Development of laser speckle blood flowmeter for evaluating the physiological function of skin

Objective: We developed and demonstrated laser speckle flowgraphy (LSFG) for two-dimensional (2D) skin blood flow (SBF) measurements to facilitate the noninvasive comparisons of SBF between individuals. Approach: By using morphing technology with a face mesh to compare SBF spatial distributions among individuals, we examined the practicability of SBF measurement with LSFG. Main results: (1) The uniformity of SBF measurement was demonstrated by examinations at different distances and angles for healthy subjects. (2) Mean blur rate (MBR)-a blood flow index of LSFG- exhibited significant correlation with the thermal diffusion method (TDM)-an established blood flow measurement method-suggesting that MBR is an effective index of SBF. (3) Blowout time, the half-width duration/duration of one cardiac cycle, exhibited significant negative correlation with age and positive correlation with stratum corneum hydration. Significance: These results suggest that LSFG is useful for evaluating SBF-related skin properties, and it has significant potential in medicine and cosmetology.