Optical Waveguide BTX Gas Sensor Based on Yttrium-Doped Lithium Iron Phosphate Thin Film

Patima Nizamidin,Ismayil Nurulla,Abliz Yimit,Kiminori Itoh

doi:10.5402/2012/606317

Patima Nizamidin, Ismayil Nurulla + Show 2 more

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https://doi.org/10.5402/2012/606317

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Abstract

Yttrium-doped LiFePO4 powder was synthesized using the hydrothermal method in one step and was used as a sensing material. An optical waveguide (OWG) sensor based on Yttrium-doped LiFePO4 has been developed by spin coating a thin film of LiFe0.99Y0.01PO4 onto a single-mode Tin-diffused glass optical waveguide. Light was coupled into and out of glass OWG employed by a pair of prisms. The guided wave transmits in waveguide layer and passes through the film as an evanescent wave. The sensing film is stable in air, but when exposed to target gas at room temperature, its optical properties such as transmittance (T) and refractive index (nf) were changed; thus, the transmitted light intensity was changed. The LiFe0.99Y0.01PO4 thin film OWG exhibits reversible response to xylene gas in the range of 0.1–1000 ppm. When the concentration of BTX gases was lower than 1ppm, other substances caused a little interference with the detection of xylene vapor. Compared to pure LiFePO4 thin film OWG, this sensor exhibited higher sensitivity to BTXs.

Highlights

Benzene, toluene, and xylene (BTX) are volatile organic compounds (VOCs) of great social and environmental significance, are widely used in industry, and can present serious medical, environmental, and explosion dangers [1]
We describe the fabrication of the LiFe0.99Y0.01PO4 film/Tin-diffused glass optical waveguide sensor, and we use this OWG sensor system which successfully detected 0.1 ppm (100 ppb) of xylene gas as an example of BTX
We have found that the LiFe0.99Y0.01PO4 film refractive index and thickness for the OWG BTX gas sensor were 1.899 and 104 nm, respectively

Summary

Introduction

Toluene, and xylene (BTX) are volatile organic compounds (VOCs) of great social and environmental significance, are widely used in industry, and can present serious medical, environmental, and explosion dangers [1]. The optical waveguide (OWG) sensors [7,8,9] are small in size, of high sensitivity, of fast response time, monitored at room temperature, and of intrinsically safe detection. They suffer little or no interference in the waveguide element of the sensor and can be made at a very low cost. We describe the fabrication of the LiFe0.99Y0.01PO4 film/Tin-diffused glass optical waveguide sensor, and we use this OWG sensor system which successfully detected 0.1 ppm (100 ppb) of xylene gas as an example of BTX

Experimental Section

Results and Discussion

Conclusion