Novel Structure and Characterization of Convex Touch Mode Capacitive Pressure Sensor (TMCPS) with Near Zero Touch Point Pressure (TPP)

In this paper, we present the structure and characteristics of a touch mode capacitive pressure sensor with a spherical substrate electrode with a touch point pressure (TPP) near zero pressure. The proposed touch mode capacitive pressure sensor consists of an elastic diaphragm-top moving electrode and a curved bottom fixed electrode that causes deformation under external pressure. The two electrodes are in touch before the external pressure is applied, and when the external pressure is applied, the upper moving diaphragm acts as a touch type, wrapping the bottom surface electrode from the beginning. In this paper, the capacitance-pressure output characteristics of the device are analyzed and compared with other touch point pressure sensors in the graphical state. With a given structural parameter, the effective operating pressure range of 0 ~ 1.75MPa was obtained, while the device capacitance was obtained in the range of 1.2×10-12 ~ 3.5×10-12F. This value is about twice as large as that of planar TMCPS. The effective operating pressure range are 0.18MPa larger compared to the TMCPS with no initial contact of the two electrodes at the same state and condition, since the TPP is near zero. The sensitivity and linearity are slightly different in the two structures.