A high-sensitivity flexible piezoelectric tactile sensor utilizing an innovative rigid-in-soft structure

Piezoelectric tactile sensors are widely adopted to detect vibration and other stimuli. Among them, Polyvinylidene fluoride (PVDF) has the advantage of high flexibility, fast response and low cost. However, its sensitivity is restricted by the traditional d₃₃ working mode. Herein, we proposed a rigid-in-soft structure with truncated pyramid shape and soft bottom layer to enhance the force-transmission efficiency. This design synergizes the d₃₃ working mode and d₃₁ working mode, thereby surpassing the sensitivity limit. The mechanism has been analyzed using Finite Element Modeling (FEM), and experiment results indicate that rigid-in-soft tactile sensor exhibits a sensitivity of 35.6 mV/N, along with a linear force detection range of 1–11 N. The sensitivity is approximately 1.7 times higher than that of control sensor without rigid pillar. Furthermore, the sensor displays a great flexibility and reliability, making it highly promising for detecting dynamic stimuli in robotics, such as slip and vibration.