Studies On Fiber Optic Ph Sensors And Discussions About Their Industrial Application

The area of fiber optic pH sensor has bloomed since 1980's . It is a new analysis technology with high sensitivity, sequence , automatism and remote sense. The studies on fiber optic pH sensors focus on biological and medical viviperception. There are few dicussions about their industrial analytic application.Summarized the basic principle , present progress and the peculiarities of the method, five novel based on the hydrophobic indicators are synthesized and fiber optic pH sensors are manufactured.1. Neutral red hexadecyl imide is synthesized. A fiber optic pH sensor based on the hydrophobic indicators has been constructed by PVC investing method . It's response range is pH 7.0 - 9.0 with a response time of 20 sec. The described sensor has a good reversibility, stability and selectivity. In addition, the possibility of the sensor applied at high temperature is described here. At 70 癈 , it also keeps excellent reversibility stability and selectivity.2. Gallein hexadecyl ester is synthesized. A fiber optic pH sensor based on the hydrophobic indicators has been constructed. It's response range is pH 7.0 - 9.0 with a response time of 87 sec. The described sensor has a good reversibility, stability and selectivity. At 80 癈, it also keeps excellent reversibility stability and selectivity.3. Rosolic acid hexadecyl ester is synthesized. A fiber optic pH sensor based on the hydrophobic indicators has been constructed. It's response range is pH 9.0 - 10.5 with a response time of 80 sec .The described sensor has a good reversibility, stability and selectivity. At 70℃, it also keeps excellent reversibility stability and selectivity.4. Bromothymol blue hexadecyl ester is synthesized. A fiber optic pH sensor based on the hydrophobic indicators has been constructed. It's response range is pH 8.5 - 10.5 with a response time of 65 sec .The described sensor has a good reversibility stability and selectivity. At 70 C, it also keeps excellent reversibility stability and selectivity.5. Bromophenol Blue hexadecyl ester is synthesized. A fiber optic pH sensor based on the hydrophobic indicators has been constructed. It's response range is pH 6.5 - 8.0 with a response time of 82sec. The described sensor has a good reversibility stability and selectivity. At 80℃, it also keeps excellent reversibility, stability and selectivity.In this paper, a fiber optic pH sensor with gallein hexadecyl ester as representative sample, the span life in cane sugar clear juice (at 60℃)and the deposit question are discussed. The results show the respond signal does not attenuate and no deposit on the sensing film within 21 days.