Natural cellulose reinforced multifunctional eutectogels for wearable sensors and epidermal electrodes

Wearable electronics significantly impact health monitoring, clinical care, and human-machine interfaces. Eutectogels, which utilize deep eutectic solvents (DES) address the drawbacks of hydrogels, such as weight loss and poor temperature tolerance, as well as the high costs and toxicities associated with ionogels. Despite these advances, most eutectogels serve only as sensors or epidermal electrodes and rarely fulfill both functions simultaneously. In this study, we present a multifunctional eutectogel designed to function in both ways. Incorporating natural cotton cellulose nanofibers as nanofillers reinforced the tensile strength of the resultant eutectogel by 7.47 times compared to that of the pure eutectogel, reaching 4.93 MPa. This eutectogel exhibited high ionic conductivity (1.22 S m^-1), strong adhesion (1562.2 kPa to iron), self-healing ability (80.37% strain recovery and 80.53% tensile strength recovery), a broad temperature tolerance (-40 to 80 °C), and antibacterial properties. It demonstrates high sensitivity for the real-time strain detection of human activities and accurately captures electrophysiological signals, enabling the control of a small car. This versatile eutectogel has excellent potential for use in flexible wearable electronics.