Modeling and Development of a Flexible Carbon Black-Based Capacitive Strain Sensor

The wide range of applications of strain sensors leads to an increased interest on flexible, cost effective, and low-power devices for strain and bending measurements. A simply structured sensor that meets these requirements is studied using a finite-element analysis. The sensor design focuses on the sensor performance variations for different applications and takes into account the fabrication process that can be used for elastomeric flexible sensors. Both large and small strain performance is considered. The simulation results are also compared with experimental measurements exploiting a flexible parallel plate capacitive strain sensor comprising carbon black-polydimethylsiloxane (PDMS) composite layers as electrodes and PDMS as the dielectric and encapsulation material. A simple and low-cost fabrication process was used, and the sensor was tested in a cantilever beam measurement setup. The device exhibits linear capacitive response (R-2 = 0.999) and gauge factor 1.45 for small strain changes.