Preparation and Pressure Sensitivity Extraction of Flexible MWCNT-PDMS Pressure Sensors

Flexible composite conductive materials have been widely used in the products of electronic skin, smart wearable devices, medical rehabilitation, and other fields due to their good electrical sensitivity and mechanical tension properties. In this work, multi-walled carbon nanotubes (MWCNT) were doped into Polydimethylsiloxane (PDMS) substrate to form piezoresistive microstructure, and the doping ratio was optimized. After the sample is prepared, its pressure sensitive property characterized by traditional resistance measurement is found to be much smaller than that of sensing materials. The decoration of sensitivity is proved to be induced by the high level of contact resistance. After applying the modified four-electrode method in the resistance measurement, the contact resistance and Schottky barrier introduced by the poor electrode contact are effectively eliminated, and the effective sensitivity of the sensing material reaches 0.038kPa
^-1
, which can satisfy the demand of electronic skin, wearable devices and high-precision medical testing. In addition, the results of this work also indicate that the methods to restrain the contact resistance, such as embedded electrodes, polishing the contact surface, increasing the contact area, and the optimization of electrode materials, can significantly improve the sensitivity of the flexible pressure sensor.