A High-Sensitive Rubber-Based Sensor with Integrated Strain and Humidity Responses Enabled by Bionic Gradient Structure

Real-time detection of different physiological characteristics is crucial for human physical and mental health. A detection system with multimodal sensing capability, high sensitivity, excellent mechanical properties, and environmental stability is highly desirable, but it is still a great challenge. Inspired by the structural gradient of biological tissues, a multifunctional sensor based on carboxylic styrene butadiene rubber (XSBR) and sodium polyacrylate (PAANa) non-covalently modified MXenes is prepared in this study, in which the MXenes exhibit a gradient distribution and simultaneously formed an orientation arrangement at the bottom of the matrix through the formation of hydrogen bonding interactions with PAANa. The material shows a considerable stretchability of 244% and strength of 7.67 MPa, high electrical conductivity of 55.40 S m-1, low percolation threshold of 2.48 wt%, and excellent response to strain (gauge factor of 906.7 within 98% strain) and humidity (relative resistance change of 530% within 11-93% relative humidity). Based on the superior performances of the XSBR/PAANa/MXene composite, an integrated detection system is designed to accurately detect respiration and body movements at various scales. This work provides a new perspective for the development of a novel biomimetic functional material for sensor applications. Inspired by the gradient structure from the dry bracts, a novel carboxylic styrene butadiene rubber (XSBR)/sodium polyacrylate (PAANa)/MXene composite is designed, in which the MXenes are gradient-distributed from one side to the other. The composite exhibits an excellent response to strain (gauge factor of 906.7 within 98% strain) and humidity (relative resistance change of 530% within 11-93% relative humidity), simultaneously. image