TY  - JOUR
A1  - Miyamoto, Ko-ichiro
A1  - Wagner, Torsten
A1  - Mimura, Shuhei
A1  - Kanoh, Shiníchiro
A1  - Yoshinobu, Tatsuo
A1  - Schöning, Michael Josef
T1  - Constant-phase-mode operation of the light-addressable potentiometric sensor
JF  - Sensors and Actuators B: Chemical. 154 (2011), H. 2
Y1  - 2011
SN  - 1873-3077
N1  - EUROSENSORS XXIII
SP  - 119
EP  - 123
PB  - Elsevier
CY  - Amsterdam
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  - Miyamoto, Ko-ichiro
A1  - Hayashi, Kosuke
A1  - Sakamoto, Azuma
A1  - Werner, Frederik
A1  - Wagner, Torsten
A1  - Schöning, Michael Josef
A1  - Yoshinobu, Tatsuo
T1  - A high-Q resonance-mode measurement of EIS capacitive sensor by elimination of series resistance
JF  - Sensor and Actuators B: Chemical
N2  - 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.
KW  - Negative impedance convertor
KW  - Resonance-mode measurement
KW  - Chemical sensor
KW  - EIS capacitive sensor
Y1  - 2017
U6  - http://dx.doi.org/10.1016/j.snb.2017.03.002
SN  - 0925-4005
VL  - 248
SP  - 1006
EP  - 1010
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  - A high-density multi-point LAPS set-up using a VCSEL array and FPGA control
JF  - Sensors and Actuators B: Chemical. 154 (2011), H. 2
Y1  - 2011
SN  - 1873-3077
N1  - EUROSENSORS XXIII
SP  - 124
EP  - 128
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - CHAP
A1  - Yoshinobu, Tatsuo
A1  - Krause, Steffi
A1  - Miyamoto, Ko-ichiro
A1  - Werner, Frederik
A1  - Poghossian, Arshak
A1  - Wagner, Torsten
A1  - Schöning, Michael Josef
T1  - (Bio-)chemical Sensing and Imaging by LAPS and SPIM
T2  - Label-free biosensing: advanced materials, devices and applications
N2  - The light-addressable potentiometric sensor (LAPS) and scanning photo-induced impedance microscopy (SPIM) are two closely related methods to visualise the distributions of chemical species and impedance, respectively, at the interface between the sensing surface and the sample solution. They both have the same field-effect structure based on a semiconductor, which allows spatially resolved and label-free measurement of chemical species and impedance in the form of a photocurrent signal generated by a scanning light beam. In this article, the principles and various operation modes of LAPS and SPIM, functionalisation of the sensing surface for measuring various species, LAPS-based chemical imaging and high-resolution sensors based on silicon-on-sapphire substrates are described and discussed, focusing on their technical details and prospective applications.
KW  - Chemical imaging
KW  - Field-effect device
KW  - Light-addressable potentiometric sensor
KW  - Potentiometry
Y1  - 2018
SN  - 978-3-319-75219-8
SP  - 103
EP  - 132
PB  - Springer
CY  - Cham
ER  -