Simultaneous Measurement of Liquid Level and Specific Gravity Based on Optical Fiber Sensors

• Main Authors: Chih-Wei Lai, 賴志瑋
• Other Authors: Yu-Lung Lo
• Format: Others
• Language: en_US
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/89572034487602688822

碩士 === 國立成功大學 === 奈米科技暨微系統工程研究所 === 97 === In this study, the optical fiber liquid level sensor based on fiber Bragg grating and the optical fiber pressure sensor based on Faby-Perot interferometer have been designed and fabricated. The liquid level sensor makes use of the fiber Bragg grating that glued onto the centric surface of uniform strength cantilever beam. The liquid level sensor can measure the range from 0.45m to 0.78m with the sensitivity of 0.01491nm/cm and it exhibits an approximately linear response. The design and fabrication of the pressure sensor based on Fabry-Perot interferometer utilize the MEMS technique and only needs a few of simple procedures. The pressure sensing membrane consists of a base polyimide layer, a metal reflective layer, and a SU-8 layer covered on the metal layer. The measurement range of the pressure sensor is from 0.98kPa to 6.86kPa with the sensitivity of 0.1569μm/kPa. The simultaneous measurement systems of liquid level and specific gravity have also developed in this study. Any two sensor elements in this thesis can be combined to a simultaneous measurement system of liquid level and specific gravity. The system can reduce the error to minimum by way of calibration of the sensor elements. The average errors of these systems for specific gravity are 0.0153, 0.0247 and 0.0357, respectively. And the average errors of these systems for liquid level are 0.0120m, 0.0144m and 0.0273m, respectively.