Intensity-based fiber optic pressure sensor with an Au/NiCr/Si3 N4/SiO2/Si3N4 diaphragm

Intensity based fiber optic pressure sensor has been fabricated using micromachining technology. The sensor consists of a multimode fiber bundle and a 100nm-Au/30nm- NiCr/150nm-Si3N4/300nm-SiO2/150nm- Si3N4 diaphragms supported by a micromachined frame-shape silicon substrate. The distance between the fiber bundle and the diaphragm of the pressure sensor is 900 micrometers . Three fiber optic pressure sensor having different size diaphragms were fabricated and used in experiments. The pressure sensitivities were 20.69 nW/kPa, 26.70 nW/kPa, and 39.33 nW/kPa for the pressure sensor with diaphragms of 3 X 3 mm2 area, 4 X 4 mm2 area, and 5 X 5 mm2 area.