Tactile Sensor for Texture Recognition Based on a Piezoelectric Microdome Array

E-skins integrated with dense, conformal arrays of tactile sensors are pivotal to bridging the perception gap between the robots and the physical world. Piezoelectric tactile sensors typically exhibit wide dynamic range and large bandwidth, making them excel at collecting rich transient and dynamic information based on touch for material and texture recognition. Here we report a flexible tactile sensor based on an array of micro-scale piezoelectric domes for texture recognition. The dome array is vacuumembossed on a polyvinylidene fluoride (PVDF) film. Soft UV-curable adhesives underfill the domes to achieve good physical integrity and stable performance. The protruded microstructures enable a$12 \text{mm} \times 12 \text{mm}$device to exhibit over$5 \text{mV} / \mathrm{N}$and$1.5 \text{mV} / \mathrm{N}$sensitivities under normal and shear forces, respectively, from 20 Hz to 500 Hz. The outstanding dynamic behavior of the device enables perception of subtle variations at the contact interface when it slides on different surfaces. An average accuracy of 96.17 % is achieved by the proposed device for texture recognition across six different fabrics. Such flexible tactile sensors can be scaled to large area at low cost, and exhibit significant potentials as e-skins for humanoid robots and haptic interfaces for virtual or augmented reality.