Self-Healable Conductive Nanocellulose Nanocomposites for Biocompatible Electronic Skin Sensor Systems

Electronic skins are developed for applications such as biomedical sensors, robotic prosthetics, and human–machine interactions, which raise the interest in composite materials that possess both flexibility and sensing properties. Polypyrrole-coated cellulose nanocrystals and cellulose nanofibers were prepared using iron­(III) chloride (FeCl3) oxidant, which were used to reinforce polyvinyl alcohol (PVA). The combination of weak H-bonds and iron coordination bonds and the synergistic effect of these components yielded self-healing nanocomposite films with robust mechanical strength (409% increase compared to pure PVA and high toughness up to 407.1%) and excellent adhesion (9670 times greater than its own weight) to various substrates in air and water. When damaged, the nanocomposite films displayed good mechanical (72.0–76.3%) and conductive (54.9–91.2%) recovery after a healing time of 30 min. More importantly, the flexible nanocomposites possessed high strain sensitivity under subtle strains (