittelindustrie. Entwicklung eines Demonstrators zur {\"U}berwachung}, series = {GIT Labor-Fachzeitschrift}, volume = {61}, journal = {GIT Labor-Fachzeitschrift}, number = {8}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {0016-3538}, pages = {26 -- 28}, year = {2017}, language = {de} } @article{SousaSiqueiraVerciketal.2017, author = {Sousa, Marcos A. M. and Siqueira, Jose R. Jr. and Vercik, Andres and Sch{\"o}ning, Michael Josef and Oliveira, Osvaldo N. Jr.}, title = {Determining the optimized layer-by-layer film architecture with dendrimer/carbon nanotubes for field-effect sensors}, series = {IEEE Sensors Journal}, volume = {17}, journal = {IEEE Sensors Journal}, number = {6}, publisher = {IEEE}, address = {New York}, issn = {1558-1748}, doi = {10.1109/JSEN.2017.2653238}, pages = {1735 -- 1740}, year = {2017}, abstract = {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.}, language = {en} } @article{ArreolaOberlaenderMaetzkowetal.2017, author = {Arreola, Julio and Oberl{\"a}nder, Jan and M{\"a}tzkow, M. and Keusgen, Michael and Sch{\"o}ning, Michael Josef}, title = {Surface functionalization for spore-based biosensors with organosilanes}, series = {Electrochimica Acta}, volume = {241}, journal = {Electrochimica Acta}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0013-4686}, doi = {10.1016/j.electacta.2017.04.157}, pages = {237 -- 243}, year = {2017}, abstract = {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.}, language = {en} } @article{DantismTakenagaWagneretal.2017, author = {Dantism, Shahriar and Takenaga, Shoko and Wagner, Torsten and Wagner, Patrick and Sch{\"o}ning, Michael Josef}, title = {Differential imaging of the metabolism of bacteria and eukaryotic cells based on light-addressable potentiometric sensors}, series = {Electrochimica Acta}, volume = {246}, journal = {Electrochimica Acta}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0013-4686}, doi = {10.1016/j.electacta.2017.05.196}, pages = {234 -- 241}, year = {2017}, abstract = {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.}, language = {en} } @article{JildehKirchnerOberlaenderetal.2017, author = {Jildeh, Zaid B. and Kirchner, Patrick and Oberl{\"a}nder, Jan and Kremers, Alexander and Wagner, Torsten and Wagner, Patrick H. and Sch{\"o}ning, Michael Josef}, title = {FEM-based modeling of a calorimetric gas sensor for hydrogen peroxide monitoring}, series = {physica status solidi a : applications and materials sciences}, journal = {physica status solidi a : applications and materials sciences}, number = {Early View}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1862-6319}, doi = {10.1002/pssa.201600912}, year = {2017}, abstract = {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.}, language = {en} } @article{ArreolaKeusgenSchoening2017, author = {Arreola, Julio and Keusgen, Michael and Sch{\"o}ning, Michael Josef}, title = {Effect of O2 plasma on properties of electrolyte-insulator-semiconductor structures}, series = {physica status solidi a : applications and materials sciences}, volume = {214}, journal = {physica status solidi a : applications and materials sciences}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1862-6319}, doi = {10.1002/pssa.201700025}, pages = {Artikel 1700025}, year = {2017}, abstract = {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.}, language = {en} } @article{MiyamotoHayashiSakamotoetal.2017, author = {Miyamoto, Ko-ichiro and Hayashi, Kosuke and Sakamoto, Azuma and Werner, Frederik and Wagner, Torsten and Sch{\"o}ning, Michael Josef and Yoshinobu, Tatsuo}, title = {A high-Q resonance-mode measurement of EIS capacitive sensor by elimination of series resistance}, series = {Sensor and Actuators B: Chemical}, volume = {248}, journal = {Sensor and Actuators B: Chemical}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0925-4005}, doi = {10.1016/j.snb.2017.03.002}, pages = {1006 -- 1010}, year = {2017}, abstract = {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.}, language = {en} }