Preparation of multi-axial compressible 3D PVDF nanofibre/graphene wearable composites sensor sponge and application of integrated sensor

Compared with piezoelectric and capacitive sensor devices, piezoresistive sensor devices have a simple preparation process and good sensing performance, and are the most widely used in flexible strain sensing. The sensing performance of piezoresistive flexible strain sensors is usually characterized by parameters such as sensitivity, sensing range and durability. The development of piezoresistive sensor devices with multiple excellent properties at the same time is the current research hotspot. In this study, a PVDF nanofibre/graphene multiaxial compressible composites sponge sensor was prepared by combining nanotechnology with a freeze-drying method, and then integrated bridge circuit devices through multiple sensing sponges. The sensor device prepared in this study is a multifunctional wearable device with high sensitivity, wide sensing range and good durability. Results show that the addition of excessive graphene significantly improves the pore morphology, in which it is a cube porous with a uniform size. The thicker porous wall formed by the entanglement of graphene sheets improves the mechanical strength of the sensor. The sponge sensor also has excellent elasticity, whilst the elastic recovery rate can be as high as 90% when the compression reaches more than 80%. When compressed in different directions, it has a wide sensing range, whilst the resistance change rate can be from 110% to 0.5%, all of which are regular wave curves. The bridge circuit integrated device of multiple sensing sponges obviously improves the overall sensitivity of the sensor under the same compression ratio, the compression ratio is reduced and the service life is increased. This conclusion lays a research foundation for the application of multi-module piezoresistive sensor integration in the field of smart wearables.