Bruschini, ClaudioHomulle, HaraldAntolovic, Ivan MichelBurri, SamuelCharbon, Edoardo2019-10-202019-10-202019-10-202019-09-1810.1038/s41377-019-0191-5https://infoscience.epfl.ch/handle/20.500.14299/162116WOS:000489075900002Single-photon avalanche diode (SPAD) arrays are solid-state detectors that offer imaging capabilities at the level of individual photons, with unparalleled photon counting and time-resolved performance. This fascinating technology has progressed at a very fast pace in the past 15 years, since its inception in standard CMOS technology in 2003. A host of architectures have been investigated, ranging from simpler implementations, based solely on off-chip data processing, to progressively "smarter" sensors including on-chip, or even pixel level, time-stamping and processing capabilities. As the technology has matured, a range of biophotonics applications have been explored, including (endoscopic) FLIM, (multibeam multiphoton) FLIM-FRET, SPIM-FCS, super-resolution microscopy, time-resolved Raman spectroscopy, NIROT and PET. We will review some representative sensors and their corresponding applications, including the most relevant challenges faced by chip designers and end-users. Finally, we will provide an outlook on the future of this fascinating technology.OpticsOpticsto-digital converterspad line detectorraman-spectroscopyfill-factorimaging-systemhv cmostimearraysensorresolutiontext::journal::journal article::review article