High-Sensitivity Carbon Nanofibers/Graphene/Polydimethylsiloxane Flexible Pressure Sensor Based on a Hierarchical Structure with Enhanced Sensing Range

Achieving a high sensitivity of sensors over a wide linear range is crucial for practical applications. Introducing various micronano topologies is the most effective approach to enhance sensor sensitivity. Unfortunately, due to the size effect, the surface structure is prone to deformation and saturation under pressure, limiting sensitivity to a narrow range and hindering broader applications. Additionally, few of the recently developed sensors with wide sensing ranges have been able to achieve the high sensitivity levels provided by micronano topological structures. The achievement of an effective trade-off between high sensitivity and a wide sensing range still presents significant challenges. In this study, a versatile strategy is proposed to design a high-sensitivity flexible pressure sensor with an improved sensing range. A cost-effective and adjustable wire mesh is utilized to introduce microstructures while constructing a hierarchically reinforced structure, effectively combining porous and surface microstructures. Hybrid carbon nanofibers and graphene serve as conductive materials to further enhance the performance. The sensor demonstrates a high sensitivity of −1.12 kPa–1 and extends the sensing range to nearly 3.9 times (0–853 Pa) compared to sensors with only microstructures (0–220 Pa). Moreover, it exhibits a response speed comparable to that of the human body (26 and 33 ms) and a high durability (4000 cycles). The sensor showcases excellent signal response to high-pressure movements (finger bending and wrist bending) and low-pressure breathing movements, holding promising potential for motion monitoring and information encryption applications.