Remote Blood Pressure Sensing Using Near-Infrared Wideband LEDs

Long-term and continuous blood pressure monitoring in daily life is important, especially for early detection and prevention of hypertension. The near-infrared (NIR) spectral region, which belongs to the middle of the visible and infrared bands, is the wavelength band with high biological permeability and called as a "living-body window". Our research group developed an NIR wideband LED with a wide emission band in the NIR spectral region and applied the NIR wideband LED in remote blood pressure estimation. The accuracy of remote blood pressure estimation can be improved by using the spatial features of facial images, including multi-wavelength information. In this study, we describe the estimation of remote blood pressure using NIR wideband LEDs. Features in the nasal and lip regions, which contributed to estimating blood pressure, were analyzed using facial NIR images. Furthermore, the root mean square error between the measured and estimated MBP was around 4 mmHg using the NIR wideband LEDs in two of three subjects.