TY - JOUR A1 - Takenaga, Shoko A1 - Biselli, Manfred A1 - Schnitzler, Thomas A1 - Öhlschläger, Peter A1 - Wagner, Torsten A1 - Schöning, Michael Josef T1 - Toward multi-analyte bioarray sensors: LAPS-based on-chip determination of a Michaelis–Menten-like kinetics for cell culturing JF - Physica status solidi A : Applications and materials science N2 - The metabolic activity of Chinese hamster ovary (CHO) cells was observed using a light-addressable potentiometric sensor (LAPS). The dependency toward different glucose concentrations (17–200 mM) follows a Michaelis–Menten kinetics trajectory with Kₘ = 32.8 mM, and the obtained Kₘ value in this experiment was compared with that found in literature. In addition, the pH shift induced by glucose metabolism of tumor cells transfected with the HPV-16 genome (C3 cells) was successfully observed. These results indicate the possibility to determine the tumor cells metabolism with a LAPS-based measurement device. Y1 - 2014 U6 - http://dx.doi.org/10.1002/pssa.201330464 SN - 1521-396X (E); 1862-6319 (E-Journal); 0031-8965 (Print); 1862-6300 (Print) VL - 211 IS - 6 SP - 1410 EP - 1415 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Guo, Yuanyuan A1 - Seki, Kosuke A1 - Miyamoto, Ko-ichiro A1 - Wagner, Torsten A1 - Schöning, Michael Josef A1 - Yoshinobu, Tatsuo T1 - Novel photoexcitation method for light-addressable potentiometric sensor with higher spatial resolution JF - Applied physics express : APEX N2 - A novel photoexcitation method for the light-addressable potentiometric sensor (LAPS) is proposed to achieve a higher spatial resolution of chemical images. The proposed method employs a combined light source that consists of a modulated light probe, which generates the alternating photocurrent signal, and a ring of constant illumination surrounding it. The constant illumination generates a sheath of carriers with increased concentration which suppresses the spread of photocarriers by enhanced recombination. A device simulation was carried out to verify the effect of constant illumination on the spatial resolution, which demonstrated that a higher spatial resolution can be obtained. Y1 - 2014 U6 - http://dx.doi.org/10.7567/APEX.7.067301 SN - 1882-0786 (E-Journa); 1882-0778 (Print) VL - 7 IS - 6 SP - 067301-4 PB - IOP CY - Bristol ER - TY - JOUR A1 - Guo, Yuanyuan A1 - Miyamoto, Ko-ichiro A1 - Wagner, Torsten A1 - Schöning, Michael Josef A1 - Yoshinobu, Tatsuo T1 - Theoretical study and simulation of light-addressable potentiometric sensors JF - Physica status solidi (A) : applications and materials N2 - The light-addressable potentiometric sensor (LAPS) is a semiconductor-based potentiometric sensor using a light probe with an ability of detecting the concentration of biochemical species in a spatially resolved manner. As an important biomedical sensor, research has been conducted to improve its performance, for instance, to realize high-speed measurement. In this work, the idea of facilitating the device-level simulation, instead of using an equivalent-circuit model, is presented for detailed analysis and optimization of the performance of the LAPS. Both carrier distribution and photocurrent response have been simulated to provide new insight into both amplitude-mode and phase-mode operations of the LAPS. Various device parameters can be examined to effectively design and optimize the LAPS structures and setups for enhanced performance. Y1 - 2014 U6 - http://dx.doi.org/10.1002/pssa.201330354 SN - 0031-8965 VL - 211 IS - 6 SP - 1467 EP - 1472 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Guo, Yuanyuan A1 - Miyamoto, Ko-ichiro A1 - Wagner, Torsten A1 - Schöning, Michael Josef A1 - Yoshinobu, Tatsuo T1 - Device simulation of the light-addressable potentiometric sensor for the investigation of the spatial resolution JF - Sensors and actuators B: Chemical N2 - As a semiconductor-based electrochemical sensor, the light-addressable potentiometric sensor (LAPS) can realize two dimensional visualization of (bio-)chemical reactions at the sensor surface addressed by localized illumination. Thanks to this imaging capability, various applications in biochemical and biomedical fields are expected, for which the spatial resolution is critically significant. In this study, therefore, the spatial resolution of the LAPS was investigated in detail based on the device simulation. By calculating the spatiotemporal change of the distributions of electrons and holes inside the semiconductor layer in response to a modulated illumination, the photocurrent response as well as the spatial resolution was obtained as a function of various parameters such as the thickness of the Si substrate, the doping concentration, the wavelength and the intensity of illumination. The simulation results verified that both thinning the semiconductor