Thermogalvanic hydrogels for self-powered temperature monitoring in extreme environments

Abstract

Thermogalvanic hydrogels have been highlighted in the design of flexible thermoelectric cells and sensors on account of their excellent physicochemical properties such as high thermal sensitivity, stretchability, and portability. However, the incident freezing and drying behaviors of hydrogels by using water solvent as the dispersion medium limit their scope of application greatly. Herein, a gel electrolyte-based thermogalvanic device with I⁻/I₃⁻ as a redox pair is fabricated, which shows a preferred temperature tolerance (−20 to 80 °C) and superior anti-drying capacity at reduced vapor pressure. These features stem from weakening the hydrogen bonds between water molecules by using a simple binary solvent strategy. Considering its decent thermogalvanic response, a gel-based temperature monitoring system was developed, which can be used as a comfortable electronic skin for human body monitoring. It could also be applied to build up a smart window system for self-powered monitoring of indoor or outdoor temperatures, even in extreme weather and climate events.