TY  - JOUR
A1  - Werner, Frederik
A1  - Groebel, Simone
A1  - Wagner, Torsten
A1  - Yoshinobu, Tatsuo
A1  - Selmer, Thorsten
A1  - Baumann, Marcus
A1  - Schöning, Michael Josef
T1  - Überwachung der metabolischen Aktivität von Mikroorganismen zur Kontrolle des biologischen Prozesses im Biogasfermenter
JF  - Biogas 2011 : Energieträger der Zukunft ; 6. Fachtagung, Fachtagung Braunschweig, 08. und 09. Juni 2011 / VDI Energie und Umwelt
Y1  - 2011
SN  - 978-3-18-092121-1
N1  - Gesellschaft Energie und Umwelt ; Fachtagung Biogas ; (6 : ; 2011.06.08-09 : ; Braunschweig) ; 	VDI-Berichte ; 2121
SP  - 285
EP  - 286
PB  - VDI-Verl.
CY  - Düsseldorf
ER  - 
TY  - JOUR
A1  - Wagner, Torsten
A1  - Miyamoto, K.
A1  - Werner, Frederik
A1  - Schöning, Michael Josef
A1  - Yoshinobu, T.
T1  - Utilising Digital Micro-Mirror Device (DMD) as Scanning Light Source for Light-Addressable Potentiometric Sensors (LAPS)
Y1  - 2011
U6  - http://dx.doi.org/10.1166/sl.2011.1620
VL  - 9
IS  - 2
SP  - 812
EP  - 815
PB  - American Scientific Publishers
CY  - Stevenson Ranch, Calif.
ER  - 
TY  - JOUR
A1  - Siqueira, Jose R.
A1  - Maki, Rafael M.
A1  - Paulovich, Fernando V.
A1  - Werner, Frederik
A1  - Poghossian, Arshak
A1  - Oliveira, Maria C. F. de
A1  - Zucolotto, Valtencir
A1  - Oliveira, Osvaldo N. Jr.
A1  - Schöning, Michael Josef
T1  - Use of Information Visualization Methods Eliminating Cross Talk in Multiple Sensing Units Investigated for a Light-Addressable Potentiometric Sensor
JF  - Analytical Chemistry  (2010)
Y1  - 2010
SN  - 0003-2700
SP  - 61
EP  - 65
ER  - 
TY  - JOUR
A1  - Poghossian, Arshak
A1  - Werner, Frederik
A1  - Buniatyan, V. V.
A1  - Wagner, Torsten
A1  - Miamoto, K.
A1  - Yoshinobu, T.
A1  - Schöning, Michael Josef
T1  - Towards addressability of light-addressable potentiometric sensors: Shunting effect of non-illuminated region and cross-talk
JF  - Sensor and Actuators B: Chemical
N2  - The LAPS (light-addressable potentiometric sensor) platform is one of the most attractive approaches for chemical and biological sensing with many applications ranging from pH and ion/analyte concentration measurements up to cell metabolism detection and chemical imaging. However, although it is generally accepted that LAPS measurements are spatially resolved, the light-addressability feature of LAPS devices has not been discussed in detail so far. In this work, an extended electrical equivalent-circuit model of the LAPS has been presented, which takes into account possible cross-talk effects due to the capacitive coupling of the non-illuminated region. A shunting effect of the non-illuminated area on the measured photocurrent and addressability of LAPS devices has been studied. It has been shown, that the measured photocurrent will be determined not only by the local interfacial potential in the illuminated region but also by possible interfacial potential changes in the non-illuminated region, yielding cross-talk effects. These findings were supported by the experimental investigations of a penicillin-sensitive multi-spot LAPS and a metal-insulator-semiconductor LAPS as model systems.
Y1  - 2017
U6  - http://dx.doi.org/10.1016/j.snb.2017.01.047
SN  - 0925-4005
IS  - 244
SP  - 1071
EP  - 1079
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - CHAP
A1  - Werner, Frederik
A1  - Yoshinobu, T.
A1  - Miyamoto, K.