substrate and increasing the doping concentration could improve the spatial resolution, which were in good agreement with known experimental results and theoretical analysis. More importantly, new findings of interests were also obtained. As for the dependence on the wavelength of illumination, it was found that the known dependence was not always the case. When the Si substrate was thick, a longer wavelength resulted in a higher spatial resolution which was known by experiments. When the Si substrate was thin, however, a longer wavelength of light resulted in a lower spatial resolution. This finding was explained as an effect of raised concentration of carriers, which reduced the thickness of the space charge region. The device simulation was found to be helpful to understand the relationship between the spatial resolution and device parameters, to understand the physics behind it, and to optimize the device structure and measurement conditions for realizing higher performance of chemical imaging systems. Y1 - 2014 U6 - http://dx.doi.org/10.1016/j.snb.2014.08.016 SN - 1873-3077 (E-Journal); 0925-4005 (Print) VL - 204 SP - 659 EP - 665 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Guo, Yuanyuan A1 - Seki, Kosuke A1 - Miyamoto, Ko-ichiro A1 - Wagner, Torsten A1 - Schöning, Michael Josef A1 - Yoshinobu, Tatsuo T1 - Device simulation of the light-addressable potentiometric sensor with a novel photoexcitation method for a higher spatial resolution JF - Procedia Engineering N2 - A novel photoexcitation method for the light-addressable potentiometric sensor (LAPS) realized a higher spatial resolution of chemical imaging. In this method, a modulated light probe, which generates the alternating photocurrent signal, is surrounded by a ring of constant light, which suppresses the lateral diffusion of photocarriers by enhancing recombination. A device simulation verified that a higher spatial resolution could be obtained by adjusting the gap between the modulated and constant light. It was also found that a higher intensity and a longer wavelength of constant light was more effective. However, there exists a tradeoff between the spatial resolution and the amplitude of the photocurrent, and thus, the signal-to-noise ratio. A tilted incidence of constant light was applied, which could achieve even higher resolution with a smaller loss of photocurrent. KW - Light-addressable Potentiometric Sensor KW - novel photoexcitation method KW - tilted constant illumination KW - spatial resolution Y1 - 2014 U6 - http://dx.doi.org/10.1016/j.proeng.2014.11.369 SN - 1877-7058 N1 - EUROSENSORS 2014 ; European Conference on Solid-State Transducers <28, 2014> VL - 87 SP - 456 EP - 459 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Miyamoto, K. A1 - Seki, K. A1 - Wagner, Torsten A1 - Schöning, Michael Josef A1 - Yoshinobu, T. T1 - Enhancement of the spatial resolution of the chemical imaging sensor by a hybrid fiber-optic illumination JF - Procedia Engineering N2 - The chemical imaging sensor, which is based on the principle of the light-addressable potentiometric sensor (LAPS), is a powerful tool to visualize the spatial distribution of chemical species on the sensor surface. The spatial resolution of this sensor depends on the diffusion of photocarriers excited by a modulated light. In this study, a novel hybrid fiber-optic illumination was developed to enhance the spatial resolution. It consists of a modulated light probe to generate a photocurrent signal and a ring of constant light, which suppresses the lateral diffusion of minority carriers excited by the modulated light. It is demonstrated that the spatial resolution was improved from 92 μm to 68 μm. Y1 - 2014 U6 - http://dx.doi.org/10.1016/j.proeng.2014.11.563 SN - 1877-7058 N1 - EUROSENSORS 2014 ; European Conference on Solid-State Transducers <28, 2014> VL - 87 SP - 612 EP - 615 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Miyamoto, Ko-ichiro A1 - Hirayama, Yuji A1 - Wagner, Torsten A1 - Schöning, Michael Josef A1 - Yoshinobu, Tatsuo T1 - Visualization of enzymatic reaction in a microfluidic channel using chemical imaging sensor JF - Electrochimica acta Y1 - 2013 SN - 1873-3859 (E-Journal); 0013-4686 (Print) SP - Publ. online PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Itabashi, Akinori A1 - Kosaka, Naoki A1 - Miyamoto, Ko-ichiro A1 - Wagner, Torsten A1 - Schöning, Michael Josef T1 - High-speed chemical imaging system based on front-side-illuminated LAPS JF - Sensors and actuators B: Chemical N2 - The chemical imaging sensor is a semiconductor-based chemical sensor that can visualize the spatial distribution of specific ions on the sensing surface. The conventional chemical imaging system based on the light-addressable potentiometric sensor (LAPS), however, required a long time to obtain a chemical