{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,12]],"date-time":"2025-10-12T04:04:14Z","timestamp":1760241854700,"version":"build-2065373602"},"reference-count":22,"publisher":"MDPI AG","issue":"10","license":[{"start":{"date-parts":[[2018,9,22]],"date-time":"2018-09-22T00:00:00Z","timestamp":1537574400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>In this study, we applied a double-sided inductively coupled plasma (ICP) process to nanostructure long-period fiber grating (LPFG) in order to fabricate a double-notched LPFG (DNLPFG) sensor with a double-sided surface corrugated periodic grating. Using the sol-gel method, we also added thymol blue and ZnO to form a gas sensing layer, thus producing a DNLPFG CO2 gas sensor. The resulting sensor is the first double-sided etching sensor used to measure CO2. The experimental results showed that as the CO2 concentration increased, the transmission loss increased, and that the smaller the fiber diameter, the greater the sensitivity and the greater the change in transmission loss. When the diameter of the fiber was 32 \u03bcm (and the period was 570 \u03bcm) and the perfusion rate of CO2 gas was 15%, the maximum loss variation of up to 3.881 dB was achieved, while the sensitivity was 0.2146 dB\/% and the linearity was 0.992. These results demonstrate that the DNLPG CO2 gas sensor is highly sensitive.<\/jats:p>","DOI":"10.3390\/s18103206","type":"journal-article","created":{"date-parts":[[2018,9,24]],"date-time":"2018-09-24T10:38:49Z","timestamp":1537785529000},"page":"3206","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["Double Notched Long-Period Fiber Grating Characterization for CO2 Gas Sensing Applications \u2020"],"prefix":"10.3390","volume":"18","author":[{"given":"Hsiang-Chang","family":"Hsu","sequence":"first","affiliation":[{"name":"Department of Mechanical Engineering, National Kaohsiung University of Sciences and Technology, NO.415 Jian-gong Road, Kaohsiung, Kaohsiung City 80778, Taiwan"}]},{"given":"Tso-Sheng","family":"Hsieh","sequence":"additional","affiliation":[{"name":"Department of Mechanical Engineering, National Kaohsiung University of Sciences and Technology, NO.415 Jian-gong Road, Kaohsiung, Kaohsiung City 80778, Taiwan"}]},{"given":"Tzu-Hsuan","family":"Huang","sequence":"additional","affiliation":[{"name":"Department of Mechanical Engineering, National Kaohsiung University of Sciences and Technology, NO.415 Jian-gong Road, Kaohsiung, Kaohsiung City 80778, Taiwan"}]},{"given":"Liren","family":"Tsai","sequence":"additional","affiliation":[{"name":"Department of Mechanical Engineering, National Kaohsiung University of Sciences and Technology, NO.415 Jian-gong Road, Kaohsiung, Kaohsiung City 80778, Taiwan"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2809-913X","authenticated-orcid":false,"given":"Chia-Chin","family":"Chiang","sequence":"additional","affiliation":[{"name":"Department of Mechanical Engineering, National Kaohsiung University of Sciences and Technology, NO.415 Jian-gong Road, Kaohsiung, Kaohsiung City 80778, Taiwan"}]}],"member":"1968","published-online":{"date-parts":[[2018,9,22]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"184","DOI":"10.1016\/j.sna.2016.04.033","article-title":"Application of FBG sensors for geotechnical health monitoring, a review of sensor design, implementation methods and packaging techniques","volume":"244","author":"Hong","year":"2016","journal-title":"Sens. Actuators A Phys."},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Kheiri, M., Zibaii, M., Sadeghi, J., and Latifi, H. (2011, January 13\u201316). Refractive index measurement by fat long period grating sensor on a single mode optical fiber. Proceedings of the Asia Communications and Photonics Conference and Exhibition (ACP), Shanghai, China.","DOI":"10.1364\/ACP.2011.83110B"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"4345","DOI":"10.1016\/j.ijleo.2013.02.010","article-title":"The effect of annealing and temperature on transmission spectra of long period gratings written in hydrogen loaded standard single mode fiber","volume":"124","author":"Libish","year":"2013","journal-title":"Optik"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"145","DOI":"10.1109\/LPT.2014.2363478","article-title":"CO2-Laser-induced long period fiber gratings in few mode fibers","volume":"27","author":"Wang","year":"2015","journal-title":"IEEE Photonics Technol. Lett."},{"key":"ref_5","doi-asserted-by":"crossref","unstructured":"Yin, G., Wang, Y., Liao, C., Zhou, J., Zhong, X., Liu, S., Wang, Q., Li, Z., Sun, B., and He, J. (2014, January 2\u20139). Improved arc discharge technique for inscribing comp act long period fiber gratings. Proceedings of the 23rd International Conference on Optical Fiber Sensors, Santander, Spain.","DOI":"10.1117\/12.2059261"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"55","DOI":"10.1016\/j.yofte.2012.11.002","article-title":"Temperature-sensitive mechanical LPFG using contractive force of heat-shrinkable tube","volume":"19","author":"Tsutsumi","year":"2013","journal-title":"Opt. Fiber Technol."