Simulation based design and fabrication of a PPy coated PDMS based pressure sensor

Official URL: https://drive.google.com/file/d/1hxxaEshJ1JoI3JFjDE2Nt8IndaTi0JS-/view

Flexible sensors have attracted widespread attention because of their highly desired multifunctionality such as flexibility, high sensitivity, and large workable range in electronic skin or wearable health monitoring applications. Among these, piezoresistive pressure sensors are expected to deliver these functions in a stable fashion whilst being produced in a low cost and scalable manner. It is known that sensor performance directly depends on the 3D geometrical and material composition. In this study a flexible pressure sensor with a unique interconnected and porous geometry is designed and fabricated using a simulation based design approach and a two-step manufacturing technique. The substrate of the sensor is cast using Poly- dimethylsiloxane (PDMS) which is known for its mold-release properties and ability to replicate fine features with low shrinkage and excellent elastic properties. The 3D PDMS structures were prepared by mixing base solution and curing agent at a weight ratio of 10:1 following poured onto 3D printed molds and cured at 80 °C for over 2 h. The sensing capability of the composite material was achieved by the facile solution based dip coating method of polypyrrole (PPy) thin film onto the PDMS structure. The mechanical and electrical response of the proposed PPy coated PDMS sensor was characterized using compression tests via a multimeter setup integrated to Universal Testing Machine and a four-point probe measurement system. Micro-computed tomography characterizations were used to analyze the cast sensor’s geometrical features. Simulations were carried out using Finite Element Analysis software COMSOL Multiphysics. Both simulations and measurements demonstrate that the proposed sensor delivers a stable piezoresistive behavior with high sensitivity. The proposed production technique’s flexibility to produce sensors with complex 3D geometries combined with the tuning potential of the sensor’s sensitivity should prove useful for a wide range of applications with different desired pressure ranges.