Highly Stretchable and Self-Adhesive Wearable Biosensor Based on Nanozyme-Catalyzed Conductive Hydrogels

A highly stretchable and self-adhesive wearable biosensor is prepared from nanozyme-catalyzed conductive hydrogels. The hydrogels are first prepared from a nanozyme (Ta–Ag) based on polyphenol (tannic acid, Ta) chelate with metal ions (silver ion, Ag+), which possesses peroxidase (POD)-like activity. After that, a huge number of free radicals are formed by the interaction between the Ta–Ag NPs and ammonium persulfate (APS), which initiate the hydrogel polymerization via a facile "one-pot" compositing strategy without ultraviolet (UV) or thermal treatment. The homogeneous distribution of nanozymes in the interpenetrating network of sodium alginate (SA) and polyacrylamide (PAAm) realizes a dermis-mimicking structure in the flexible conductor, named Ta–Ag–SA/PAAm. It simultaneously improves the mechanical properties and conductivity. Similar to the adhesion of mussels, the nanozymes contain abundant phenolic hydroxyl groups, favoring the adhesiveness of hydrogels. Due to the capability of changing conductivity with the strain, the obtained hydrogels are able to accurately monitor different amplitudes of human activities in real time. In addition, the Ta–Ag nanozyme exhibits a good bacterial adhesion capability and thereby enhances the bactericidal efficiency of Ag. Based on the high performance of sensing and antibacterial activity, the obtained Ta–Ag–SA/PAAm hydrogels can be a promising candidate for a broad range of applications, such as adhesive epidemic biosensors and wearable medical patches.