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"39","DOI":"10.1016\/j.optcom.2014.05.046","article-title":"Improved detecting sensitivity of long period fiber gratings by polyelectrolyte multilayers: The effect of film structures","volume":"331","author":"Li","year":"2014","journal-title":"Opt. Commun."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"3677","DOI":"10.1364\/OL.34.003677","article-title":"Sandwiched long-period fiber grating filter based on periodic SU8-thick photoresist technique","volume":"34","author":"Chiang","year":"2009","journal-title":"Opt. Lett."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"193","DOI":"10.1364\/OL.37.000193","article-title":"Perfectly notched long-period fiber grating filter based on ICP dry etching technique","volume":"37","author":"Chiang","year":"2012","journal-title":"Opt. Lett."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"4217","DOI":"10.1175\/JCLI-D-14-00036.1","article-title":"The origin and limits of the near proportionality between climate warming and cumulative CO2 emissions","volume":"28","author":"MacDougall","year":"2015","journal-title":"J. Clim."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"229","DOI":"10.2165\/00139709-200524040-00003","article-title":"Carbon dioxide poisoning","volume":"24","author":"Langford","year":"2005","journal-title":"Toxicol. Rev."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"5469","DOI":"10.3390\/s100605469","article-title":"Metal oxide semi-conductor gas sensors in environmental monitoring","volume":"10","author":"Fine","year":"2010","journal-title":"Sensors"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"366","DOI":"10.3390\/s20900366","article-title":"Study on the characteristics of Ag doped CuO-BaTiO3 CO2 sensors","volume":"2","author":"Jiao","year":"2002","journal-title":"Sensors"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"120","DOI":"10.1016\/j.snb.2007.07.082","article-title":"Fiber-optic carbon dioxide sensor based on fluorinated xerogels doped with HPTS","volume":"129","author":"Chu","year":"2008","journal-title":"Sens. Actuators B Chem."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"4686","DOI":"10.3390\/s100504686","article-title":"Diode laser detection of greenhouse gases in the near-infrared region by wavelength modulation spectroscopy: Pressure dependence of the detection sensitivity","volume":"10","author":"Asakawa","year":"2010","journal-title":"Sensors"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"7079","DOI":"10.3390\/s130607079","article-title":"A novel solid state non-dispersive infrared CO2 gas sensor compatible with wireless and portable deployment","volume":"13","author":"Gibson","year":"2013","journal-title":"Sensors"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"276","DOI":"10.1016\/S0925-4005(03)00372-1","article-title":"Sensitivity of fiber-optic carbon dioxide sensors utilizing indicator dye","volume":"94","author":"Segawa","year":"2003","journal-title":"Sens. Actuators B Chem."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"R49","DOI":"10.1088\/0957-0233\/14\/5\/201","article-title":"Optical fibre long-period grating sensors: Characteristics and application","volume":"14","author":"James","year":"2003","journal-title":"Meas. Sci. Technol."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"4535","DOI":"10.3390\/ma8074535","article-title":"Notched Long-Period Fiber Grating with an Amine-Modified Surface Nanostructure for Carbon Dioxide Gas Sensing","volume":"8","author":"Wu","year":"2015","journal-title":"Materials"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"205","DOI":"10.1016\/j.snb.2009.09.019","article-title":"Highly sensitive and linear optical fiber carbon dioxide sensor based on sol-gel matrix doped with silica particles and HPTS","volume":"143","author":"Chu","year":"2009","journal-title":"Sens. Actuators B Chem."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"1159","DOI":"10.1109\/50.939797","article-title":"Corrugated long-period fiber gratings as strain, torsion, and bending sensors","volume":"19","author":"Lin","year":"2001","journal-title":"J. Lightw. Technol."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"4398","DOI":"10.1364\/AO.53.004398","article-title":"Characterization of notched long-period fiber gratings: effects of periods, cladding thicknesses, and etching depths","volume":"53","author":"Chiang","year":"2014","journal-title":"Appl. Opt."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/18\/10\/3206\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T15:22:01Z","timestamp":1760196121000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/18\/10\/3206"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2018,9,22]]},"references-count":22,"journal-issue":{"issue":"10","published-online":{"date-parts":[[2018,10]]}},"alternative-id":["s18103206"],"URL":"https:\/\/doi.org\/10.3390\/s18103206","relation":{},"ISSN":["1424-8220"],"issn-type":[{"type":"electronic","value":"1424-8220"}],"subject":[],"published":{"date-parts":[[2018,9,22]]}}}