ABSTRACT
This chapter introduces recent advancement of complementary metal–oxide–semiconductor (CMOS) image sensors. It mentions in detail the fundamental operation principle as well as some recent topics including shrinking pixel pitch, high sensitivity, high speed, and so on. The chapter demonstrates biomedical applications with CMOS image sensor technology such as retinal prosthesis, fluorescence detection for enzyme-linked immunoassay, and implantable micro imaging devices. CMOS image sensor consists of an array of pixels. Each pixel has a photodiode, a buffer and some switches, and it is interfaced with the column and row lines. Also, recently another technology, called the stacked pixel, is developed. In this case, the CMOS image sensor and some logic cells are stacked for three dimensional integration. At present, the image sensor is normally used to measure the light intensity. One can expand their usage in another dimension, like distance measurement, pH measurement and polarization.
