Wide-Range Flexible Capacitive Pressure Sensors Based on Origami Structure

Abstract

In this paper, flexible pressure sensors based on 3D printing technology are presented. These flexible pressure sensors have different dielectrics and are designed to be a sandwich structure, which consists of a top electrode, flexible dielectric layer and a bottom electrode. The flexible dielectric layer in the middle is the pressure sensitive layer and is designed to be a hollow prism structure. This design is inspired by an origami structure and is intended to achieve excellent mechanical property. Besides that, in order to develop a method of improving flexible dielectric properties, an experiment of the synthetic composite dielectric layer is carried out and three kinds of flexible composite dielectrics are fabricated. Polydimethylsiloxane (PDMS), Barium Titanate (BaTiO ₃ ) and Carbon Nanotubes (CNTs) are used to synthesize composite dielectrics. They are PDMS compounded with BaTiO ₃ , PDMS compounded with CNTs, PDMS compounded with both BaTiO ₃ and CNTs, respectively. The dielectric structure is constructed with a 3D printed mold. The copper foil is patterned to work as electrodes of the sensors. Besides that, a sensor with pure PDMS dielectric is fabricated as a reference. By testing the sensitivity of these sensors, it was found that the sensor with dielectric made of PDMS doping both BaTiO ₃ and CNTs shows the highest sensitivity, which is about 0.1kPa ^-1 and 1.3 times of the reference sensor at the pressure below 20kPa. As a result, fabricating composite dielectric in this way can be a potential method to improve the device performance.