Fluorinated Polyimide-Film Based Temperature and Humidity Sensor Utilizing Fiber Bragg Grating

We propose and demonstrate a temperature and humidity sensor based on a fluorinated polyimide film and fiber Bragg grating. Moisture-induced film expansion or contraction causes an extra strain, which is transferred to the fiber Bragg grating and leads to a humidity-dependent wavelength shift. The h...

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Bibliographic Details
Published in:Sensors (Basel, Switzerland) Switzerland), 2020-09, Vol.20 (19), p.5469
Main Authors: Xu, Xiuxiu, Luo, Mingming, Liu, Jianfei, Luan, Nannan
Format: Article
Language:English
Subjects:
Accuracy
Bragg gratings
Crosstalk
Electromagnetism
Explosives
fiber Bragg grating
Field tests
fluorinated polyimide film
Fluorination
Humidity
humidity hysteresis
Letter
Moisture
Moisture absorption
Molecular weight
Relative humidity
Sensors
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Summary:We propose and demonstrate a temperature and humidity sensor based on a fluorinated polyimide film and fiber Bragg grating. Moisture-induced film expansion or contraction causes an extra strain, which is transferred to the fiber Bragg grating and leads to a humidity-dependent wavelength shift. The hydrophobic fluoride doping in the polyimide film helps to restrain its humidity hysteresis and provides a short moisture breathing time less than 2 min. Additionally, another cascaded fiber Bragg grating is used to exclude its thermal crosstalk, with a temperature accuracy of ±0.5 °C. Experimental monitoring over 9000 min revealed a considerable humidity accuracy better than ±3% relative humidity, due to the sensitized separate film-grating structure. The passive and electromagnetic immune sensor proved itself in field tests and could have sensing applications in the electro-sensitive storage of fuel, explosives, and chemicals.
ISSN:1424-8220
1424-8220
DOI:10.3390/s20195469