White-Light Interferometric Fiber Optic Liquid Level Sensor Based on MEMS Fabry-Perot Cavity

A novel white-light interferometric fiber-optic sensor based on fabry-Perot(F-P) cavity structure fabricated by the microelectromechanical systems (MEMS) technology for the measurement of the liquid level is presented. This fiber-optic sensor is especially sensitive to the pressure, and can detect the change of the pressure induced by the depth of liquid storage tanks. The construction of the sensor system is illuminated, and the sensing model is established by analyzing the detection mechanism of sensor. The sensor probe, a Fabry-Perot micro-cavity, is fabricated by MEMS technique and has a high sensitivity. The experiment system is established for evaluating the performance of the sensor fabricated. Test results show that the developed sensor system offers a sensitivity of 0.83 V/MPa within the pressure range of 0~6 MPa. Thus this sensor provides a practical way for the detection of the liquid level in the harsh environment which contains flammable materials or the risk of explosion.