Self-adhesive, self-healing, conductive organogel strain sensors with extreme temperature tolerance

Abstract

Conductive hydrogels have highlighted their potential in the fields of electronic skin, soft robotics, and healthcare monitoring, due to their excellent flexibility, tissue-like compliance, and biocompatibility. However, most conductive hydrogels suffer from poor mechanical strength, unsatisfied self-healing properties, and bad temperature tolerance. Herein, we designed a novel ionic organogel based on poly(acrylic acid-co-4-vinylphenylboronic acid) (P(AA-co-VBA)), polyethylene oxide (PEO), tannic acid (TA), and LiCl by simple one-pot radical copolymerization. After elaborately optimizing, the obtained organogel has extremely high mechanical properties (a tensile strength of 0.25 MPa, and an elongation at break of 3200%), good self-healing properties (24 h, 81% self-healing efficiency), and extreme temperature tolerance (from −20 °C to 90 °C). The strain sensor based on the obtained organogel had excellent self-adhesive properties and could closely adhere to the skin to detect temperatures from 0 °C to 42 °C (temperature coefficient of resistance, TCR, at 35 °C is −0.10468 °C⁻¹). The strain sensors also monitor large, subtle body movement within a wide temperature range. It is foreseeable that this ionic organogel will provide new inspiration for the development of flexible strain sensors.