A SOL-GEL BASED FIBER OPTIC SENSOR FOR pH MEASUREMENT

• Main Authors: Ming-Che Hung, 洪明哲
• Other Authors: Woo-Hu Tsai
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/mdr55w

碩士 === 大同大學 === 光電工程研究所 === 95 === In this thesis, we have fabricated a novel side-polished fiber sensor for pH measurement. To utilize the structure to measure the variation of the pH in the acid or base solution, we measure the signal by the particular wavelength was absorbed to change the spectrum within the side-polished or the grating region. To increase the sensitivity of the sensor, we polish the surface of the fiber into the core region which have a good Evanescent-wave response ,and then a long period grating surface was also made on the side-polished surface by virtue of ICP RIE technique. The comparison of both side-polished and long period grating fiber sensors have been carried out. Beside, we introduced a sol-gel method to synthesize the sensing film (including three indicators such as cresol red, bromophenol blue and chlorophenol red) on the polished surface of the fiber pH concentration measurement. The light sources (halogen light, 690nm laser, 1537.86nm laser) were used to define the light into the fiber sensor to sensing the range of pH concentration. It identification the pH value change from 2.4 to 11.2 can be measured by the sensor we proposed. Moreover, small size and easy fabrication are the advantages of the sensors. The experimental results haveing very good pH response from strong acid to strong base.