Biologically imitated capacitive flexible sensor with ultrahigh sensitivity and ultralow detection limit based on frog leg structure composites via 3D printing

Inspired by the geometry of the frog leg, flexible capacitive pressure sensors utilizing a three-dimensional (3D) array of biomimetic frog-leg structure composites for use as dielectric layer is proposed. We demonstrate a low-cost and facile strategy to fabricate a dielectric layer with 3D features via 3D printing technique. The feasibility of using bionic frog-leg structure as a dielectric layer in capacitive pressure sensors is evaluated via finite element analysis (FEA). Several dimensional parameters of the dielectric layer structure were optimized via an experimental study of the pressure-sensing characteristics. The 3D dielectric structure reduces the Young's modulus of the dielectric layer and retains the stability of the sensor. The flexible capacitive pressure sensor exhibits improved sensing performance, including a broad pressure detection range (0–200 kPa), ultralow detection limit (0.5 Pa), ultrahigh sensitivity (0.583 kPa−1 in the range of 0–1.2 kPa), rapid response and recovery (40 ms and 45 ms at 1 kPa), and reliable long-term stability. This work is expected to open up possible applications in intelligent robots, wearable electronic devices, information perception, and human–machine interaction.