Parallel single molecule detection with a fully integrated single-photon 2×2 CMOS detector array

Abstract

We present parallel single molecule detection (SMD) and fluorescence correlation spectroscopy (FCS) experiments with a fully integrated complementary metal oxide semiconductor (CMOS) singlephoton 2×2 detector array. Multifocal excitation is achieved with a diffractive optical element (DOE). Special emphasis is placed on parallelization of the total system. The performance of the novel singlephoton CMOS detector is investigated and compared to a state-of-theart single-photon detecting module [having an actively quenched avalanche photodiode (APD)] by measurements on free diffusing molecules at different concentrations. Despite the order of magnitude lower detection efficiency of the CMOS detector compared to the state-of-the-art single-photon detecting module, we achieve single molecule sensitivity and reliably determine molecule concentrations. In addition, the CMOS detector performance for the determination of the fraction of slowly diffusing molecules in a primer solution (twocomponent analysis) is demonstrated. The potential of this new technique for high-throughput confocal-detection-based systems is discussed. © 2004 Society of Photo-Optical Instrumentation Engineers.