Anti-freezing organohydrogel triboelectric nanogenerator toward highly efficient and flexible human-machine interaction at − 30 °C

Highlights: • A type of anti-freezing ionic conductive organohydrogels was designed, with modulus of 29.2 kPa and stretchability of 700% at − 30 ℃. • Anti-freezing, stretchable and transparent triboelectric nanogenerators (TENGs) were prepared by using the organohydrogels as flexible electrodes. • The TENGs were further developed as self-powered sensors and demonstrated using as wearable keyboards by typing at − 30 ℃. Human-machine interaction is crucial for mobile communications, Internet of Things, intelligent medical care, and intelligent robots. There is an increasing interest to develop the next generation of flexible human-machine interactive devices based on stretchable ionic conductive polymer gels. However, due to the nature of polymer gels, the devices turn brittle and the ionic conductivity dramatically drops at subzero temperatures, thus restricted their applicable temperature range. Herein, anti-freezing organohydrogels consist of polyacrylamides/nano-clays networks absorbed with ethylene glycol (EG)/water were designed. The anti-freezing binary solution provides excellent properties for organohydrogels at − 30 °C, including tensile modulus of 29.2 kPa, an ultimate tensile strain of 700%, the ionic conductivity of 1.5 × 10⁻³ S m⁻¹, transparency of 91%, and rapid self-healing. The flexible organohydrogels electrodes were assembled with elastomers to prepare triboelectric nanogenerators (TENGs), which were further attached on fingers to develop human-machine interactive keyboards. The voltage signals produced by the keyboards in contact with many surfaces were collected, coded, and interpreted as letters and punctuations, then displayed on a monitor. We demonstrated typing by using the self-powered flexible keyboard at − 30 °C. This work may benefit the development of anti-freezing soft materials, self-powered sensors, and wearable human-machine interaction communication device systems.