A Solid-State System for High Temporal Resolution Fluorescence Lifetime Measurements

A system for time-correlated single photon counting applications based on CMOS single photon avalanche diodes is presented. An instrument response function of 79 ps allows a fluorescence decay of high-affinity Ca2+ indicator Oregon Green BAPTA-1 to be analyzed with unprecedented temporal resolution in the two-photon excitation regime. A triple exponential decay model is shown to best fit the fluorescence dynamics of OGB-1.