MEMS capacitive pressure sensor array fabricated using printed circuit processing techniques

Abstract

Micro electro-mechanical systems (MEMS) based capacitive pressure sensors are typically fabricated using silicon micromachining techniques. In this paper, novel liquid crystal polymer (LCP) based capacitive pressure sensors, fabricated using printed circuit processing techniques, are reported. LCP exhibits good dimensional stability, material flexibility, high chemical resistance, and extremely low moisture absorption, which makes it suitable for MEMS applications. The pressure sensor comprises of a cylindrical cavity formed by a sandwich of LCP substrate, LCP spacer layer with circular holes and LCP top layer. The bottom electrode and the top electrode of the capacitive pressure sensor are defined on the top surface of the LCP substrate and the bottom surface of the top LCP layer, respectively. A typical pressure sensor with a diaphragm diameter of 3.2 mm provides a total capacitance change of 0.7627 pF for an applied pressure in the range of 0-170 kPa.