Robust versatile nanocellulose/polyvinyl alcohol/carbon dot hydrogels for biomechanical sensing

A new type of nanocellulose/poly(vinyl alcohol)/carbon dot (NPC) multifunctional hydrogel was successfully fabricated by an one-step in-situ hydrothermal method. The one-pot strategy led to the formation of a complex hydrogen bonding/dynamic boric acid ester/nitrogen-doped carbon dots network, and endowed the hydrogel with multifunctionality. The hydrogel underwent self-healing at room temperature (25 °C) and exhibited double-emission fluorescence and high mechanical strength (tensile strength of up to 2.98 MPa). An NPC hydrogel-based capacitive sensor exhibited remarkable linear capacitance responsiveness toward pressure, strain, and glucose concentration, and enabled real-time synchronous quantitative pressure/glucose sensing with multiple linear correlations, which was a key performance criteria for biomechanical sensors. The versatility and multiple advantages of the as-prepared hydrogel demonstrate the potential of biological–mechanical sensing materials using natural cellulosic biomass.