Compact Fiber Fabry–Perot Sensors filled with PNIPAM hydrogel for highly Sensitive Relative Humidity Measurement

Ru-lei Xia, Juan Liu, Jiulin Shi, Xing-Dao He, Jinhui Yuan, Andrew R. Pike, Liang Chu, Qiang Wu, Bin Liu

Research output: Contribution to journalArticlepeer-review

Abstract

A fiber-optic Fabry–Perot (FP) based relative humidity (RH) sensor was proposed and experimentally investigated by using Poly(N-isopropylacrylamide) (PNIPAM) hydrogel to connect two ends of single-mode optical fiber to formulate a PNIPAM FP cavity. The water vapor will be absorbed by the PNIPAM hydrogel, which will alter both the refractive index (RI) and dimension of the PNIPAM FP cavity, resulting in the change of output resonance intensity in the reflective spectrum. The measure RH sensitivity is 1.634 nm/%RH within RH range from 45-75% with good linearity of 0.9897 and excellent repeatability. The influence of PNIPAM hydrogel concentration on the RH sensitivity has been investigated - the higher the concentration of PNIPAM hydrogel, the higher the RH sensitivity of the sensor. The developed sensor can effectively monitor human respiratory with response and recovery time of 0.91 s and 1.91 s, respectively.
Original languageEnglish
Article number111781
Number of pages8
JournalMeasurement
Volume201
Early online date20 Aug 2022
DOIs
Publication statusPublished - 30 Sep 2022

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