  In the realm of cerebrovascular monitoring, primary metrics typically include
blood pressure, which influences cerebral blood flow (CBF) and is contingent
upon vessel radius. Measuring CBF non-invasively poses a persistent challenge,
primarily attributed to the difficulty of accessing and obtaining signal from
the brain. This study aims to introduce a compact speckle visibility
spectroscopy (SVS) device designed for non-invasive CBF measurements, offering
cost-effectiveness and scalability while tracking CBF with remarkable
sensitivity and temporal resolution. The wearable hardware has a modular design
approach consisting solely of a laser diode as the source and a meticulously
selected board camera as the detector. They both can be easily placed on the
head of a subject to measure CBF with no additional optical elements. The SVS
device can achieve a sampling rate of 80 Hz with minimal susceptibility to
external disturbances. The device also achieves better SNR compared with
traditional fiber-based SVS devices, capturing about 70 times more signal and
showing superior stability and reproducibility. It is designed to be paired and
distributed in multiple configurations around the head, and measure signals
that exceed the quality of prior optical CBF measurement techniques. Given its
cost-effectiveness, scalability, and simplicity, this laser-centric tool offers
significant potential in advancing non-invasive cerebral monitoring
technologies.
