Microelectronic photosensors for genetic diagnostic microsystems

Techniques for DNA and protein analysis and separation rely on laser-induced fluorescence (LIF) and employ ultra-sensitive photo-sensors (photo-multiplier tubes or PMT’s, etc.) that are bulky and costly. A key issue for compact and economical instruments is the availability of miniaturized and economical ultra-sensitive sensors. The planar silicon single-photon avalanche diodes (SPAD’s) join typical microelectronic advantages (miniaturization, ruggedness, low voltage, power, and cost) to sensitivity comparable to PMT’s. A compact system is described with a dual SPAD-based LIF detection system and a glass microchip for capillary electrophoresis (CE). Sensitivity better than 3 pM with injection volume 50 pl is achieved in the separation of CY5 DNA labelled fragments.