Abstract
Photoplethysmography (PPG) is a simple noninvasive technique for the detection of multiple cardiovascular parameters, such as heart rate, blood oxygen saturation (SpO(2)), systolic blood pressure, and diastolic blood pressure. However, the current commercial PPG technology is limited by several factors, including rigidity, bulkiness, high cost, high power consumption of ∼10's mW, poor operational stability under ambient conditions, and susceptibility to motion artifacts. In this work, we overcome many of these limitations using a novel self-powered, miniaturized, low-cost, stable PPG sensor based on a simple CMOS-compatible fluorite-type ferro/pyroelectric Hf(x)Zr(1-x)O(2) thin-film photodetector device. Our novel self-powered photodetector shows 26% higher responsivity and 23% improved sensitivity (perfusion index of 3.7%) for sensing blood volume changes in microvascular tissues compared to conventional PPGs, and a very high accuracy (<2% error) in the estimation of SpO(2). The simple sensor has strong prospects for replacing current PPG sensors for health monitoring applications.