Skin-Inspired Flexible Dual-Mode Tactile Sensor for Material and Hardness Perception

Inspired by the multireceptor collaborative perception mechanism of human skin, this study proposes a bio-inspired flexible dual-mode tactile sensor (SCTS). The sensor adopts a vertical integration strategy, combining triboelectric and capacitive pressure sensing modules into a compact thin-layer structure to simultaneously acquire material properties and pressure information. The triboelectric module, based on an electrospun polyvinylidene fluoride nanofiber membrane and laser-induced graphene electrodes, effectively captures dynamic contact signals, while the capacitive module utilizes the same electrodes with a polydimethylsiloxane dielectric layer to stably monitor static pressure. Tests demonstrate that the capacitive module achieves a detection range of 0–140 kPa with a maximum sensitivity of 0.4485 kPa –1, and the triboelectric module reliably discriminates eight common materials while maintaining consistent performance under varying pressures and frequencies. Integrated into an intelligent robotic hand system, the SCTS successfully accomplishes simultaneous identification of material type and object hardness, replicating the skin-like “fast and slow adaptation” collaborative perception mechanism. Through coordinated design of multilayer functional structures and optimization of materials and processes, this study provides a feasible approach to balancing device integration, sensitivity, and structural compactness in multimode tactile perception, demonstrating promising potential in the fields of electronic skin and intelligent robotics.