Coplanar-Electrodes-Based Differential Structure for Piezoresistive Sensor Made of Carbon Nanotube Filled Silicone Rubber Composite

To develop the differential piezoresistive sensor made of carbon nanotube filled silicone rubber composite with concise configuration, a coplanar-electrodes-based differential structure is designed. The structure includes two composite films with high carbon nanotube content (12 vol.%) and two composite films with low carbon nanotube content (4 vol.%). All the electrodes for the four composite films are located in the same encapsulation layer (i.e., all the electrodes are located on the same side of the composite films), which can simplify the configuration of the sensor probe. The electrical resistance of the composite film with high/low carbon nanotube content decreases/increases with the increase of the compressive pressure and increases with the increase of the temperature. The two composite films with high carbon nanotube contents are placed on the two diagonal arms of an electrical bridge, and the other two composite films with low carbon nanotube contents are placed on the other two diagonal arms of the bridge. The experimental results verify the feasibility of using the coplanar-electrodes-based differential structure to reduce the output drift induced by the temperature and improve the sensitivity.