Highly Responsive and Robust Micro-/Nano-Textured\nSelf-Powered Triboelectric Humidity Sensor

Most advanced humidity sensors of\npresent days are based on the\ntechniques dependent on the external power supplies that require periodic\ncharging and replacement, causing additional cost and complicated\nmanagement issues to the humidity-sensing systems. In this work, this\nproblem has been overcome through a fundamental approach based on\ntriboelectric contact electrification between a pair of the as-fabricated\nhighly functional materials. The concept of self-powered humidity\ndetection with an ultrafast response and relaxation times has been\nsuccessfully demonstrated by introducing a triboelectric humidity\nsensor (TEHS) based on hydrophobic micro-/nano-textured polydimethylsiloxane\nand nano-textured aluminum films. The proposed humidity sensor produces\nan electric output for an external mechanical force that is readily\nrelated to the relative humidity (% RH) level over a wide range of\nambient conditions. The as-fabricated TEHS device shows a record-fast\nresponse time and a relaxation time of 2.2 s and 1.9 s, respectively,\nand has very good linearity in electric output performance in a wide\nhumidity detection range of 10–90% RH. The proposed device\npossesses a highly reliable/stable output performance, which is essentially\nconstant over thousands of contact–separation stability test\ncycles. Moreover, in comparison to a battery-powered commercial humidity\nsensor adopted in this work, the self-powered TEHS device shows a\nsignificantly better performance in terms of response time and relaxation\ntime. Therefore, this work paves the way toward the practical implementation\nof the triboelectric effect-enabled self-powered humidity sensors.