In this paper we present an array of 48 Single Photon Avalanche Diodes (SPADs) specifically designed for multispot Single Molecule Analysis. The detectors have been arranged in a 12×4 square geometry with a pitch-to-diameter ratio of ten in order to minimize the collection of the light from non-conjugated excitation spots. In order to explore the trade-offs between the detectors' performance and the optical coupling with the experimental setup, SPADs with an active diameter of 25 and of 50µm have been manufactured. The use of a custom technology, specifically designed for the fabrication of the detectors, allowed us to combine a high photon detection efficiency (peak close to 50% at a wavelength of 550nm) with a low dark count rate compatible with true single molecule detection. In order to allow easy integration into the optical setup for parallel single-molecule analysis, the SPAD array has been incorporated in a compact module containing all the electronics needed for a proper operation of the detectors.
Keywords: FRET; Photon Counting; SPAD array; Single-Photon Avalanche Diode (SPAD); high throughput; single molecule.