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Micromachines 2016, 7(3), 35;

Sandwiched Long-Period Fiber Grating Fabricated by MEMS Process for CO2 Gas Detection

Department of Mechanical Engineering, National Kaohsiung University of Applied Sciences, Kaohsiung 807, Taiwan
Author to whom correspondence should be addressed.
Academic Editors: Her-Terng Yau, Chien-Hung Liu and Joost Lötters
Received: 27 November 2015 / Revised: 16 February 2016 / Accepted: 18 February 2016 / Published: 25 February 2016
(This article belongs to the Special Issue Recent Advances in Smart System)
Full-Text   |   PDF [3672 KB, uploaded 25 February 2016]   |  


This paper presents an optical fiber gas sensor based on sandwiched long-period fiber grating (SLPFG) that is fabricated via the microelectromechanical systems (MEMS) process and coated with amino silica adsorbent for carbon dioxide (CO2) gas sensing. The amine-modified nanoporous silica foams were coated onto the SLPFG for CO2 adsorption. To characterize the CO2 adsorption of the SLPFG sensor, a gas sensing test was conducted with a mixed gas consisting of 15% CO2 and 85% nitrogen at a flow rate of 0.2 L/min. The results showed that the spectra of the SLPFG were varied with the gas flow within 21 min. After that, the transmission spectra of the SLPFG held steady and exhibited no further change. This phenomenon was caused by the adsorption saturation of the amine-modified nanoporous silica foams which were coated onto the SLPFG. During the absorption process, the transmission was increasing by about 11.27 dB (from −23.11 to −11.84 dB), and the increasing rate of transmission was 0.4598 dB/min. Repeatable adsorption and desorption experiment results showed that the SLPFG CO2 gas sensor exhibited good repeatability and a short response time. The recovery rate for each cycle was about 85%, and the required recovery time was short. Therefore, elaborated SLPFG gas sensor could potentially be used as a gas sensor for monitoring CO2 adsorption in the context of various industrial, agricultural, and household applications. View Full-Text
Keywords: optical fiber sensor; nanoporous; carbon dioxide optical fiber sensor; nanoporous; carbon dioxide

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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

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Wu, C.-W.; Chiang, C.-C. Sandwiched Long-Period Fiber Grating Fabricated by MEMS Process for CO2 Gas Detection. Micromachines 2016, 7, 35.

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