Food-Inspired, High-Sensitivity Piezoresistive Graphene Hydrogels

There is a societal need for electronic materials to meet sustainability standards to facilitate the creation of easily disposed of green devices. Commonly, polymer-based materials applied to create strain-sensing devices utilize hazardous solvents and nonrecyclable resources that are unsuitable for these goals. Here, we demonstrate a simple system based on food-grade algae that we mix with a pristine, aqueous graphene suspension to create nanocomposite films that were processed into biodegradable hydrogels, again using food-based culinary products. We report our hydrogels to have record low Young’s moduli of ~0.6 Pa for a nanocomposite and record high gauge factors of G ~ 50 for a hydrogel system. Our sustainable graphene algae hydrogels were so sensitive that they could measure an object just 2 mg in mass, equivalent to a single rain droplet, impacting their surface.