Highly Stretchable Sensitive Multiscale Hydrogel Inspired\nby Biological Muscles for Wearing Sensors

Hydrogels have attracted substantial\nresearch interest for application\nin wearable electronics due to their stretchability, elasticity, and\ncompliance. However, most hydrogels could not satisfy the application\nrequirements for high-performance wearable sensors due to their poor\nsensitivity, low mechanical properties, and sensing detection range\nuntil this day. Inspired by the fascia in biological muscles, we propose\na strategy to form entangled “clusters” through the\ndense entanglement between highly cross-linked elastic hydrogel microspheres\nand polymer segments, and prepared a multiscale hydrogel with high\nsensitivity and mechanical toughness. This strategy embedded highly\nswollen hydrogel microspheres (with different pore sizes) to act as\nthe microregions of dense entanglement in the soft matrix to adjust\nthe microstructure of multiscale gel. When pressure was applied, this\nstructure could provide a fast response due to the stack layer formed\nby microspheres and soft matrix produced effective stress distribution,\nresulting in the outstanding sensitivity of the multiscale hydrogel\n(<i>S</i> = 1.1 kPa<sup>–1</sup>) in the pressure\nrange of 0–50 kPa. The distinct microspheres functioning as\nmicroscale joint areas significantly augment energy dissipation, culminating\nin exceptional mechanical stability, ultrastretchability (≈1050%),\nand high strength of the multiscale hydrogel. The most notable progress\nwas that the synthesized multiscale hydrogel not only combined the\nabove advantages but also simultaneously solved multiple dilemmas\nof tedious synthesis steps, high cost, and poor durability. Besides,\nthe multiscale hydrogel also had excellent antibacterial properties\nand biocompatibility, which enabled them to have large-scale application\npotential in wearable and implantable electronic devices. Our research\ncould provide a universal approach to the creation of robust, flexible,\nwearable, and sensitive sensors, significantly increasing the uses\nof stress sensors in wearable technology.