A1  - Schöning, Michael Josef
A1  - Wagner, Torsten
T1  - Semiconductor-based sensors for imaging of chemical processes
T2  - Sensoren und Messsysteme 2014 ; Beiträge der 17. GMA/ITG-Fachtagung vom 3. bis 4. Juni 2014 in Nürnberg. (ITG-Fachbericht ; 250)
Y1  - 2014
SN  - 978-3-8007-3622-5
SP  - 1
EP  - 5
PB  - VDE-Verl.
CY  - Düsseldorf
ER  - 
TY  - CHAP
A1  - Miyamoto, Ko-ichiro
A1  - Suto, Takeyuki
A1  - Werner, Frederik
A1  - Wagner, Torsten
A1  - Schöning, Michael Josef
A1  - Yoshinobu, Tatsuo
T1  - Restraining the Diffusion of Photocarriers to Improve the Spatial Resolution of the Chemical Imaging Sensor
T2  - MDPI Proceedings
Y1  - 2017
U6  - http://dx.doi.org/10.3390/proceedings1040477
N1  - Eurosensors 2017 Conference, Paris, France, 3–6 September 2017
VL  - 1
IS  - 4
ER  - 
TY  - JOUR
A1  - Werner, Frederik
A1  - Groebel, Simone
A1  - Krumbe, Christoph
A1  - Wagner, Torsten
A1  - Selmer, Thorsten
A1  - Yoshinobu, Tatsuo
A1  - Baumann, Marcus
A1  - Schöning, Michael Josef
T1  - Nutrient concentration-sensitive microorganism-based biosensor
JF  - Physica Status Solidi (a)
Y1  - 2012
U6  - http://dx.doi.org/10.1002/pssa.201100801
SN  - 1862-6319
VL  - 209
IS  - 5
SP  - 900
EP  - 904
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Werner, Frederik
A1  - Spelthahn, H.
A1  - Schöning, Michael Josef
A1  - Krumbe, C.
A1  - Wagner, Torsten
A1  - Yoshinobu, T.
A1  - Keusgen, M.
T1  - Neue Ansteuerungselektronik für LAPS-basierte Biosensoren zur gleichzeitig ortsaufgelösten Messung der pH-Konzentration
JF  - Sensoren und Messsysteme 2010 [Elektronische Ressource] : Vorträge der 15. ITG/GMA-Fachtagung vom 18. bis 19. Mai 2010 in Nürnberg / Informationstechnische Gesellschaft im VDE (ITG); VDI/VDE-Gesellschaft Mess- und Automatisierungstechnik (GMA)
Y1  - 2010
SN  - 978-3-8007-3260-9
N1  - Fachtagung Sensoren und Messsysteme 15, 2010, Nürnberg ; Gesellschaft Mess- und Automatisierungstechnik
SP  - 109
EP  - 114
PB  - VDE Verlag
CY  - Berlin
ER  - 
TY  - JOUR
A1  - Yoshinobu, Tatsuo
A1  - Miyamoto, Ko-ichiro
A1  - Werner, Frederik
A1  - Poghossian, Arshak
A1  - Wagner, Torsten
A1  - Schöning, Michael Josef
T1  - Light-addressable potentiometric sensors for quantitative spatial imaging of chemical species
JF  - Annual Review of Analytical Chemistry
N2  - 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.
Y1  - 2017
U6  - http://dx.doi.org/10.1146/annurev-anchem-061516-045158
SN  - 1936-1327
VL  - 10
SP  - 225
EP  - 246
PB  - Annual Reviews
CY  - Palo Alto, Calif.
ER  - 
TY  - JOUR
A1  - Wagner, Torsten
A1  - Vornholt, Wolfgang
A1  - Werner, Frederik
A1  - Yoshinobu, Tatsuo
A1  - Miyamoto, Ko-Ichiro
A1  - Keusgen, Michael
A1  - Schöning, Michael Josef
T1  - Light-addressable potentiometric sensor (LAPS) combined with magnetic beads for pharmaceutical screening
JF  - Physics in medicine
N2  - The light-addressable potentiometric sensor (LAPS) has the unique feature to address different regions of a sensor surface without the need of complex structures. Measurements at different locations on the sensor surface can be performed in a common analyte solution, which distinctly simplifies the fluidic set-up. However, the measurement in a single analyte chamber prevents the application of different drugs or different concentrations of a drug to each measurement spot at the same time as in the case of multi-reservoir-based set-ups. In this work, the authors designed a LAPS-based set-up for cell culture screening that utilises magnetic beads loaded with the endotoxin (lipopolysaccharides, LPS), to generate a spatially distributed gradient of analyte concentration. Different external magnetic fields can be adjusted to move the magnetic beads loaded with a specific drug within the measurement cell. By recording the metabolic activities of a cell layer cultured on top of the LAPS surface, this work shows the possibility to apply different concentrations of a sample along the LAPS measurement spots within a common analyte solution.
