Strong adhesive, high conductive and environmentally stable eutectogel based on “Water in deep eutectic Solvent”: Ultrasensitive flexible temperature and strain sensors

Abstract

Eutectogel is a promising candidate of conductive materials for flexible electronic sensors. However, the existing eutectogel sensors still have some problems such as poor mechanical properties and antifatigue ability, limited ionic conductivity, and strong hygroscopicity. Herein, an eutectogel is fabricated via one-stop photoinitiated copolymerization of acrylic acid, hydroxyethyl acrylate, and highly branched modified polyethyleneimine in “water in deep eutectic solvent”. The optimized eutectogel exhibits strong adhesive strength (132 ± 9 kPa, with porcine skin), ultra elongation (3500 %), high conductivity (2.7 ± 0.1 mS cm−1), long term antidrying and antifreezing (∼30 d) in a wide range of working temperatures (−40 − 60 °C), flame resistance, biocompatability, and excellent resistance ability to tear and crack propagation. The superb flame resistance and sensitive response to temperature offer a potential application in fire alarm. Besides, this gel-based wearable strain sensors can sensitively monitor and differentiate large body joint movements and subtle muscle motions. The highly distinguishable and reproducible signals can be recorded while further utilizes as sensors for detecting human healthcare accurately and continuously in medical mobile electrocardiogram machine for a long time. This work provides a new strategy for constructing eutectogel based wearable devices and electronic devices with excellent performance.