Diffuse correlation spectroscopy with speckle similarity analysis for blood flow monitoring

Measuring blood flow is critical for assessing tissue perfusion, cerebral function, and vascular health. This work introduces speckle similarity diffuse correlation spectroscopy (SS-DCS), an optical technique for real-time blood flow monitoring. Unlike conventional diffuse correlation spectroscopy (DCS) and speckle contrast optical spectroscopy (SCOS), which rely on temporal or spatial intensity-based statistics, SS-DCS quantifies structural similarity between sequential speckle patterns arising from red blood cell motion. This approach enhances robustness in low-light and motion-sensitive environments. Demonstrated using fiber-based probes in both cerebral and intravascular settings, SS-DCS shows strong potential for integration into wearable and catheter-based flow sensing systems.