CMOS single-photon detector for advanced fluorescence sensing applications

Fluorescence lifetime measurement is used in biological research to enhance the contrast of fluorescence images. The outstanding sensitivity that can be achieved with this method is obtained at the expense of a high data throughput. A substantial data reduction can be achieved using the time-gated technique, which consists in counting the number of photons occurring inside different time windows. Thanks to the recent developments in the realization of Single Photon Avalanche Diodes (SPAD) in standard CMOS technologies, this technique can be monolithically implemented on-chip. In this work, three different detectors fabricated within a 0.35 ▪m High Voltage CMOS technology will be described, focusing onto their use in lifetime imaging. The sensors have been designed for different optical setups and for different applications, ranging from Fluorescence Lifetime Imaging Microscopy to miniaturized Lab-on-Chip. The advantages and limitation of the proposed sensors will be pointed out and a case study of a specific application will be presented.