Y1  - 2016
U6  - http://dx.doi.org/10.1016/j.phmed.2016.03.001
SN  - 2352-4510
VL  - 2016
IS  - 1
SP  - 2
EP  - 7
ER  - 
TY  - JOUR
A1  - Siqueira, Jose R.
A1  - Werner, Frederik
A1  - Bäcker, Matthias
A1  - Poghossian, Arshak
A1  - Zucolotto, Valtencir
A1  - Oliveira, Osvaldo N. Jr.
A1  - Schöning, Michael Josef
T1  - Layer-by-Layer Assembly of Carbon Nanotubes Incorporated in Light-Addressable Potentiometric Sensors
JF  - Journal of Physical Chemistry C. 113 (2009), H. 33
Y1  - 2009
SN  - 1932-7455
SP  - 14765
EP  - 14770
PB  - American Chemical Society
CY  - Washington, DC
ER  - 
TY  - JOUR
A1  - Werner, Frederik
A1  - Miyamoto, Ko-ichiro
A1  - Wagner, Torsten
A1  - Schöning, Michael Josef
A1  - Yoshinobu, Tatsuo
T1  - Lateral resolution enhancement of pulse-driven light-addressable potentiometric sensor
JF  - Sensor and Actuators B: Chemical
N2  - To study chemical and biological processes, spatially resolved determination of the concentrations of one or more analyte species is of distinct interest. With a light-addressable potentiometric sensor (LAPS), chemical images can be created, which visualize the concentration distribution above the sensor plate. One important challenge is to achieve a good lateral resolution in order to detect events that take place in a small and limited region. LAPS utilizes a focused light spot to address the measurement region. By moving this light spot along the semiconductor sensor plate, the concentration distribution can be observed. In this study, we show that utilizing a pulse as light excitation instead of a traditionally used continuously modulated light excitation, the lateral resolution can be improved by a factor of 6 or more.
KW  - Chemical images
KW  - LAPS
KW  - Light-addressable potentiometric sensor
Y1  - 2017
U6  - http://dx.doi.org/10.1016/j.snb.2017.02.057
SN  - 0925-4005
VL  - 248
SP  - 961
EP  - 965
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Wu, Chunsheng
A1  - Bronder, Thomas
A1  - Poghossian, Arshak
A1  - Werner, Frederik
A1  - Bäcker, Matthias
A1  - Schöning, Michael Josef
T1  - Label-free electrical detection of DNA with a multi-spot LAPS: First step towards light-addressable DNA chips
JF  - Physica status solidi A : Applications and materials science
N2  - A multi-spot (4 × 4 spots) light-addressable potentiometric sensor (MLAPS) consisting of an Al–p-Si–SiO2 structure has been applied for the label-free electrical detection of DNA (deoxyribonucleic acid) immobilization and hybridization by the intrinsic molecular charge for the first time. Single-stranded probe ssDNA molecules (20 bases) were covalently immobilized onto the silanized SiO2 gate surface. The unspecific adsorption of mismatch ssDNA on the MLAPS gate surface was blocked by bovine serum albumin molecules. To reduce the screening effect and to achieve a high sensor signal, the measurements were performed in a low ionic-strength solution. The photocurrent–voltage (I–V) curves were simultaneously recorded on all 16 spots after each surface functionalization step. Large shifts of I–V curves of 25 mV were registered after the DNA immobilization and hybridization event. In contrast, a small potential shift (∼5 mV) was observed in case of mismatch ssDNA, revealing good specificity of the sensor. The obtained results demonstrate the potential of the MLAPS as promising transducer platform for the multi-spot label-free electrical detection of DNA molecules by their intrinsic molecular charge.
