Microelectronic ultrasensitive detectors for chip electrophoresis microsystems.

Techniques for DNA and protein analysis and separation rely on laser-induced fluorescence (LIF) and employ ultra-sensitive photo-sensors (photo-multiplier tubes PMT's, etc.) that are bulky and/or 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 system is described with a SPAD-based LIF detection system and a glass microchip for capillary electrophoresis (CE). A detection limit of 0.19 ng/mu L was verified for fluoresceine labeled oligonucleotides; the performance of the setup was tested in the separation of DNA fragments.