Abstract
As global warming and climate change persistently threaten our planet, especially in developing countries, environmental monitoring becomes more and more imperative. One of the key parameters in estimating ecological disturbance due to climate change is temperature. In this work, we design a temperature sensor based on a fiber Bragg grating (FBG) and investigate the effect on its sensitivity upon applying a polymeric coating, and contrast it with different metal coatings. The reflected spectrum of an FBG has a narrow peak, corresponding to the Bragg wavelength, which is contingent on the grating period, grating length and effective refractive index. We simulate an outdoor ambient environment and examine the change in the peak reflected wavelength on variation in temperature. The shift in the peak for a unit change in temperature can be defined as the sensitivity of the FBG sensor. To enhance the sensitivity, we apply a uniform coating of Polytetrafluoroethylene (PTFE), more popularly known as Teflon. We also compare the sensitivity obtained on using PTFE coating with that through other materials, such as zinc, aluminum and stainless steel. It is visibly evident from this assessment that the coefficient of thermal expansion (CTE) has a significant effect on the sensitivity, when other physical and mechanical parameters are maintained constant. Since the CTE value is much higher for polymers than it is for metals, PTFE is able to provide a sensitivity of 0.3 nm/ °C, which is impressive when compared to zinc, the metal offering the highest sensitivity of around 0.079 nm/ °C. However, the CTE of PTFE itself varies with temperature, which is why we predict a sudden nonlinearity in the temperature dependence of the reflected wavelength, in an experimental scenario. Investigating this deviation leads us to the conclusion that, in the temperature range of 19–25 °C, PTFE undergoes two phase transitions from a triclinic to a hexagonal crystal phase, and subsequently to a pseudo-hexagonal phase. We calculate the sensitivities for the various phases of PTFE, and conclude that the high numerical and simulated values make this technology a promising application for futuristic purely optical sensors.
Similar content being viewed by others
References
Angevine, W. M. (2000). Radio acoustic sounding system (RASS) applications and limitations. In: IEEE 2000 international geoscience and remote sensing symposium (IGARSS). https://doi.org/10.1109/IGARSS.2000.858060.
De Miguel-Soto, V., et al. (2017). Study of optical fiber sensors for cryogenic temperature measurements. Sensors. https://doi.org/10.3390/s17122773.
De Lima Filho, E. S., Baiad, M. D., Gagne, M., & Kashyap, R. (2014). Fiber bragg gratings for low-temperature measurement. Optics Express,22(22), 27681–27694.
Alvarez-Botero, G., Baron, F. E., Cano, C. C., Sosa, O., & Varon, M. (2017). Optical sensing using fiber Bragg gratings: Fundamentals and applications. IEEE Instrumentation and Measurement Magazine,20(2), 33–38.
Chan, T. H. T., et al. (2006). Fiber bragg grating sensors for structural health monitoring of Tsing Ma bridge: Background and experimental observation. Engineering Structures,28(5), 648–659.
Hung, Y. J., et al. (2017). Narrowband silicon waveguide Bragg reflector achieved by highly ordered graphene oxide gratings. Optics Letters,42(22), 4768–4771.
Al-Fakih, E. A., Osman, N. A. A., Eshraghi, A., & Adikan, F. R. M. (2013). The capability of fiber bragg grating sensors to measure amputees’ trans-tibial stump/socket interface pressures. Sensors,13, 10348–10357.
Huang, J. Y., et al. (2017). FBGs written in specialty fiber for high pressure/high temperature measurement. Optics Express,25(15), 17936–17947.
Wang, J. N., & Tang, J. L. (2010). Feasibility of fiber bragg grating and long period fiber grating sensors under different environmental conditions. Sensors,10(11), 10105–10127.
Ma, G. M., Li, C. R., Mu, R. D., Jiang, J., & Luo, Y. T. (2014). Fiber Bragg grating sensor for hydrogen detection in power transformers. IEEE Transactions on Dielectrics and Electric Insulation,21(1), 380–385.
Ahmed, F., Ahsani, V., Saad, A., & Jun, M. B. (2016). Bragg grating embedded in Mach–Zehnder interferometer for refractive index and temperature sensing. IEEE Photonics Technology Letters,28(18), 1968–1971.
Cheng, L., Steckl, A. J., & Scofield, J. (2003). SiC thin-film Fabry–Perot interferometer for fiber-optic temperature sensor. IEEE Transactions on Electron Devices,50(10), 2159–2164.
Zhao, C. L., Demokan, M. S., Jin, W., & Xiao, L. (2007). A cheap and practical FBG temperature sensor utilizing a long-period grating in a photonic crystal fiber. Optics Communications,276(2), 242–245.
Li, X., Yu, H., Jiang, Y., & Zhang, D. (2011). Study of sensing properties of quartz fiber bragg grating sensor based on metalized encapsulation. In: Proceedings of 2011 international conference on electronic and mechanical engineering and information technology. https://doi.org/10.1109/EMEIT.2011.6023613.
Acknowledgements
This research was supported by the Naval Research Board, Defence Research and Development Organization (Grant No. NRB-405/OEP/17-18) and SRM Institute of Science and Technology under ‘Selective Excellence Initiative Program’—SRMU/R/AR(A)/2017/126/1866.
Author information
Authors and Affiliations
Corresponding author
Additional information
Publisher's Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Rights and permissions
About this article
Cite this article
Samiappan, D., Kesarikiran, A.V.S., Chakravartula, V. et al. Enhancing Sensitivity of Fiber Bragg Grating-Based Temperature Sensors through Teflon Coating. Wireless Pers Commun 110, 593–604 (2020). https://doi.org/10.1007/s11277-019-06744-w
Published:
Issue Date:
DOI: https://doi.org/10.1007/s11277-019-06744-w