@article{MiyamotoItabashiWagneretal.2014, author = {Miyamoto, Ko-ichiro and Itabashi, Akinori and Wagner, Torsten and Sch{\"o}ning, Michael Josef and Yoshinobu, Tatsuo}, title = {High-speed chemical imaging inside a microfluidic channel}, series = {Sensors and actuators. B: Chemical}, volume = {194}, journal = {Sensors and actuators. B: Chemical}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1873-3077 (E-Journal); 0925-4005 (Print)}, doi = {10.1016/j.snb.2013.12.090}, pages = {521 -- 527}, year = {2014}, abstract = {In this study, a high-speed chemical imaging system was developed for visualization of the interior of a microfluidic channel. A microfluidic channel was constructed on the sensor surface of the light-addressable potentiometric sensor (LAPS), on which the ion concentrations could be measured in parallel at up to 64 points illuminated by optical fibers. The temporal change of pH distribution inside the microfluidic channel was recorded at a maximum rate of 100 frames per second (fps). The high frame rate allowed visualization of moving interfaces and plugs in the channel even at a flow velocity of 111 mm/s, which suggests the feasibility of plug-based microfluidic devices for flow-injection analysis (FIA).}, language = {en} } @article{WernerWagnerMiyamotoetal.2012, author = {Werner, Frederik and Wagner, Torsten and Miyamoto, Ko-ichiro and Yoshinobu, Tatsuo and Sch{\"o}ning, Michael Josef}, title = {High speed and high resolution chemical imaging based on a new type of OLED-LAPS set-up}, series = {Sensors and Actuators B: Chemical}, volume = {175}, journal = {Sensors and Actuators B: Chemical}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0925-4005}, doi = {10.1016/j.snb.2011.12.102}, pages = {118 -- 122}, year = {2012}, abstract = {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.}, language = {en} } @article{WernerWagnerMiyamotoetal.2011, author = {Werner, Frederik and Wagner, Torsten and Miyamoto, Ko-ichiro and Yoshinobu, Tatsuo and Sch{\"o}ning, Michael Josef}, title = {High speed and high resolution chemical imaging based on a new type of OLED-LAPS set-up}, series = {Procedia Engineering. 25 (2011)}, journal = {Procedia Engineering. 25 (2011)}, publisher = {Elsevier}, address = {Amsterdam}, isbn = {1877-7058}, pages = {346 -- 349}, year = {2011}, language = {en} } @article{WagnerMolinaYoshinobuetal.2007, author = {Wagner, Torsten and Molina, Roberto and Yoshinobu, Tatsuo and Kloock, Joachim P. and Biselli, Manfred and Canzoneri, Michele and Schnitzler, Thomas and Sch{\"o}ning, Michael Josef}, title = {Handheld multi-channel LAPS device as a transducer platform for possible biological and chemical multi-sensor applications}, series = {Electrochimica Acta. 53 (2007), H. 2}, journal = {Electrochimica Acta. 53 (2007), H. 2}, isbn = {0013-4686}, pages = {305 -- 311}, year = {2007}, language = {en} } @article{WernerWagnerYoshinobuetal.2013, author = {Werner, Frederik and Wagner, Torsten and Yoshinobu, Tatsuo and Keusgen, Michael and Sch{\"o}ning, Michael Josef}, title = {Frequency behaviour of light-addressable potentiometric sensors}, series = {Physica Status Solidi (A)}, volume = {210}, journal = {Physica Status Solidi (A)}, number = {5}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1521-396X ; 0031-8965}, doi = {10.1002/pssa.201200929}, pages = {884 -- 891}, year = {2013}, abstract = {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.}, language = {en} } @article{WagnerWernerMiyamotoetal.2010, author = {Wagner, Torsten and Werner, Frederik and Miyamoto, Ko-ichiro and Ackermann, Hans-Josef and Yoshinobu, Tatsuo and Sch{\"o}ning, Michael Josef}, title = {FPGA-based LAPS device for the flexible design of sensing sites on functional interfaces}, series = {Physica Status Solidi (A). 207 (2010), H. 4}, journal = {Physica Status Solidi (A). 207 (2010), H. 4}, isbn = {1862-6300}, pages = {844 -- 849}, year = {2010}, language = {en} } @article{PoghossianYoshinobuSchoening2003, author = {Poghossian, Arshak and Yoshinobu, Tatsuo and Sch{\"o}ning, Michael Josef}, title = {Flow-velocity microsensors based on semiconductor field-effect structures}, series = {Sensors. 