CMOS photodetectors and imaging systems for biomedical applications

In this paper, we discuss in detail photodetectors and imaging systems, fabricated in mainstream CMOS technology, that are suitable for high-speed, high-sensitivity biological and medical applications. The viability of some of the designs has been verified using device simulation tools and theoretical models. Several pixel structures available in a commercial CMOS process will be compared and their optical response characteristics contrasted. Finally, an imaging system fabricated in a standard CMOS 0.18 micron technology, will be described. Compared to other methods that implement the high-sensitivity photodetectors on a separate die, this system offers higher integration and functionality at a lower price. The system will operate at low power levels, and has the potential to be integrated into larger systems. It can also be a template system that is easily adapted for a wide range of high-speed, high sensitivity biomedical imaging applications.