A novel low-noise measurement principle for LAPS and its application to faster measurement of pH

A novel measurement principle for the light-addressable potentiometric sensor (LAPS) system is proposed in this paper. With several features like low-noise and low-background, this measurement scheme extends the application of LAPS in faster high-sensitive direct monitoring of ionic concentration an...

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Bibliographic Details
Published in:Sensors and actuators. B, Chemical Chemical, 2001-04, Vol.74 (1), p.112-116
Main Authors: Md. Ismail, Abu Bakar, Sugihara, Hirokazu, Yoshinobu, Tatsuo, Iwasaki, Hiroshi
Format: Article
Language:English
Subjects:
Chemical sensor
Differential measurement
Light-addressable potentiometric sensor (LAPS)
pH sensor
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Summary:A novel measurement principle for the light-addressable potentiometric sensor (LAPS) system is proposed in this paper. With several features like low-noise and low-background, this measurement scheme extends the application of LAPS in faster high-sensitive direct monitoring of ionic concentration and small change in the surface potential without the need of costly instruments like potentiostat, lock-in amplifier. Using two out-of-phase modulated light sources applied at two different points of the Si surface of the heterostructure, a kind of differential LAPS response is obtained. Due to the addition of the two out-of-phase photocurrents, low-frequency components associated with the photocurrents are canceled out and a low-noise and hence highly sensitive response is expected. As an application of the new principle, the pH measurement of an electrolyte solution is investigated and a new instrumentation for the direct, high-sensitive, and faster measurement of pH is proposed.
ISSN:0925-4005
1873-3077
DOI:10.1016/S0925-4005(00)00719-X