Y1  - 2014
U6  - http://dx.doi.org/10.1002/pssa.201330442
SN  - 1521-396X (E-Journal); 1862-6319 (E-Journal); 0031-8965 (Print); 1862-6300 (Print)
VL  - 211
IS  - 6
SP  - 1423
EP  - 1428
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Wu, Chunsheng
A1  - Bronder, Thomas
A1  - Poghossian, Arshak
A1  - Werner, Frederik
A1  - Schöning, Michael Josef
T1  - Label-free detection of DNA using light-addressable potentiometric sensor modified with a positively charged polyelectrolyte layer
JF  - Nanoscale
N2  - A multi-spot (16 spots) light-addressable potentiometric sensor (MLAPS) consisting of an Al–p-Si–SiO2 structure modified with a weak polyelectrolyte layer of PAH (poly(allylamine hydrochloride)) was applied for the label-free electrical detection of DNA (deoxyribonucleic acid) immobilization and hybridization by the intrinsic molecular charge for the first time. To achieve a preferentially flat orientation of DNA strands and thus, to reduce the distance between the DNA charge and MLAPS surface, the negatively charged probe single-stranded DNAs (ssDNA) were electrostatically adsorbed onto the positively charged PAH layer using a simple layer-by-layer (LbL) technique. In this way, more DNA charge can be positioned within the Debye length, yielding a higher sensor signal. The surface potential changes in each spot induced due to the surface modification steps (PAH adsorption, probe ssDNA immobilization, hybridization with complementary target DNA (cDNA), non-specific adsorption of mismatched ssDNA) were determined from the shifts of photocurrent–voltage curves along the voltage axis. A high sensor signal of 83 mV was registered after immobilization of probe ssDNA onto the PAH layer. The hybridization signal increases from 5 mV to 32 mV with increasing the concentration of cDNA from 0.1 nM to 5 μM. In contrast, a small signal of 5 mV was recorded in the case of non-specific adsorption of fully mismatched ssDNA (5 μM). The obtained results demonstrate the potential of the MLAPS in combination with the simple and rapid LbL immobilization technique as a promising platform for the future development of multi-spot light-addressable label-free DNA chips with direct electrical readout.
Y1  - 2015
U6  - http://dx.doi.org/10.1039/C4NR07225A
VL  - 14
IS  - 7
SP  - 6143
EP  - 6150
PB  - Royal Society of Chemistry (RSC)
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Bronder, Thomas
A1  - Wu, Chunsheng
A1  - Poghossian, Arshak
A1  - Werner, Frederik
A1  - Keusgen, M.
A1  - Schöning, Michael Josef
T1  - Label-free detection of DNA hybridization with light-addressable potentiometric sensors: comparison of various DNA-immobilization strategies
JF  - Procedia Engineering
N2  - Light-addressable potentiometric sensors (LAPS) consisting of a p-Si-SiO2 and p-Si-SiO2-Au structure, respectively, have been tested for a label-free electrical detection of DNA (deoxyribonucleic acid) hybridization. Three different strategies for immobilizing single-stranded probe DNA (ssDNA) molecules on a LAPS surface have been studied and compared: (a) immobilization of thiol-modified ssDNA on the patterned Au surface via gold-thiol bond, (b) covalent immobilization of amino-modified ssDNA onto the SiO2 surface functionalized with 3-aminopropyltriethoxysilane and (c) layer-by-layer adsorption of negatively charged ssDNA on a positively charged weak polyelectrolyte layer of poly(allylamine hydrochloride).
