Non-invasive capacitive pressure sensor: Microfabrication process and first electro-mechanical characterization

Kapton-based flexible pressure sensor arrays are fabricated using a new technology of film transfer. The sensors are dedicated to the non-invasive measurement of pressure/force in robotic, sport and medical applications. The sensors are of a capacitive type, and composed of two millimetric copper electrodes, separated by a polydimethylsiloxane (PDMS) deformable dielectric layer. On the flexible arrays, a very small curvature radius is possible without any damage to the sensors. The inhomogeneity of the capacitances in array is quite low (deviation of ±7% compared to the average value). The process is accurate and reproducible (transfer yield of 100%). The electrical characterization is also presented. In the preliminary electro-mechanical characterization, a sensor (with a PDMS dielectric layer of 660 μm thickness and a free load capacitance of 480 fF) undergoes a capacitance change of 17% under a 300 kPa normal stress.