Multifunctional conductive composite hydrogel facilitated by high-functionality crosslinker strategy for strain sensing applications

The inferior mechanical performance and low conductivity limit the applications of hydrogels particularly in flexible electronics and tissue engineering. In this study, a highly robust and conductive hydrogel is fabricated through unique strategy of high-functionality crosslinker. The reduced graphene oxide (RGO) and chitosan (CS) act as the high-functionality crosslinker and bridge the polymers without involving any organic crosslinker. Chitosan (CS) is added for the reduction of graphene oxide (GO), while the ionic liquid (IL) facilitates the dispersion of RGO. Compared to the conventional PAA and CS hydrogels that use organic crosslinkers, the as-prepared composite hydrogel exhibits a significantly improved tensile strength. Interestingly, this technique can be used for application of coating on cotton fabric to improve its characteristics. Moreover, the sensing ability of high-strength hydrogel was also evaluated for applied strain. Based on this strategy, the mechanical properties and conductivity of the gel can be decoupled and separately tuned. The fabrication method in this work is facile and cost-effective, broadening its application in producing robust deformable electronics on bulk scale.