Highly Sensitive Fiber Optic Pressure Sensor Based on Silica Diaphragm Fabricated by MEMS

Abstract

This paper presents the fabrication procedure of a 1.2-μm thick silica diaphragm with high uniformity using microelectromechanical systems (MEMS) technique. The diaphragm fabrication started from a commercially available double-polished 300-μm silicon wafer with a silica layer on its bottom. The silica diaphragm was released from the wafer by photolithography, wet etching and inductively coupled plasma (ICP) etching. A fiber optic Fabry-Perot (FP) pressure sensor was made by thermally bonding the diaphragm to the end face of an etched fiber with an outside diameter of 125 μm. The obtained sensor has a static pressure sensitivity of 12.4 nm/kPa (85.3 nm/psi). It has a great potential to work in medical applications where miniature size and high sensitivity are essential.