We propose a pixel construction for a pH image sensor with a new measurement method that spills charge to a potential wall under sensing area. The sensor pixel with 3 transistors has advantages for fabricating the sensor array with high spatial resolution compared with a conventional ISFET type sensor array using 4 transistors. The pixel size of the fabrication using the 3 transistor structure is 2 µm × 2 µm.
The line sensor was fabrication in 256 pixels. The sensor was fabricated in 4 metal 0.34 µm CMOS process. The sensor has a distinguishable spatial resolution for cells individually, because the sensor is expected to effectiveness at observation of the neuronal networks.