Laser-induced graphene/Cu-based fully-porous flexible capacitive pressure sensor with ultra-fast response and wide measurement range.

Recently, advances in human-machine interfaces have raised performance demands on flexible sensors. Achieving fast response, wide detection range, and high sensitivity remains a key challenge in flexible pressure sensor design. Here, we present a novel fully-porous flexible capacitive pressure sensor (FPFCPS) with a sandwich structure, comprising laser-induced Cu-composited graphene (LICuG) electrodes and a polyurethane foam dielectric layer modified with ionic liquid and coated with PVA hydrogel. The hierarchical porosity and conductivity of LICuG enable coupled mechanical interlocking and electronic polarization at the electrode-dielectric interface, improving interfacial contact, compressibility, and capacitive response. The sensor achieves a high sensitivity of 863.17 kPa⁻¹, a wide detection range (10 Pa-500 kPa), and a rapid response time of 5 ms, along with excellent flexibility and long-term stability. Notably, FPFCPS enables rapid tactile feedback and material recognition in dynamic robotic operations, offering high-resolution sensing in complex environments. This work represents the first application of LICuG in electric double-layer capacitance-pressure sensors and establishes a new structural design paradigm based on a fully porous architecture. It provides theoretical insights and practical strategies for advancing material development, mechanistic understanding, and implementation of intelligent sensing systems. In this study, femtosecond-laser-induced Cu-composited graphene (LICuG) was successfully synthesized. By incorporating this novel composite material into an electric double-layer capacitance sensing system, a fully-porous flexible capacitive pressure sensor (FPFCPS) was constructed. Through the synergistic regulation of the sensor's interlayer structural and electrical properties, its overall performance was significantly enhanced. When integrated at key robotic joints, the FPFCPS successfully detected collisions within ~5 ms and was capable of identifying the type of obstacle through tactile contact.