TY  - JOUR
A1  - Dantism, Shahriar
A1  - Röhlen, Desiree
A1  - Wagner, Torsten
A1  - Wagner, Patrick
A1  - Schöning, Michael Josef
T1  - Optimization of Cell-Based Multi-Chamber LAPS Measurements Utilizing FPGA-Controlled Laser-Diode Modules
JF  - physica status solidi a : applications and materials sciences
N2  - A light-addressable potentiometric sensor (LAPS) is a field-effect-based potentiometric device, which detects concentration changes of an analyte solution on the sensor surface in a spatially resolved way. It uses a light source to generate electron–hole pairs inside the semiconductor, which are separated in the depletion region due to an applied bias voltage across the sensor structure and hence, a surface-potential-dependent photocurrent can be read out. However, depending on the beam angle of the light source, scattering effects can occur, which influence the recorded signal in LAPS-based differential measurements. To solve this problem, a novel illumination unit based on a field programmable gate array (FPGA) consisting of 16 small-sized tunable infrared laser-diode modules (LDMs) is developed. Due to the improved focus of the LDMs with a beam angle of only 2 mrad, undesirable scattering effects are minimized. Escherichia coli (E. coli) K12 bacteria are used as a test microorganism to study the extracellular acidification on the sensor surface. Furthermore, a salt bridge chamber is built up and integrated with the LAPS system enabling multi-chamber differential measurements with a single Ag/AgCl reference electrode.
Y1  - 2018
U6  - http://dx.doi.org/10.1002/pssa.201800058
SN  - 1862-6319
VL  - 215
IS  - 15
SP  - Article number 1800058
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  - Dantism, Shahriar
A1  - Takenaga, Shoko
A1  - Wagner, Torsten
A1  - Wagner, Patrick
A1  - Schöning, Michael Josef
T1  - Differential imaging of the metabolism of bacteria and eukaryotic cells based on light-addressable potentiometric sensors
JF  - Electrochimica Acta
N2  - 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.
Y1  - 2017
U6  - http://dx.doi.org/10.1016/j.electacta.2017.05.196
SN  - 0013-4686
VL  - 246
SP  - 234
EP  - 241
PB  - Elsevier
CY  - Amsterdam
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  - Doll, T.
A1  - Scharnagl, K.
A1  - Winter, R.
A1  - Bögner, M.
A1  - Eisele, I.
A1  - Ostrik, B.
A1  - Schöning, Michael Josef
T1  - Work function gas sensors - reference layers and signal analysis
JF  - Eurosensors XII : proceedings of the 12th European Conference on Solid-State Transducers and the 9th UK Conference on Sensors and their Applications, Southampton, UK, 13 - 16 September 1998 / ed. by N. M. White ; Vol. 1
Y1  - 1998
SN  - 0-7503-0595-9
N1  - Eurosensors ; (12, 1998, Southampton) ; UK Conference on Sensors and Their Applications ; (9, 1998, Southampton)
SP  - 143
EP  - 146
PB  - Inst. of Physics Publ.
CY  - Bristol [u.a.]
ER  - 
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  - Emons, H.
A1  - Baade, A.
A1  - Schöning, Michael Josef
T1  - Voltammetric determination of heavy metals in microvolumes of rain water
JF  - Electroanalysis. 12 (2000), H. 15
Y1  - 2000
SN  - 1040-0397
SP  - 1171
EP  - 1176
ER  - 
TY  - JOUR
A1  - Emons, H.
A1  - Glück, O.
A1  - Hüllenkremer, B.
A1  - Schöning, Michael Josef
T1  - Voltohmmetry as an alternative detection method at polycrystalline metal film electrodes
JF  - Electroanalysis. 13 (2001), H. 8-9
Y1  - 2001
SN  - 1040-0397
SP  - 677
EP  - 680
ER  - 
TY  - JOUR
A1  - Emons, H.
A1  - Glück, O.
A1  - Schöning, Michael Josef
T1  - Voltohmmetry – An alternative detection principle at ultrathin metal electrodes in solution
JF  - Chemical and biological sensors and analytical methods : proceedings of the international symposium / Sensor, Physical Electrochemistry, and Organic and Biological Electrochemistry Divisions. Ed.: M. Butler
Y1  - 2001
SN  - 1-56677-351-2
N1  - International Symposium: Chemical and Biological Sensors and Analytical Methods ; (2 : 2001.)
SP  - 1
EP  - 3
PB  - Electrochemical Society
CY  - Pennington, NJ
ER  - 
TY  - JOUR
A1  - Emons, H.
A1  - Hüllenkremer, B.
A1  - Schöning, Michael Josef
T1  - Detection of metal ions in aqueous solutions by voltohmmetry
JF  - Fresenius' Journal of Analytical Chemistry. 369 (2001), H. 1
Y1  - 2001
SN  - 0937-0633
SP  - 42
EP  - 46
ER  -