CMOS Geiger-mode avalanche photodiode detectors for time and intensity resolved measurements

Geiger-mode avalanche photodiode detectors are produced using standard CMOS fabrication methods. We have produced integrated circuits that include the Geiger-mode photodetector and digital signal processing circuits. Our current design includes sixteen photon counting detector elements, with bias control, active quenching circuits, and integrated counters at each pixel. The detectors are used to measure chemiluminescence from horseradish peroxidase conjugated antibodies in sub-microliter samples using an optical waveguide. The detector array has been coupled with an external field programmable gate array (FPGA) to perform multi-channel, all digital, time resolved fluorescence measurements of quantum dot nanoparticles and the pH dependence of the fluorescence lifetime of fluorescein dye.