A toughened, transparent, anti-freezing and solvent-resistant hydrogel towards environmentally tolerant strain sensor and soft connection

Abstract

Low-temperature tolerant and solvent-resistant soft electronic devices have received increasing attention due to their excellent adaptability under multiple environments. Herein, the poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and zwitterionic betaine (ZB) are introduced into the Al3+ cross-linked polyacrylic acid (PAA) networks to construct a multipurpose hydrogel (PAA-Al3+/PEDOT:PSS/ZB), which exhibits superior stretchability (1457 %), tensile strength (1.43 MPa), freeze-tolerance (−35 °C) and solvent-resistant capability. Furthermore, a strain sensor with multi-environmental stability is fabricated based on this hydrogel, which could not only accurately monitor the different human motions (finger bending, writing, swallowing, breathing, walking, head-up/down and wrist-up/down) at room temperature, but also reliably distinguish the various mechanical deformations in diverse solvent media (water, cyclohexane and methylbenzene) and harsh climatic condition (−35 °C). In addition, a flexible tube-shaped PAA-Al3+/PEDOT:PSS/ZB hydrogel is also successfully developed in the specific reaction mold, which can be utilized as a soft connection for the tap or two severed glass tubes to transport different liquids benefiting from the significant mechanical toughness and anti-swelling property. It is anticipated that the as-prepared hydrogel may be a promising flexible material with multi-environmental stability applying in biomedical devices, soft robotics, electronic skins and wearable sensors under complex environments.