A Novel Capacitive-Based Flexible Pressure Sensor Based on Stretchable Composite Electrodes and a Dielectric Elastomer with Microstructures

This paper presents a novel capacitive-based flexible pressure sensor that achieves a relatively high sensitivity with an outstanding linearity over a large measurement range, as well as low-pressure detection capacity. The proposed sensor mainly consists of two flexible conductive composite electrodes and one micro-structured elastomer with both pillars and cavities. The highly stretchable modal fabrics and carbon nanotubes conductive paste have been proposed for mixture to generate flexible capacitor electrode plates, and provide improved attributes in terms of excellent flexibility, conductivity, and air permeability. The micro-structured elastomers have been proposed and fabricated via demolding the silicone poured into the high-precision patterns that are produced by the 3D printing techniques. The exerted compression on assembled sensor prototype can induce decreased distance between electrode plates and increased dielectric constant due to the air deflation, leading to enhanced sensor sensitivity. By comparing three types of microstructures for the elastomers, it is found that the cubic-structure type can achieve a high sensitivity (232∗10-4 kPa-1) with an excellent linearity of 99.4% in the measurement range of [0 kPa, 100 kPa]. The proposed flexible sensor has been prototyped, and several experiments have been performed for quantitative investigation and assessment. The grasp-and-release operations of a water-filled paper cup have been performed using a wearable glove embedded with two sensor prototypes, proving the effectiveness and feasibility of the proposed sensor design.