Characterization of a fiber-coupled SPAD camera system for deep-tissue blood-flow measurement using diffuse correlation spectroscopy
Diffuse correlation spectroscopy (DCS) is a promising technique for noninvasive measurement of blood flow, especially for cerebral blood flow where other noninvasive techniques have shortcomings. Conventional DCS often requires multiple simultaneous measurements to enhance the signal-to-noise ratio (SNR) especially when probing deep into the brain with large source-detector separations where photons are scarce. However, this limits scalability when using discrete optical detectors. This study demonstrates the application of the 500 x 500 single-photon avalanche diode (SPAD) array, SwissSPAD3, coupled with a custom field-programmable gate array (FPGA) design, which enables significant increases in SNR compared to conventional DCS systems. We validate the fiber-coupled SPAD camera system against a lab-standard CW-DCS system in two-layer liquid phantoms and in human measurements, and demonstrate robust blood-flow tracking at source-detector separations up to 3.25 cm. These results support SPAD-based parallel detection as a scalable route to improved deep-tissue DCS performance in humans.
Stony Brook University
École Polytechnique Fédérale de Lausanne
École Polytechnique Fédérale de Lausanne
École Polytechnique Fédérale de Lausanne
École Polytechnique Fédérale de Lausanne
École Polytechnique Fédérale de Lausanne
Stony Brook University
2026-01-02
medRxiv
EPFL