Liquid crystal polymer based MEMS capacitive pressure sensor

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 make it suitable for MEMS applications. Each sensor consists of an LCP substrate, an LCP spacer layer with circular holes, and top LCP layer. The portion of the top LCP layer located above the circular hole of the spacer layer serves as the circular diaphragm of the pressure sensor. A typical pressure sensor with a diaphragm radius of 1.6 mm provides a net capacitance change of 0.18 pF for an applied pressure in the range of 0-70 kPa. Hundreds of such sensors can be batch fabricated cost effectively using existing flexible printed circuit technology.