KW  - LAPS
KW  - lable-free detection
KW  - DNA hybridization
KW  - field-effect sensor
Y1  - 2014
U6  - http://dx.doi.org/10.1016/j.proeng.2014.11.647
SN  - 1877-7058
N1  - EUROSENSORS 2014 ; European Conference on Solid-State Transducers <28, 2014>
VL  - 87
SP  - 755
EP  - 758
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - CHAP
A1  - Werner, Frederik
A1  - Mansour, Ahmed
A1  - Rateike, Franz-Matthias
A1  - Schusser, Sebastian
A1  - Wagner, Torsten
A1  - Yoshinobu, Tatsuo
A1  - Keusgen, Michael
A1  - Schöning, Michael Josef
ED  - Gerlach, Gerald
T1  - Kompakter Aufbau eines lichtadressierbaren potentiometrischen Sensors mit verfahrbarem Diodenlaser
T2  - 10. Dresdner Sensor-Symposium : Dresden, 5. - 7. Dezember 2011 ; miniaturisierte analytische Verfahren, Hochtemperatur-Sensoren, Sensoren für Bioprozess- und Verfahrenstechnik, Sensoren für die Medizin, Chemische Verfahrenstechnik, Lebensmittelanalytik, innovative Sensorlösungen, Sensoren für die Wasserqualität, Selbstüberwachung / Gerald Gerlach ... (Hg.) Dresdner Beiträge zur Sensorik. 43
Y1  - 2011
SN  - 978-3-942710-53-4
SP  - 277
EP  - 280
PB  - TUDpress
CY  - Dresden
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  - Werner, Frederik
A1  - Wagner, Torsten
A1  - Miyamoto, Ko-ichiro
A1  - Yoshinobu, Tatsuo
A1  - Schöning, Michael Josef
T1  - High speed and high resolution chemical imaging based on a new type of OLED-LAPS set-up
JF  - Sensors and Actuators B: Chemical
N2  - Light-addressable potentiometric sensors (LAPS) are field-effect-based sensors. A modulated light source is used to define the particular measurement spot to perform spatially resolved measurements of chemical species and to generate chemical images. In this work, an organic-LED (OLED) display has been chosen as a light source. This allows high measurement resolution and miniaturisation of the system. A new developed driving method for the OLED display optimised for LAPS-based measurements is demonstrated. The new method enables to define modulation frequencies between 1 kHz and 16 kHz and hence, reduces the measurement time of a chemical image by a factor of 40 compared to the traditional addressing of an OLED display.
Y1  - 2012
U6  - http://dx.doi.org/10.1016/j.snb.2011.12.102
SN  - 0925-4005
N1  - Part of special issue "Selected Papers presented at Eurosensors XXV"
VL  - 175
SP  - 118
EP  - 122
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Werner, Frederik
A1  - Wagner, Torsten
A1  - Miyamoto, Ko-ichiro
A1  - Yoshinobu, Tatsuo
A1  - Schöning, Michael Josef
T1  - High speed and high resolution chemical imaging based on a new type of OLED-LAPS set-up
JF  - Procedia Engineering. 25 (2011)
Y1  - 2011
SN  - 1877-7058
N1  - EurosensorsXXV ; Proc. Eurosensors XXV, September 4-7, 2011, Athens, Greece
SP  - 346
EP  - 349
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Werner, Frederik
A1  - Wagner, Torsten
A1  - Yoshinobu, Tatsuo
A1  - Keusgen, Michael
A1  - Schöning, Michael Josef
T1  - Frequency behaviour of light-addressable potentiometric sensors
JF  - Physica Status Solidi (A)
N2  - Light-addressable potentiometric sensors (LAPS) are semiconductor-based potentiometric sensors, with the advantage to detect the concentration of a chemical species in a liquid solution above the sensor surface in a spatially resolved manner. The addressing is achieved by a modulated and focused light source illuminating the semiconductor and generating a concentration-depending photocurrent. This work introduces a LAPS set-up that is able to monitor the electrical impedance in addition to the photocurrent. The impedance spectra of a LAPS structure, with and without illumination, as well as the frequency behaviour of the LAPS measurement are investigated. The measurements are supported by electrical equivalent circuits to explain the impedance and the LAPS-frequency behaviour. The work investigates the influence of different parameters on the frequency behaviour of the LAPS. Furthermore, the phase shift of the photocurrent, the influence of the surface potential as well as the changes of the sensor impedance will be discussed.
Y1  - 2013
U6  - http://dx.doi.org/10.1002/pssa.201200929
SN  - 1521-396X ; 0031-8965
VL  - 210
IS  - 5
SP  - 884
EP  - 891
PB  - Wiley-VCH
CY  - Weinheim
ER  -