Ultrastretchable,\nHighly Conductive, Rapid Self-Recovery,\nand Antiswelling Hydrogels as Multifunctional Wearable Electronic\nDevices

Abstract

The development of wearable electronic devices requires\nstretchable,\nhighly conductive, self-recovery, and ideally environmentally resistant\nsensors. Hydrogels are ideal candidates for fabricating flexible sensors\ndue to their stretchability and unique ionic conduction pathways.\nHowever, the intrinsic incompatibility of the conductive and elastic\nnetworks in hydrogels and the high hydrophilicity of the hydrogel\nnetwork led to difficulties in obtaining hydrogels with strong mechanical\nproperties, high conductivity, rapid self-recovery ability, and antiswelling\nproperties. Based on the single-core multidentate coordination strategy,\nsingle-core multidentate coordinated chitosan/poly(acrylic acid)/Al³⁺ (CPAL) hydrogels were prepared with Al³⁺ as a\nmetal coordination center and the amino group of chitosan (CS) and\nthe carboxyl group of poly(acrylic acid) (PAA) as coordination atoms.\nThe obtained hydrogels exhibit excellent tensile stress/strain: 1.11\n± 0.04 MPa/2472.79 ± 99.27%, rapid self-recovery capability\n(mechanical properties were fully recovered in 10 min), antifatigue\nproperty, good conductivity (1.09 ± 0.02 S/m), and antiswelling\nproperty. Furthermore, flexible sensors based on CPAL hydrogels demonstrated\nmultiplex mode sensing. It was worth noting that the flexible devices\nbased on CPAL hydrogel could not only use Morse code table to realize\nmechanical-information visualization but also detect the human condition\nin multiple dimensions, including temperature, electromyographic (EMG),\nand electrocardiogram (ECG). In this work, we reported a single-core\nmultidentate coordination strategy that provided a pathway for fabricating\nthe ideal hydrogel-based flexible sensors, showing great potential\nfor wearable electronic devices.