Performance Study of Flexible Capacitive Pressure Sensor Based on Dielectric Structures

In recent years, with the emergence of the flexible electronic devices for artificial skin, wearable electronics, robotics, etc., more and more attention has been paid to the flexible force sensor. In this study, we designed and fabricated a flexible capacitive pressure sensor with unique washer structure and dielectric layer microstructure. The sensor consists of the flexible substrate, main dielectric and the electrode materials, using polyethylene terephthalate (PET) film, the air and the silver nanoparticles (AgNPs), respectively. Then, we systematically investigated the effect of the thickness of the washer and dielectric layer microstructure on the performance of the flexible capacitive pressure sensor. It shows that the thinner the thickness of the washer, the better the sensitivity of the sensor. However, it might lead to the degraded performance in terms of the repeatability and the stability. Besides, the dielectric layer microstructure has also a significant effect on the performance of the sensor. Furthermore, the sensitivity of the single-layer microstructure sensor is superior to those of the double-layer microstructure and no-microstructures. In respect of the stability and the repeatability of the sensor, double-layer microstructure sensor is best, followed by the single-layer microstructure and the no-microstructure. In summary, the highest sensitivity of the sensor we fabricated is 0.17 kPa(-1), and the minimum detectable pressure is several pF. It has a large dynamic range and stable performance. Thus, our sensor can be widely used in many applications in the emerging fields of medical testing equipment and robotics.