Highly stretchable and bio-based sensors for sensitive strain detection of angular displacements

Flexible and electrically conductive hydrogels were fabricated by incorporating carboxylic multiwall carbon nanotubes (c-MWCNTs) into bacterial cellulose (BC) membranes by electrostatic self-assembly using bovine serum albumin (BSA). A piezoresistive strain sensor assembled by c-MWCNTs/BSA/BC hydrogel exhibited 70% stretchability and excellent cycling stability. It was able to accurately detect diverse large-scale human motions, including finger knuckle, wrist bending, knee joint, and elbow joint. The eco-friendly BC provided an inexpensive and renewable substrate for flexible strain sensors. Graphical abstract