Hydrogen-bonding-enhanced green wearable sensors with high generation performance and low Young's modulus

Abstract

Triboelectric nanogenerators (TENGs) have promising potential for applications in self-powered wearable sensors, and the use of natural materials as the friction layer to develop environmentally friendly TENGs has attracted extensive research. However, current strategies for improving the output performance of natural TENGs face difficulties in obtaining both high generation performance and ideal mechanical properties (or environmental friendliness). In this study, additional hydrogen bonds provided by the glycerol plasticizer and mineral diatomite are introduced into the hard chitosan (CS) polymer matrix to increase CS TENG performance and decrease Young's modulus simultaneously, while maintaining its environment friendly nature. The CS–glycerol–diatomite with a Young's modulus of 0.32 kPa shows excellent TENG performance with an open-circuit voltage as high as 205 V, which is 3.8 times than that of CS-based TENGs. The hydrogen bonding with CS chains is detected by FTIR, XRD, DSC and theoretical calculations, and the generation performance is compared through sequential control of filler addition. Finally, a high-output performance CS TENG sensor could identify different respiratory states, achieving the highest accuracy rate of 96.67%. The hydrogen bond introduction strategy with a plasticizer and mineral provides a new idea that can effectively improve the green TENG composed of natural polymer friction layers.