image, due to the slow mechanical scan of a single light beam. For high-speed imaging, a plurality of light beams modulated at different frequencies can be employed to measure the ion concentrations simultaneously at different locations on the sensor plate by frequency division multiplex (FDM). However, the conventional measurement geometry of back-side illumination limited the bandwidth of the modulation frequency required for FDM measurement, because of the low-pass filtering characteristics of carrier diffusion in the Si substrate. In this study, a high-speed chemical imaging system based on front-side-illuminated LAPS was developed, which achieved high-speed spatiotemporal recording of pH change at a rate of 70 frames per second. Y1 - 2013 U6 - http://dx.doi.org/10.1016/j.snb.2013.03.016 SN - 1873-3077 VL - 182 SP - 315 EP - 321 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 - TY - JOUR A1 - Miyamoto, Ko-ichiro A1 - Ichimura, Hiroki A1 - Wagner, Torsten A1 - Schöning, Michael Josef A1 - Yoshinobu, Tatsuo T1 - Chemical imaging of the concentration profile of ion diffusion in a microfluidic channel JF - Sensors and actuators. B: Chemical N2 - The chemical imaging sensor is a device to visualize the spatial distribution of chemical species based on the principle of LAPS (light-addressable potentiometric sensor), which is a field-effect chemical sensor based on semiconductor. In this study, the chemical imaging sensor has been applied to investigate the ion profile of laminar flows in a microfluidic channel. The chemical images (pH maps) were collected in a Y-shaped microfluidic channel while injecting HCl and NaCl solutions into two branches. From the chemical images, it was clearly observed that the injected solutions formed laminar flows in the channel. In addition, ion diffusion across the laminar flows was observed, and the diffusion coefficient could be derived by fitting the pH profiles to the Fick's equation. Y1 - 2013 U6 - http://dx.doi.org/10.1016/j.snb.2013.04.057 SN - 1873-3077 (E-Journal); 0925-4005 (Print) N1 - Part of special issue "Selected Papers from the 26th European Conference on Solid-State Transducers" VL - 189 SP - 240 EP - 245 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 - Wagner, Torsten A1 - Werner, Frederik A1 - Miyamoto, Ko-Ichiro A1 - Schöning, Michael Josef A1 - Yoshinobu, Tatsuo T1 - Development and characterisation of a compact light-addressable potentiometric sensor (LAPS) based on the digital light processing (DLP) technology for flexible chemical imaging JF - Sensors and Actuators B: Chemical N2 - Chemical imaging systems allow the visualisation of the distribution of chemical species on the sensor surface. This work represents a new flexible approach to read out light-addressable potentiometric sensors (LAPS) with the help of a digital light processing (DLP) set-up. The DLP, known well for video projectors, consists of a mirror-array MEMS device, which allows fast and flexible generation of light patterns. With the help of these light patterns, the sensor surface of the LAPS device can be addressed. The DLP approach has several advantages compared to conventional LAPS set-ups, e.g., the spot size and the shape of the light pointer can be changed easily and no mechanical movement is necessary, which reduces the size of the set-up and increases the stability and speed of the measurement. In addition, the modulation frequency and intensity of the light beam are important parameters of the LAPS set-up. Within this work, the authors will discuss two different ways of light modulation by the DLP set-up, investigate the influence of different modulation frequencies and different light intensities as well as demonstrate the scanning capabilities of the new set-up by pH mapping on the sensor surface. Y1 - 2012 U6 - http://dx.doi.org/10.1016/j.snb.2010.12.003 SN - 0925-4005 N1 - Part of special issue "Eurosensors XXIV, 2010" VL - 170 SP - 34 EP - 39 PB - Elsevier CY - Amsterdam 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 - Miyamoto, Ko-ichiro A1 - Kaneko, Kazumi A1 - Matsuo, Akira A1 - Wagner, Torsten A1 - Kanoh, Shiníchiro A1 - Schöning, Michael Josef A1 - Yoshinobu, Tatsuo T1 - Miniaturized chemical imaging sensor system using an OLED display panel JF - Sensors and Actuators B: Chemical N2 - The chemical imaging sensor is a semiconductor-based chemical sensor that can visualize the two-dimensional distribution of specific ions or molecules in the solution. In this study, we developed a miniaturized chemical imaging sensor system with an OLED display panel as a light source that scans the sensor plate. In the proposed configuration, the display panel is placed directly below the sensor plate and illuminates the back surface. The measured area defined by illumination can be arbitrarily customized to fit