Low-Temperature tolerance and conformal adhesion zwitterionic hydrogels as electronic skin for strain and temperature responsiveness

Abstract

Flexible electronics have been extensively explored for health monitoring, artificial intelligence, and soft robotics. However, it remains challenging to simultaneously achieve temperature and strain monitoring over a wide perception range that are highly analogous to natural human skin. Herein, an intelligent thermosensation zwitterionic hydrogel with superior low-temperature tolerance and conformal adhesion was successfully prepared for strain-temperature dual-modal sensors, based on the temperature-dependent self-association interactions of sulfobetaine methacrylate (SBMA) polymer chains and the incorporation of thermosensitive TEMPO-oxidized cellulose/polyaniline nanofibers (CPA NFs) in glycerol-water binary solvent system. Significantly, the TEMPO-oxidized cellulose acting as the reinforced skeleton guided the in-situ polymerization of polyaniline, while the tunneling current activated by thermal vibration of CPA NFs and the charge transfer caused by the spatial position adjustment collectively contributed to the superimposed signal recognition ability. By leveraging the glycerol molecules to inhibit the ice crystal growth without the compromise of flexibility (1095 %), strain sensitivity (GF = 1.25), and thermal responsiveness (TCR = 2.01% °C−1), the accurate determination paradigm for dual-modal strain and temperature sensor over a wide temperature range (-40–80 °C) was subtlyachieved. Additionally, we corroborated that the conformal adhesion between zwitterionic active sites (e.g. –N+(CH3)3 or -SO3-) and dynamic interfaces was critical for minimizing interface slippage and delamination, as well as maintaining real-time electricalsignal stability. The assembled zwitterionic epidermis sensor array that conformally adhered to fingers could realize the subtle signal identification and localized temperature detection, which presented promising prospects for designing the multi-modal skin-like responsiveness electronic skins that suitable for harsh temperature conditions.