Super stretchability, strong adhesion, flexible sensor based on Fe3+ dynamic coordination sodium alginate/polyacrylamide dual-network hydrogel

Bionic hydrogel sensors have been known as promising alternatives to biomimetic skins. Here, a bionic hydrogel sensor based on sodium alginate (Alg), polyacrylamide (PAAM) and Fe3+ have been fabricated by a simple one-pot method, shows super stretchability, excellent adhesion and conductivity. The Fe3+/Alg-PAAM hydrogel was endowed with a dynamic coordination dual-network structure based on controllable Fe3+ penetration and free radical polymerization dual effect, which was equipped with the synergistic properties of high storage modulus (2200 KPa), super stretchability (1800%) and strong adhesion to various substrates (glass adhesion with 61.8 KPa). Moreover, due to abundant free ions, the Fe3+/Alg-PAAM hydrogel displays good conductive behavior, and further shows excellent sensing behavior and strain sensitivity as a skin sensor to monitor human movement. This work enriches the design and preparation strategies of flexible hydrogels to promote the application of Alg-based materials for the wearable electronic devices and intelligent monitoring systems.