EVALUATION OF BLOOD VESSEL STIFFNESS INDEX USING OPTICAL RECORDING WITH A SMART PHONE

In this study, we acquired video images from the index finger of subjects using white light emitting diode (WLED) of a smart phone as light source and a camera as optical detector on a frame-by-frame basis, converted the acquired images into red, green and blue (RGB) formats and detected the images in the form of photoplethysmography (PPG) waveforms through real-time video signal processing. Through utilization of secondary derivative photoplethysmography (SDPTG), a PPG second order differential form, the parameters used to monitor arterial stiffness of b/a ratio, d/a ratio and Aging Index (AI) were calculated. From the results of correlation analysis between the value calculated from smart phone and the value calculated by reference equipment, statistically significant results of b/a ratio (r=0.919, p<0.001), d/a ratio (r=0.889, p<0.001) and AI (r=0.938, p<0.001) were obtained. Based on this, we carried out evaluation on the arterial stiffness such as arteriosclerosis using optical devices of smart phones.