Bacterial cellulose hydrogel for sensors

Biohydrogel–based flexible sensors have attracted enormous and growing attention for personalized mobile equipment, human–machine interface units, wearable medical–healthcare systems, and bionic intelligent robots. As a natural biomass, bacterial cellulose (BC) has multiple advantages including low cost, renewability, easy processability, biodegradability, high purity, easy to be modified and functionalized, as well as appealing mechanical performance. Given these merits, BC could act as a substrate, a matrix, or a reinforcing agent in the form of hydrogel and endows favorable properties for wearable sensors and intelligent electronics. Here, the report provides an overview of the structure–property–application relationships of BC hydrogel and its applications in flexible sensors. The unique molecular structural features and the formation approaches of BC are briefly introduced. The focus then turns to the fabrication and functionalization approaches for functional BC hydrogel preparation, followed by an emphasis on the interfacial interaction modulation strategy owing to BC’s abundant active hydroxyl group. Recent advances in BC hydrogel–based sensors including strain, pH, electroactive, and thermal sensors are then summarized. Finally, a brief prospectus for the development of BC hydrogels in the future is provided.