3 (2003), H. 7}, journal = {Sensors. 3 (2003), H. 7}, isbn = {1424-8220}, pages = {202 -- 212}, year = {2003}, language = {en} } @article{WernerSchusserSpalthahnetal.2011, author = {Werner, Frederik and Schusser, Sebastian and Spalthahn, Heiko and Wagner, Torsten and Yoshinobu, Tatsuo and Sch{\"o}ning, Michael Josef}, title = {Field-programmable gate array based controller for multi spot light-addressable potentiometric sensors with integrated signal correction mode}, series = {Electrochimica Acta}, volume = {56}, journal = {Electrochimica Acta}, number = {26}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0013-4686}, doi = {10.1016/j.electacta.2011.03.012}, pages = {9656 -- 9660}, year = {2011}, abstract = {A light-addressable potentiometric sensor (LAPS) can measure the concentration of one or several analytes at the sensor surface simultaneously in a spatially resolved manner. A modulated light pointer stimulates the semiconductor structure at the area of interest and a responding photocurrent can be read out. By simultaneous stimulation of several areas with light pointers of different modulation frequencies, the read out can be performed at the same time. With the new proposed controller electronic based on a field-programmable gate array (FPGA), it is possible to control the modulation frequencies, phase shifts, and light brightness of multiple light pointers independently and simultaneously. Thus, it is possible to investigate the frequency response of the sensor, and to examine the analyte concentration by the determination of the surface potential with the help of current/voltage curves and phase/voltage curves. Additionally, the ability to individually change the light intensities of each light pointer is used to perform signal correction.}, language = {en} } @article{YoshinobuMiyamotoWagneretal.2024, author = {Yoshinobu, Tatsuo and Miyamoto, Ko-ichiro and Wagner, Torsten and Sch{\"o}ning, Michael Josef}, title = {Field-effect sensors combined with the scanned light pulse technique: from artificial olfactory images to chemical imaging technologies}, series = {Chemosensors}, volume = {12}, journal = {Chemosensors}, number = {2}, publisher = {MDPI}, address = {Basel}, issn = {2227-9040}, doi = {10.3390/chemosensors12020020}, pages = {Artikel 20}, year = {2024}, abstract = {The artificial olfactory image was proposed by Lundstr{\"o}m et al. in 1991 as a new strategy for an electronic nose system which generated a two-dimensional mapping to be interpreted as a fingerprint of the detected gas species. The potential distribution generated by the catalytic metals integrated into a semiconductor field-effect structure was read as a photocurrent signal generated by scanning light pulses. The impact of the proposed technology spread beyond gas sensing, inspiring the development of various imaging modalities based on the light addressing of field-effect structures to obtain spatial maps of pH distribution, ions, molecules, and impedance, and these modalities have been applied in both biological and non-biological systems. These light-addressing technologies have been further developed to realize the position control of a faradaic current on the electrode surface for localized electrochemical reactions and amperometric measurements, as well as the actuation of liquids in microfluidic devices.}, language = {en} } @article{MiyamotoYoshidaSakaietal.2011, author = {Miyamoto, Ko-ichiro and Yoshida, Midori and Sakai, Taito and Matsuzaka, Atsushi and Wagner, Torsten and Kanoh, Sanoh and Yoshinobu, Tatsuo and Sch{\"o}ning, Michael Josef}, title = {Differential setup of light-addressable potentiometric sensor with an enzyme reactor in a flow channel}, series = {Japanese Journal of Applied Physics. 50 (2011)}, journal = {Japanese Journal of Applied Physics. 50 (2011)}, publisher = {Japan Society of Applied Physics}, address = {Bristol}, isbn = {0021-4922}, pages = {04DL08-1 -- 04DL08-5}, year = {2011}, language = {en} }