An environment-stable hydrogel with skin-matchable performance for human-machine interface

Ionic hydrogel-based sensors have shined a spotlight on wearable electronics. However, the sensitivity and reliability of hydrogel devices are significantly hampered by the weak adhesion of skin-sensor interface as well as inferior temperature tolerance. Here, inspired by the structure and composition of dermis, a novel skin-attachable and environment-stable hydrogel was designed by integrating collagen into the LiCl-containing chemically cross-linked polyacrylamide hydrogel. The hydrogel exhibited skin-like mechanical properties of low modulus, superior stretchability as well as excellent elasticity. Furthermore, the introduction of collagen endowed the hydrogel with robust and seamless interfaces with diverse materials, including the curved skin. As a result, the hydrogel is capable of serving as a human-machine interface for collecting reliable electrocardiography (ECG) signals and discerning various human motions, with high sensitivity (gauge factor = 10.7), fast response, negligible hysteresis as well as extensive monitoring range. Notably, the hydrogel that can mimick the temperature-tolerant mechanism of most organisms possesses persistent stabilization of adhesive, conductive, sensory and mechanical performances at subzero or ambient conditions. The skin-inspired strategy paves an effective way for the design of multifunctional materials with potential applications in next-generation electronics.

基于离子水凝胶的传感器使可穿戴电子设备备受关注。然而，水凝胶器件的灵敏度和可靠性因皮肤 - 传感器界面的粘附性弱以及耐温性差而受到严重阻碍。在此，受真皮结构和成分的启发，通过将胶原蛋白整合到含氯化锂的化学交联聚丙烯酰胺水凝胶中，设计了一种新型的可贴附皮肤且环境稳定的水凝胶。该水凝胶展现出类似皮肤的低模量机械性能、优异的拉伸性以及良好的弹性。此外，胶原蛋白的引入使水凝胶与多种材料（包括弯曲的皮肤）具有牢固且无缝的界面。因此，该水凝胶能够作为人机界面，用于收集可靠的心电图（ECG）信号并识别各种人体运动，具有高灵敏度（应变系数 = 10.7）、快速响应、可忽略的滞后以及广泛的监测范围。值得注意的是，这种能够模拟大多数生物体耐温机制的水凝胶在零下或常温条件下，其粘附、导电、传感和机械性能都能保持稳定。这种受皮肤启发的策略为设计在下一代电子设备中具有潜在应用的多功能材料开辟了一条有效途径。