Flexible tactile sensor with high sensitivity utilizing botanical epidermal cell natural micro-structures

This paper presents and demonstrates the development of flexible tactile sensor utilizing the microstructures of onion epidermal cells, which replace the intermediate dielectric layer in a typical parallel-plate capacitive sensor. The onion epidermal cells can effectively reduce the complexity of the sensor structure and thus simplifies the device fabrication process. The single layer of the onion epidermal cells is robust for high tactile sensitivity, mechanical flexibility and optical transmittance with potentially low-cost sensor manufacturing in a large area. The 4 × 4 tactile sensor array with the total area of 20 × 20 mm² is demonstrated. A single tactile sensor has the initial capacitance of 9 pF without applying external pressure. The force ranging from 0 N-2 N (20kPa) is applied for sensor characterization. The sensitivity of the sensor is 0.14/kPa. The fabricated sensor shows high sensitivity and linearity. The proposed sensor array will be applied in robotic electronic skin and biomedical devices in the future.