Preliminary Study Of Chemical Sensor Based On Porous Fiber-Optic

Fiber-optic chemical technique is a new field which combines multidisciplinary. It takes thefiber as a medium; the ray focusing into the optical fiber in the sample to acquire real-timeinformation to the analyte, then completes the sensing after signal processing to obtain On-line,continuous, in situ analysis in the biological, chemical and environmental fields. Microstructuredoptical fiber is widely used in the field of chemical and biological Sensing, the array pore runthrough the entire volume provides a good place for trace detection of biochemical reactions.The new fiber offers the possibility preparing a new generation chemical and biological sensorswhich are integrated, high sensitivity, and miniaturization.In this paper，combining the structural characteristics of microstructure fibers, a new type ofoptical fiber sensing probe based on this fiber is prepared. The modification techniques is carriedout in the array holes of the microstructured polymer optical fiber and some relevant objects areselected to do characteristics experiment of the sensing performance. This paper includes threeareas: preparation and properties of ammonia sensing probe modified with eosin-doped sensitivefilm; preparation and properties of oxygen sensing probe modified with [Ru（dpp）3]cl2dopedsensitive film; preparation and properties of fluride sensing probe modified with Morin-Al orAlQ3doped sensitive film.（1）: Ammonia sensing uses eosin as indicator and doped it in cellulose acetate or sol-gelfilm. Polymer solution doped with eosin is directly inhaled into array holes of MPOF and thenthe probes are prepared. The sensing probe showed different fluorescence intensity at576nm todifferent concentration of trace ammonia in carrier gas of nitrogen.The linear response range was140-400ppm, with short response time within500ms.（2）: Oxygen sensing use [Ru（dpp）3]cl2or TPP as indicator and doped it in celluloseacetate or sol-gel film. Polymer solution doped with indicator was directly inhaled into18arrayholes of MPOF at negative pressure. We produced three kind of sensing probes, includingTPP-CA,[Ru（dpp）3]²⁺-CA, and [Ru（dpp）3]²⁺-Gel. Comparing the properties of the probe showedthe sensitivity of the I0/I was1.51,2.81,10.8respectively. Simultaneously, the optrode can makea quick response within50ms and the response curve is approximately linear in the range of0%to100%.（3）: Floride sensing uses Morin-Al or AlQ3as indicator. Two optical fluoride probes are fabricated based on Microstructured Polymer Optical modified by indicator doped in sol-gel orPVC film. The sensing probe shows different fluorescence intensities to different fluoride ionconcentrations in the aqueous solution. To sum up, Morin-Al-MPOF probe is better thanAlQ3-MPOF probe in general properties. Morin-Al-MPOF probe has good response at buffersystem which pH at4.6, the linear response range is5-50mmol/L and the response time is160ms.Now the modified technology in the holes of microstructure fiber and the preparationresearch of chemical sensors are a new resrarch field. The modified technology in internal arrayof MPOF pore surface which our subject developed has a wider application prospects in thebiological sensing and environmental monitoring.