Nonlinear response in polymer optical fibre Bragg grating based sensors

Zhang, Wei; Webb, David J.; Peng, Gang-Ding

doi:10.1117/12.974937

Cited by 5 publications

(4 citation statements)

References 4 publications

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“…4a and 4b one can notice that POFBG wavelength change almost mirrors the water activity of the solution. In fact POFBG wavelength increases with the increment of water activity, but in a slightly nonlinear fashion, which is due to the nonlinear relation between PMMA swelling and water content inside PMMA optical fiber [11].…”

Section: Discussionmentioning

confidence: 97%

Polymer optical fiber grating as water activity sensor

Zhang

Webb

2014

SPIE Proceedings

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Controlling the water content within a product has long been required in the chemical processing, agriculture, food storage, paper manufacturing, semiconductor, pharmaceutical and fuel industries. The limitations of water content measurement as an indicator of safety and quality are attributed to differences in the strength with which water associates with other components in the product. Water activity indicates how tightly water is "bound," structurally or chemically, in products. Water absorption introduces changes in the volume and refractive index of poly(methyl methacrylate) PMMA. Therefore for a grating made in PMMA based optical fiber, its wavelength is an indicator of water absorption and PMMA thus can be used as a water activity sensor. In this work we have investigated the performance of a PMMA based optical fiber grating as a water activity sensor in sugar solution, saline solution and Jet A-1 aviation fuel. Samples of sugar solution with sugar concentration from 0 to 8%, saline solution with concentration from 0 to 22%, and dried (10ppm), ambient (39ppm) and wet (68ppm) aviation fuels were used in experiments. The corresponding water activities are measured as 1.0 to 0.99 for sugar solution, 1.0 to 0.86 for saline solution, and 0.15, 0.57 and 1.0 for the aviation fuel samples. The water content in the measured samples ranges from 100% (pure water) to 10 ppm (dried aviation fuel). The PMMA based optical fiber grating exhibits good sensitivity and consistent response, and Bragg wavelength shifts as large as 3.4 nm when the sensor is transferred from dry fuel to wet fuel.

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Section: Discussionmentioning

confidence: 97%

Polymer optical fiber grating as water activity sensor

Zhang

Webb

2014

SPIE Proceedings

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“…It is based on the fact that the wavelength response of a POFBG varies linearly with temperature/relative humidity at a fixed relative humidity/temperature. It has been reported that POFBG response exhibits nonlinearity [21]. This nonlinearity mainly arises from the mechanical responses of PMMA based optical fiber such as swelling and thermal expansion, which is closely related to the polymer fiber drawing process.…”

Section: Discussionmentioning

confidence: 99%

General Expression of Poly(Methyl Methacrylate) Optical Fiber Bragg Grating Sensing Response

Zhang

Webb

2019

IEEE Photon. Technol. Lett.

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Poly(methyl methacrylate) (PMMA) optical fiber inherently responds to the changes of temperature and relative humidity. PMMA optical fiber Bragg grating (POFBG) has been reported with diverse temperature and relative humidity sensitivities. These results cannot present the full performance of POFBG sensor as they are measured at limited environmental conditions. In this work we systematically investigated the POFBG temperature and relative humidity sensing responses. We found that POFBG temperature/relative humidity sensitivity is the function of both temperature and relative humidity. In the experiments POFBG sensing responses vary linearly with temperature/relative humidity at fixed relative humidity/temperature. Based on this linearity a general expression of POFBG sensing response to temperature and relative humidity has been obtained and verified for the first time, to describe the POFBG performance in desired operation range. The anisotropy in POF induced by drawing history could induce uncertainty in POFBG response but pre-straining POFBG overcomes this problem.

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“…Existance of the solute in the water will trigger the osmosis effect continuosly until a balanced condition achieved. Once the process stop, then the polymer fiber will start sensing the actual solution cocncentration [12]. The polished U-shape POF sensor had shown to have the highest responsivity with relatively higher linear responses compared to the polished coil-shape and tapered U-shape POF sensors.…”

Section: C) Polished Coil-shape Sensormentioning

confidence: 99%

High Sensitivity Optical POF Sensor for Detecting Low Ethanol Concentration in Water

Saad

Ali

Rahman

2015

AMR

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This paper presents the preparation of intensity-based plastic optical fiber (POF) sensor and its characteristics in the detection of ethanol concentration in water. Response of the sensor probes were analyzed for 0.02 to 1.00% v/v ethanol concentrations. The POF sensors have high sensitivity of detecting very low concentration of ethanol with 0.02% v/v ethanol in water. The reponsitivity of the polished U-shape sensor was 285 per percent of ethanol concentration. There are three distinct shapes of POF sensor probes that were developed: tapered U-shape; polished U-shape; and polished coil-shape. The POF were shaped into sensor probes by indirectly heating the POF at 80°C for several minutes and rapidly cooled in retaining the shapes. Tapering of POF was done using tensile tester with thermostatic chamber and other sensor probes were polished using fine abrasive for enhancing their sensitivities. The performance of the sensors was tested using He-Ne laser as the light source and the output spectra were analyzed using Ocean Optics spectrometer. The light intensity from the three sensors showed nonlinear response to ethanol concentrations from 0.02% - 1.00%. The POF sensor is more sensitive to 0.02%-0.10% ethanol concentration compared to 0.20% to 1.00%. At lower concentration, water tends to gradually absorb into POF polymer network and causes the fiber to swell more due to volume expansion. Higher ethanol concentration causes the swelling of the fiber to be eventually reduced and reached its detection limit.

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Nonlinear response in polymer optical fibre Bragg grating based sensors

Cited by 5 publications

References 4 publications

Polymer optical fiber grating as water activity sensor

Polymer optical fiber grating as water activity sensor

General Expression of Poly(Methyl Methacrylate) Optical Fiber Bragg Grating Sensing Response

High Sensitivity Optical POF Sensor for Detecting Low Ethanol Concentration in Water

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