An MEMS optical fiber pressure sensor fabricated by Au-Au thermal-compression bonding

In this paper, an optical fiber Fabry-Perot (F-P) pressure sensor based on micro-electro-mechanical system (MEMS) techniques is presented. We use SOI wafer and Pyrex glass wafer with micro-circular shallow pit array to fabricate the sealed F-P cavity structure by employing Au-Au thermal-compression bonding technique which avoids the gas releasing due to chemical reaction during anodic bonding process. The loaded pressure on the silicon diaphragm is transferred to cavity length information and measured by using polarization low-coherence interference demodulator. The response range and sensitivity of this pressure sensor can be simply altered by adjusting the parameters of radius and thickness of silicon diaphragm. This batch fabrication process is helpful for keeping performance consistency of the sensors. Fabrication and experimental investigation of the sensors are described. Results show that the sensor exhibits a relatively linear response within the pressure variation range of 3-283kPa with a sensitivity of 23.63 nm/kPa and the repeatability of the sensor is about 0.119%F.S. Additionally, the temperature dependency is approximately linear with 1.7nm/degrees C from -20 degrees C to 70 degrees C.