Fabrication of alginate-P(SBMA-co-AAm) hydrogels with ultrastretchability, strain sensitivity, self-adhesiveness, biocompatibility, and self-cleaning function for strain sensors

Conductive hydrogels have attracted a myriad of interest due to their potential applications for human motion monitoring, personal healthcare diagnosis and so forth. However, fabrication of hydrogel-based strain sensors integrating with ultrastretchability, adhesiveness, strain sensitivity, biocompatibility, and self-cleaning function is still a challenge. Herein, a new type of semi-interpenetrating multifunctional hydrogels, which integrated all above practical features magically were prepared via a facile one-pot in-situ radical copolymerization method. Thereinto, [2-(methacryloyloxy) ethyl] dimethyl-(3-sulfopropyl) ammonium hydroxide (SBMA) and acrylamide (AAm) copolymers cross-linked by N , N ′-Methylenebisacrylamide (MBAA) served as the soft and functional matrix, whereas alginate was employed as the enhanced component. The transparent zwitterionic hydrogels had a max elongation and ionic conductivity of 1353% and 0.15 S/m, respectively. They could adhere onto various surfaces, including steel, glass, skin, and rubber. The repeatable adhesiveness, linear strain sensitivity within 0%–250% tensile strain and 0%–30% compressive strain provided remarkable working range and using stability. What's more notable was that the biocompatibility and self-cleaning function tested by MTT, live/dead assay, allergy patch tests, and plate colony-counting method imparted great possibility of practical application for strain sensors to hydrogels from a biological point of view.