Abstract
3D graphene-based flexible nanosponges have shown great application potential in areas such as human motion tracking, health monitoring, and electronic skin. However, previously reported graphene-based flexible sensors typically focus on simple pressure sensing, lacking the capability to simultaneously detect both pressure and physiological signals. This limitation restricts their application in the field of intelligent wearable technology. In this study, a pressure-flexible composite sponge sensor was prepared using polyvinylidene fluoride (PVDF), viscose nonwoven fabric, and graphene oxide (GO) in a simple and cost-effective manner. Results showed that high-pressure electrospun PVDF inhibited the α-crystalline phase while promoting the transformation of diffraction peaks into the β-crystalline phase. Furthermore, high-temperature oxidation–reduction improved the crystallinity of β-phase crystals, enhancing the conductivity of PVDF/reduced GO/viscose fiber/polydimethylsiloxane ( PV/rGO/VF/P )sponges. With the increase of GO mass ratio, the thermal stability of the flexible composite device improved while weight loss decreased and resistance sensitivity increased. When compressed to 40%, the piezoelectric effect is most sensitive, and the composite sponge can fully recover under 60% compression. The addition of viscose fiber with a high swelling effect enables the composite sponge to precisely and sensitively detect the amount of sweat or glucose. This three-dimensional nanosponge can be applied in the design of ergonomic, physiologically monitoring smart wearable devices.