Reducing the Influence of the Contact Area on a Soft Capacitive Force Sensor

In this study, the influence of the contact area on measurements by a soft capacitive force sensor was analyzed. Based on the results, a method for selecting a dielectric material to reduce the contact area influence on the sensor is proposed. First, the soft capacitive force sensor was approximated as a discrete model, which was used to analyze the relationship between the capacitance of the sensor, applied force, and contact area. This relationship was used to derive a stress-strain curve for a dielectric that can remove the contact area influence, which was defined as the ideal curve. The proposed method uses the ideal curve to evaluate dielectrics for whether they can decrease the contact area influence. Experiments confirmed that the proposed method can be used to fabricate a soft force sensor with a small contact area influence.