Modeling and Analysis of a Flexible Capacitive Tactile Sensor Array for Normal Force Measurement

This paper presents an analytical model to analyze the flexible capacitive tactile sensor array for normal force measurement. The tactile sensor array consists of six layers, including a bottom polyethylene terephthalate film, a lower copper plate, a polydimethylsiloxane film, an upper copper plate, a polyimide (PI) film, and a top PI bump, respectively. By simplifying the sensing unit into a two-layer structure, an analytical model is developed to study the normal force prediction. Finite element modeling (FEM) is conducted to analyze the deformation of the sensing unit, and is compared with the analytical model. Results show that analytical model predicted deformation matches well with the FEM analysis. The change of capacitance verse normal force is obtained, and can be utilized for accurate normal force measurement. Based on the established analytical model, the behaviors of the proposed sensor are analyzed by applying uneven force and shear force.