Real-time analysis of skin capillary-refill processes using blue LED

A method for analysis of skin capillary-refill processes in real time by means of reflection photoplethysmography (PPG) contact probe operating in the blue (438nm ± 30 nm) and infrared (938 nm ± 20 nm) regions of spectrum is proposed. The corresponding prototype hardware and software for measurements have been developed and tested in laboratory. Realtime measurements of finger capillary refill kinetics by this technology have been taken and analyzed. Results demonstrated that both AC and DC components of the blue PPG biosignal are sensitive to capillary occlusion and refill.