Low-humidity sensor and biomimetic power supply based on mesoporous silica/polymerizable deep eutectic solvent ionogels

Abstract

Although technologies related to humidity detection and utilization, such as humidity sensors, atmospheric water harvesting, energy collection, and moisture-enabled electrical generation technologies, have been widely reported, there is still an urgent need for effective monitoring and utilization of humidity in low-humidity places. An ideal low-humidity sensor requires a high response, fast response time and low humidity hysteresis. Soft ion power supplies inspired by electric eels convert the chemical potential energy of ion gradients into electrical energy by utilizing humidity, but their production is challenging. This paper reports a new strategy for developing functionalized ionogels based on mesoporous silica and a polymerizable deep eutectic solvent (SiO2@PDES). Due to their strong hydrophilicity, high ionic conductivity, excellent adhesion, flexibility and mechanical strength, SiO2@PDES ionogels can not only detect low humidity but also generate electric power through a reasonably designed device structure. In the 5–30% RH range, the response of the SiO2@PDES humidity sensor reaches 1600%, with negligible humidity hysteresis (0.8% RH). As a biomimetic soft ion power supply, SiO2@PDES ionogels generate a high open-circuit voltage of ∼600 mV at 33% RH, which expands the environmental adaptability of moisture-enabled electrical generation equipment. In addition, the excellent moisture-enabled electrical generation performance endows portable wearable power supplies with high potential for applications such as charging capacitors and lighting LEDs.