Self-Powered Optical Switch Based on Triboelectrification-Triggered Liquid Crystal Alignment for Wireless Sensing

摘要

Here, a self-powered optical switch (OS) composed of a surface-etched single-electrode triboelectric nanogenerator (TENG) and a polymer-dispersed liquid crystal (PDLC) film is reported. The working principle of the developed OS is that the liquid crystal alignment can be driven by triboelectrification-generated voltage, inducing the PDLC film to rapidly switch its initial translucent state to an instantaneous transparent state. An output voltage of 360 V is generated upon the PDLC film when a nitrile rubber film contacts with the TENG at an area of 25 cm(2) and a velocity of 0.4 m s(-1). As such, a wide dimming range with the relative transmitted light intensity from 0.05 to 0.85 can be achieved for the OS. Enabled by the unique mechano-electro-optical reaction, the effects of a series of structural parameters on the performance of the OS are methodically studied. Particularly, through integrating the OS with a visible-light-operated signal-processing circuit, a complete wireless sensing system with a fully power-free sensing node is developed. The paradigms of hand touching and foot stepping triggered wireless alarms are demonstrated, explicitly showing great potential for the system in many possible interactive human-machine interface applications, such as surveillance, security systems, remote operation, and automatic control.