International Symposium on LifeChips 2006

Two dimensional dynamic pH image sensor based on a CCD technique
The demand for biosensors has increased in various fields of application, such as in biochemistry and medical diagnosis. pH sensors are one of the more important types of biosensor, and various types of pH sensor have been developed. Conventionally, for a solution with a uniform concentration, the average value of pH is measured. The most well-known semiconductor based pH sensor is the ISFET (Ion Sensitive field-effect transistor). If the distribution of chemical phenomena can be obtained as a visible image in real time, the local variations in these will lead to a better understanding of these phenomena. These imaging systems will enable us to extend the scope of chemical measurements. We present a pH image sensor, which is capable of measuring two-dimensional (2-D) distributions of various chemical reactions in real time. The novel pH CMOS imaging sensors developed in this work use a charge transfer technique and with them it is possible to form images of variations in chemical reactions. Prototype pH CMOS image sensors were successfully fabricated using CMOS (Complimentary Metal-oxide Semiconductor) circuit process technology and were used to measure two-dimensional distributions of various chemical reactions in moving images at 30 frames per sec. It is expected that this sensor can be used for novel applications such as in the medical and biochemistry fields.

Biography
Kazuaki Sawada was born in Kumamoto, Japan in 1963. He received his B.A. and M.S. degrees in electrical and electronic engineering in 1986, 1988, respectively, and he received a Ph.D. degree in system and information engineering in 1991, all from Toyohashi University of Technology, Aichi, Japan. From 1991 to 1998, he was a Research Associate in the Research Institute of Electronics, Shizuoka University, Shizuoka, Japan. Since 1998, he joined the Department of Electrical and Electronic Engineering, Toyohashi University of Technology, where he is now serving as an Assistant Professor. He was a guest professor of Technical University of Munich in 2005. His current research interests focus on the development of ultrahigh-sensitive bio-sensing devices and micro-fluidic devices.