Flexible and Multifunctional Biomass-Based Chlorella Hydrogels for High-Performance Wearable Electronics

Biomass-based hydrogels have emerged as promising soft sensing materials to prepare the flexible biomimetic electronic devices for human health monitoring, due to their good stretchability, interfacial adhesion, and biocompatibility. Here, a simple and effective freeze-thaw method is proposed to prepare the flexible and ductile biomass-based Chlorella hydrogels for wearable capacitive strain sensor devices. Ascribing to the formation of dynamic physical cross-linking (hydrogen bonding) between Chlorella and polyvinyl alcohol networks, the obtained Chlorella hydrogels exhibit considerable conductivity and good stretchability (tensile strain > 450%). Moreover, this hydrogel can be used as sensing materials to fabricate the capacitive strain sensor with considerable sensitivity, remarkable mechanical durability, wide working range, and good sensing stability. Furthermore, the conductive hydrogel electrolyte is paired with activated carbon electrodes to build a sandwich-style supercapacitor. The flexible all-solid-state supercapacitor exhibits excellent cycling performance and outstanding stability. Intriguingly, the Chlorella hydrogels also reveal excellent antibacterial performance (against E. coli and S. aureus) and good pH response. These functional features make the biomass-based Chlorella hydrogels valuable for practical healthcare applications.