the size and the shape of the sample to be measured. The waveform of the generated photocurrent, the current–voltage characteristics and the pH sensitivity were investigated and pH imaging with this miniaturized system was demonstrated. KW - LAPS KW - Light-addressable potentiometric sensor KW - Chemical imaging sensor KW - Organic light-emitting diode display Y1 - 2012 U6 - http://dx.doi.org/10.1016/j.snb.2011.02.029 SN - 0925-4005 N1 - Part of special issue "Eurosensors XXIV, 2010" VL - 170 SP - 82 EP - 87 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Miyamoto, K. A1 - Ichimura, H. A1 - Wagner, Torsten A1 - Yoshinobu, T. A1 - Schöning, Michael Josef T1 - Chemical Imaging of ion Diffusion in a Microfluidic Channel JF - Procedia Engineering N2 - The chemical imaging sensor is a chemical sensor which is capable of visualizing the spatial distribution of chemical species in sample solution. In this study, a novel measurement system based on the chemical imaging sensor was developed to observe the inside of a Y-shaped microfluidic channel while injecting two sample solutions from two branches. From the collected chemical images, it was clearly observed that the injected solutions formed laminar flows in the microfluidic channel. In addition, ion diffusion across the laminar flows was observed. This label-free method can acquire quantitative data of ion distribution and diffusion in microfluidic devices, which can be used to determine the diffusion coefficients, and therefore, the molecular weights of chemical species in the sample solution. Y1 - 2012 U6 - http://dx.doi.org/10.1016/j.proeng.2012.09.289 SN - 1877-7058 N1 - Part of special issue "26th European Conference on Solid-State Transducers, EUROSENSOR 2012" IS - 47 SP - 886 EP - 889 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Wagner, Torsten A1 - Shigiahara, N. A1 - Miyamoto, K. A1 - Suzurikawa, J. A1 - Finger, F. A1 - Schöning, Michael Josef A1 - Yoshinobu, T. T1 - Light-addressable Potentiometric Sensors and Light–addressable Electrodes as a Combined Sensor-and-manipulator Microsystem with High Flexibility JF - Procedia Engineering N2 - This work describes the novel combination of the light-addressable electrode (LAE) and the light-addressable potentiometric sensor (LAPS) into a microsystem set-up. Both the LAE as well as the LAPS shares the principle of addressing the active spot by means of a light beam. This enables both systems to manipulate resp. to detect an analyte with a high spatial resolution. Hence, combining both principles into a single set-up enables the active stimulation e.g., by means of electrolysis and a simultaneous observation e.g., the response of an entrapped biological cell by detection of extracellular pH changes. The work will describe the principles of both technologies and the necessary steps to integrate them into a single set-up. Furthermore, examples of application and operation of such systems will be presented. Y1 - 2012 U6 - http://dx.doi.org/10.1016/j.proeng.2012.09.290 SN - 1877-7058 N1 - Part of special issue "26th European Conference on Solid-State Transducers, EUROSENSOR 2012" IS - 47 SP - 890 EP - 893 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Werner, Frederik A1 - Schusser, Sebastian A1 - Spalthahn, Heiko A1 - Wagner, Torsten A1 - Yoshinobu, Tatsuo A1 - Schöning, Michael Josef T1 - Field-programmable gate array based controller for multi spot light-addressable potentiometric sensors with integrated signal correction mode JF - Electrochimica Acta N2 - 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. Y1 - 2011 U6 - http://dx.doi.org/10.1016/j.electacta.2011.03.012 SN - 0013-4686 VL - 56 IS - 26 SP - 9656 EP - 9660 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Miyamoto, Ko-ichiro A1 - Wagner, Torsten A1 - Yoshinobu, Tatsuo A1 - Kanoh, Shin`ichiro A1 - Schöning, Michael Josef T1 - Phase-mode LAPS and its application to chemical imaging JF - Sensors and Actuators B: Chemical. 154 (2011), H. 1 Y1 - 2011 SN - 1873-3077 SP - 28 EP - 32 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Miyamoto, Ko-ichiro A1 - Yoshida, Midori A1 - Sakai, Taito A1 - Matsuzaka, Atsushi A1 - Wagner, Torsten A1 - Kanoh, Sanoh A1 - Yoshinobu, Tatsuo A1 - Schöning, Michael Josef T1 - Differential setup of light-addressable potentiometric sensor with an enzyme reactor in a flow channel JF - Japanese Journal of Applied Physics. 50 (2011) Y1 - 2011 SN - 0021-4922 SP - 04DL08-1 EP - 04DL08-5 PB - Japan Society of Applied Physics CY - Bristol ER - TY - JOUR A1 - Miyamoto, Ko-ichiro A1 - Wagner, Torsten A1 - Yoshinobu, Tatsuo A1 - Kanoh, Shin`ichiro A1 - Schöning, Michael Josef T1 - Phase-mode operation of FDM-LAPS JF - Sensor letters Y1 - 2011 SN - 1546-1971 VL - 9 IS - 2 SP - 691 EP - 694 PB - American Scientific Publishers CY - Stevenson Ranch, Calif. ER -