Flexible capacitive pressure sensors fabricated by 3D printed mould

Abstract

In this Letter, flexible capacitive pressure sensors are developed. Compared to the current mainstream design, the structure is easier to get a large deformation in the dielectric layer and its deformation is more controllable. Since the structure is symmetrical, it deforms uniformly and its Poisson's ratio is near zero when pressure is applied. Besides that, by moderating the structure dimension, sensors with different sensitivity and detection pressure range can be achieved. The fabrication process of these flexible sensors is mainly based on the 3D printing technology, with which the moulds of the sensor are made. The mixture of polydimethylsiloxane and hardening solution is dripped into the printed mould to form the dielectric layer. When it is completely solidified, the dielectric layer is demoulded from the mould. Four moulds with different inner sizes are printed and then four sensors are fabricated and tested. The measurement results show that the capacitance of the sensors increases when the applied pressure increases. The sensor with thinner supporting structure in the dielectric layer has higher sensitivity. The sensor with a thicker supporting structure in the dielectric layer has a larger pressure detection range. All the sensors have low hysteresis error and excellent repeatable performance.