Polymeric and Soft Materials Laboratory, School of Chemical Engineering and Advanced Institute of Materials Science , Changchun University of Technology , Changchun 130012 , China.
ACS Appl Mater Interfaces. 2019 Jul 17;11(28):25613-25623. doi: 10.1021/acsami.9b08369. Epub 2019 Jul 5.
Currently, flexible wearable hydrogel-based sensors have attracted considerable attention due to their promising applications in a variety of fields. However, concurrently integrating toughness, adhesiveness, self-healing ability, and conductivity into the hydrogel is still a great challenge. Here, casein sodium salt from bovine milk (sodium casein, SC) and polydopamine (PDA, inspired by mussels) were successfully introduced into the polyacrylamide (PAAm) hydrogel system to fabricate a tough and adhesive SC-PDA hydrogel. The hydrogel exhibits splendidly reversible adhesive behavioral bonding toward various materials and even human skin. Moreover, based on the dynamic cross-linking of SC and PDA in the system, the hydrogel has superstretching ability, excellent fatigue resistance, and rapid self-healing ability. In addition, the existence of sodium ions also endowed the SC-PDA hydrogel with sensitive deformation-dependent conductivity to act as a flexible strain and pressure sensor for directly monitoring large-scale human motions (e.g., joint bending) and tiny physiological signals (e.g., speaking and breathing). Therefore, the strategy would broaden the path of a new generation of hydrogel-based sensors for wide applications.
目前，基于柔性可穿戴水凝胶的传感器由于在许多领域的应用前景而引起了相当大的关注。然而，同时将韧性、粘附性、自修复能力和导电性集成到水凝胶中仍然是一个巨大的挑战。在这里，牛初乳中的酪蛋白酸钠（酪蛋白酸钠，SC）和聚多巴胺（PDA，受贻贝启发）被成功引入聚丙烯酰胺（PAAm）水凝胶体系中，以制备坚韧且具有粘附性的 SC-PDA 水凝胶。该水凝胶对各种材料甚至人体皮肤表现出极好的可逆粘附行为。此外，基于体系中 SC 和 PDA 的动态交联，水凝胶具有超拉伸能力、优异的耐疲劳性和快速的自修复能力。此外，钠离子的存在也赋予了 SC-PDA 水凝胶敏感的变形相关导电性，使其能够用作灵活的应变和压力传感器，直接监测大规模人体运动（例如，关节弯曲）和微小的生理信号（例如，说话和呼吸）。因此，该策略将拓宽新一代基于水凝胶的传感器的应用途径。
