Conformal photoplethysmography sensor with ultrathin architecture for accurate health monitoring

Abstract

Wearable photoplethysmography (PPG) technology is a straightforward method for comfortable and continuous health monitoring. However, the mechanical mismatch and optical noise at the skin–sensor interface compromise the accurate pulse waveform acquisition of PPG sensors. In this work, we propose a conformable PPG sensor to eliminate interfacial optical crosstalk for accurate pulse monitoring. The device possesses an ultrathin thickness of 5.2 µm and a light weight of 8.7 g m⁻², which enable conformal contact between the device and the skin. Due to the elimination of the light reflection noise through close contact and the high sensitivity of the perovskite photodetector, the PPG sensor achieves high pulse signal quality with a perfusion index of 4.4% and a low working illumination intensity of 25.3 µW cm⁻². Furthermore, heart rate variability analysis and continuous blood pressure monitoring are performed using these accurate pulse signals. This work provides a reliable interface engineering strategy for eliminating optical noise in wearable health sensing electronics.