Three-wavelength SPAD-based photoplethysmography

Continuous and real-time monitoring of cardiorespiratory signals by portable and accurate instrumentation is very important for the early diagnosis of cardiovascular diseases. We aim to present a novel photoplethysmography device to assess changes in blood oxygen saturation and beat-by-beat pulse waves of finger blood volumes not affected by possibly occurring variations in oxygen saturation. For this purpose, our device works at three light wavelengths simultaneously and is based on a Single-Photon Avalanche Diode to evaluate the feasibility of using this technology in contact photoplethysmography. Our preliminary validation shows that the device is robust against movement artifacts and provides measures that reflect the physiological cardiorespiratory adaptations to the Valsalva maneuver, suggesting its overall reliability and possible use in cardiovascular monitoring.