Balanced Coexistence of Reversible and Irreversible Covalent Bonds in a Conductive Triple Polymeric Network Enables Stretchable Hydrogels with High Toughness and Adhesiveness

Abstract

The application of soft hydrogels to stretchable devices has attracted increasing attention in deformable bioelectronics owing to their unique characteristic, "modulus matching between materials and organs". Despite considerable progress, their low toughness, low conductivity, and absence of tissue adhesiveness remain substantial challenges associated with unstable skin-interfacing, where body movements undesirably disturb electrical signal acquisitions. Herein, we report a material design of a highly tough strain-dissipative and skin-adhesive conducting hydrogel fabricated through a facile one-step sol−gel transition and its application to an interactive human− machine interface. The hydrogel comprises a triple polymeric network where irreversible amide linkage of polyacrylamide with alginate and dynamic covalent bonds entailing conjugated polymer chains of poly(3,4-ethylenedioxythiophene)-co-(3-thienylboronic acid) are simultaneously capable of high stretchability (1300% strain), efficient strain dissipation (36,209 J/m 2 ), low electrical resistance (590 Ω), and even robust skin adhesiveness (35.0 ± 5.6 kPa). Based on such decent characteristics, the hydrogel was utilized as a multifunctional layer for successfully performing either electrophysiological cardiac/muscular on-skin sensors or an interactive stretchable human−machine interface.

Multifunctional, Self-Adhesive MXene-Based Hydrogel Flexible Strain Sensors for Hand-Written Digit Recognition with Assistance of Deep Learning

“…In recent years, continuous progress has been made in hydrogel-based sensors, and many innovative schemes have been used in the research of high-performance hydrogels. − Double-network hydrogels composed of two interpenetrating networks possess high stretchability and high toughness and are an efficient method to prepare tough hydrogels. , Based on this concept, Lin et al proposed the synthesis of agarose and polyacrylamide (PAM) double-network hydrogels by radiation-induced polymerization. Compared with single-mesh PAM hydrogels, this double-mesh PAM hydrogel has higher tensile strength, which is more than 6 times that of single-mesh PAM hydrogels .…”