Preparation And Research Of The Sensing Materials Based On Highly Elastic Three-dimensional Graphene Composites

With the advent of the 5G era,wearable stress/strain sensing has great application requirements in fields such as artificial intelligence devices,electronic skin,and human health monitoring.In recent years,the development of stress/strain sensing materials with wide range,high sensitivity and good stability has gradually become a research hotspot.The highly elastic three-dimensional graphene composite material presents a unique three-dimensional spatial structure.This three-dimensional network skeleton can provide a continuous conductive channel.The resistivity of the material changes due to the change of the contact area of the conductive skeleton during the compression/recovery process.In turn,an electrical signal sensor response is generated.The currently prepared high-elastic three-dimensional graphene composite sensing material has a complicated preparation process,and its mechanical properties and sensing properties often cannot reach the ideal state at the same time.In this paper,a low-cost,easily available,highly elastic polyurethane sponge is used as the skeleton material,and graphene and other materials are loaded in the sponge through simple solution dipping and self-assembly processes to improve the sensitivity and stability of the sensing material.The research of this paper mainly includes:（1）Load graphene oxide on the polyurethane sponge skeleton by solution immersion method,and reduce with hydrogen iodide to obtain a three-dimensional conductive network based on the polyurethane sponge,and further form a large-scale reduced graphene oxide structure between the three-dimensional skeletons by a self-assembly method.The microscopic morphology characterization shows that the reduced graphene oxide sheet layer can be uniformly loaded on and between the polyurethane framework,and its three-dimensional continuous structure can be better maintained during the compression/recovery process.The sensing performance test shows that the stress/strain and the resistivity change present a multi-segment linear response,the strain sensing range is 0～80%,and the sensitivity is up to 1.73;the stress sensing range is 0～30 k Pa,and the sensitivity is up to 0.072 k Pa^-1.1000 compression cycles under 80%strain,the resistance change rate can still reach 80%.Corresponding resistance changes can be detected in the arm,elbow,finger,knee diastolic and bent state.（2）Polyurethane-graphene was loaded onto the polyurethane sponge framework by solution impregnation.The polyurethane can act as an adhesive and enhance the adhesion of the graphene sheets to the sponge framework,improving the structural stability of the conducting network in the compression/recovery process.The micro-morphology shows that polyurethane can be uniformly distributed between the graphene sheets.The sensor performance test shows a multi-segment linear response in the strain range of 0～80%and the stress range of 0～45 k Pa.After 1000 compression cycles under 80%strain,the resistance change rate can reach 88%.In the process of body movement monitoring,the electric signal change of body movement can be feedback in real time.