SignificanceIn 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 noninvasively poses a persistent challenge, primarily attributed to the difficulty of accessing and obtaining signal from the brain.AimOur study aims to introduce a compact speckle contrast optical spectroscopy device for noninvasive CBF measurements at long source-to-detector distances, offering cost-effectiveness, and scalability while tracking blood flow (BF) with remarkable sensitivity and temporal resolution.ApproachThe wearable sensor module consists solely of a laser diode and a board camera. It can be easily placed on a subject’s head to measure BF at a sampling rate of 80 Hz.ResultsCompared to the single-fiber-based version, the proposed device achieved a signal gain of about 70 times, showed superior stability, reproducibility, and signal-to-noise ratio for measuring BF at long source-to-detector distances. The device can be distributed in multiple configurations around the head.ConclusionsGiven its cost-effectiveness, scalability, and simplicity, this laser-centric tool offers significant potential in advancing noninvasive cerebral monitoring technologies.
Diffusing Wave Spectroscopy (DWS) employs non-invasive techniques to study dynamic behaviors within scattering mediums. This involves detecting speckle light patterns from the moving media and gauging speckle decorrelation time for dynamic quantification. A specific form of DWS is Speckle Visibility Spectroscopy (SVS), which employs spatial ensembles by utilizing a high-pixel-count cameras to capture multiple speckles in a single frame. To further increase SNR at low signal level, one combines interferometric techniques with SVS to form interferometric SVS (iSVS).
In this talk, I will present the benefits and constraints associated with the utilization of interferometric detection (iSVS) over direct detection (SVS). Surprisingly, we found that iSVS does not always outperform SVS, but it does emerge as the prevailing choice in most cases.
Measuring blood flow on the head is an indirect yet crucial way to access or quantify brain activity non-invasively, useful for diagnosing traumatic brain injuries by looking at the changes of blood flow. However, measuring the cerebral blood flow (CBF) remains challenging, principally due to the ability to reach and collect signal from the brain. In this talk, I will present our efforts in building an affordable, compact, and portable laser device for real-time Cerebral Blood Flow (CBF) monitoring. Our technique draws upon the speckle visibility spectroscopy technique, using the spatial ensemble of the speckle field to evaluate blood flow dynamics.
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