Flexible optoelectronics based on inorganic functional components have attracted worldwide attention due to their inherent advantages. However, the power supply problem presents a significant obstacle to the commercialization of wearable optoelectronics. Triboelectric nanogenerator (TENG) technology has the potential to realize self-powered applications compared to the conventional charging technologies. Herein, a flexible self-powered blood oxygen monitoring system based on TENG was first demonstrated. The flexibility of the TENG is mainly due to the inherent properties of polydimethylsiloxane (PDMS) and the continuously undulating surface of crumpled gold (Au) and the rough surface on the electrode and PDMS effectively increased the output performance. The output voltage, output current density, and power density were 75.3 V, 7.4 μA, and 0.2 mW/cm2, respectively. By etching the sacrificial layer, we then derived a flexible blood oxygen and pulse detector without any obvious performance degradation. Powered by the TENG, the detector is mounted onto the thumbnail, from where it detects a stable photoplethysmography (PPG) signal which can be used to calculate the oxyhemoglobin saturation and pulse rate. This self-powered system provides a new way to sustainably monitor physiological parameters, which paves the way for development of wearable electronics and battery-free systems.
Keywords: blood oxygen; flexible electronics; self-power; triboelectric nanogenerator.