Mechanically robust, degradable and conductive MXene-composited gelatin organohydrogel with environmental stability and self-adhesiveness for multifunctional sensor

Abstract

MXene-based conductive hydrogels have attracted immense interest as sensing materials for flexible wearable sensors due to their mechanical flexibility and high sensitivity. However, the low stability of MXene in aqueous media severely deteriorates the performances of MXene-based conductive hydrogels. Meanwhile, for their applications in advanced sensors, high mechanical strength, good environmental stability, self-adhesiveness, multiple sensory function combined with biodegradability are vital but can be rarely met in one platform. Herein, we first prepare stable MXene/gelatin dispersion by encapsulating MXene with gelatin to hinder restacking and oxidation of MXene nanosheets in water. Based on the MXene/gelatin dispersion, a high-strength and conductive MXene-composited gelatin (MCG) organohydrogel with excellent environmental stability and self-adhesiveness is fabricated by simply soaking the MCG pre-hydrogel in tannic acid (TA) water/glycerol solution. This design allows the formation of both multiple supramolecular crosslinked interactions and water/glycerol binary solvent system. The prepared MCG organohydrogel derived from natural constituents exhibits outstanding mechanical properties (such as high tensile strength and stretchability), excellent freezing resistance, moisturizing retention properties and self-adhesiveness, yet degrades fully when disposed. The resultant MCG hydrogel-based versatile sensors exhibit both high strain-sensitivity and thermosensitive capacities, realizing the application in the measurement of human motion and body temperature, providing a promising route to fabricate degradable sensing materials combined with all the favourable attributes for advanced electronics.