Investigating capacitive flexible tactile sensor with a wide measuring range using PVDF and conductive sponge

Abstract

Flexible tactile sensors have important application value in the field of artificial intelligence and Internet of Things. At present, it is a great challenge for tactile sensors to maintain high sensitivity and stability in a large pressure range. This article proposes a flexible capacitive tactile sensor with high sensitivity and large measuring range, which has a sandwich structure. The purpose of this paper is to determine the relationship between the thickness, surface microstructure, sensitivity, and sensing range of PVDF films. The sensor uses conductive sponge with a microstructure surface and an ultra-thin PVDF film as the electrode and dielectric layer, respectively, and provides a comprehensive study in terms of sensor design, theoretical calculation, computer simulation and applications. The minimum detection limit of the sensor are tested by sound vibration, needle blowing, and human physiological signals. It has been shown that the thicker the PVDF film, the lower the sensitivity and the wider the sensing range. The proposed sensor can accurately identify physiological signals such as respiration, pulse and swallowing, and can perceive the softness, hardness and weight of the object as well as identifying the grasping posture. Moreover, the sensor has the characteristics of short response time, good recoverability and stability.