A flexible self-arched biosensor based on combination of piezoelectric and triboelectric effects

Wearable electronics bring convenience to our lives. Among them, flexible physiological sensors such as pulse sensors that can be used to monitor human health play critical roles. Recently, pulse sensors based on nanogenerators have received extensive attention in recent years, which have considerable properties including high sensitivity, signal-to-noise ratio and low power consumption due to their self-powered mode. Here, a self-powered pulse sensor based on a self-arched nanogenerator (SANG) with a combined effect of piezoelectric and triboelectric is demonstrated for real-time monitoring pulse waveform of the radial artery. The output properties of SANG are related to the morphology of the self-arched structure, which can be easily regulated by adjusting the mass ratio of two types of silicone elastomers of PDMS and Ecoflex. It is a convenient approach compared to conventional ones that should make a different special mold to obtain arched structures. For pulse sensing, the sensitivity and the stability of the SANG are qualified due to its unique self-arched structure and hybrid effect of triboelectric and piezoelectric for converting tiny mechanical signals into electric ones effectively.