Highly Conductive and Durable MXene/CNC/PEDOT:PSS-PNIPAm Hydrogel for Bioinspired Self-Sensing Soft Actuators

Living organisms in nature can sensitively perceive environmental stimuli and respond through rapid adaptive deformation. Inspired by this functionality, self-sensing hydrogel actuators have been developed, offering broad potential in areas such as information encryption, flexible wearables, and human-machine interfaces. Here, we report a versatile strategy for fabricating self-sensing hydrogel actuators with simultaneously high electrical conductivity and excellent mechanical durability. A robust interpenetrating network is constructed between surface-functionalized MXene nanomonomers (T-MXene) and modified cellulose nanocrystals (CNC-Vi), which markedly enhances the stability of poly(N-isopropylacrylamide) (PNIPAm) hydrogel. In addition, incorporation of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) further enhances the composite's electrical conductivity while simultaneously improving the environmental adaptability. The resulting hydrogel exhibits high conductivity (14.92 S m^-1), remarkable strain sensitivity (GF of 2.17 to 7.23), and outstanding durability. Leveraging these features, we realize reliable information encryption and storage, as well as wearable motion sensors capable of sensitive and precise motion detection. Moreover, the hydrogel system serves as an excellent platform for constructing high-performance self-sensing actuators. By inducing a gradient alignment of T-MXene/CNC-Vi under a direct-current (DC) electric field, we develop a shape-programmable hydrogel actuator that combines rapid responsiveness, remote light-driven actuation, and intrinsic self-sensing capability. This study not only provides a paradigm for designing advanced tactile and self-sensing materials but also establishes a foundation for achieving closed-loop, remotely controlled soft actuators for next-generation intelligent mechanical systems.