Compact relative humidity sensor based on an Agarose hydrogel coated silica microsphere resonator

Arun Kumar Mallik, Dejun Liu, Vishnu Kavungal, Xiaokang Lian, Gerald Farrell, Qiang Wu, Yuliya Semenova

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

Abstract

In this paper, we propose a novel approach to measurements of low relative humidity (RH) levels based on the whispering gallery modes (WGMs) phenomenon in a silica microsphere resonator coated with Agarose. The spectral dips of the WGM resonances excited in the proposed sensor depend strongly on the changes in the refractive index (RI) of the coating material as well as the surrounding RI. A study of the humidity-induced RI changes in a thin Agarose layer, applied to the surface of a 162 μm-diameter silica microsphere was carried out by correlating the experimental results and numerical simulations performed using the perturbation theory. We experimentally demonstrate a linear sensing characteristic in a low-humidity range from 10% to 45% RH. The estimated quality factor of the micro-resonator is 2.82×106 and detection limit for the sensor is 0.057 %RH, corresponding to the RI resolution of 8.4×10-7 RIU.

Original languageEnglish
Title of host publication25th International Conference on Optical Fiber Sensors
EditorsLibo Yuan, Youngjoo Chung, Wei Jin, Byoungho Lee, John Canning, Kentaro Nakamura
PublisherSPIE
ISBN (Electronic)9781510610910
DOIs
Publication statusPublished - 2017
Event25th International Conference on Optical Fiber Sensors, OFS 2017 - Jeju, Korea, Republic of
Duration: 24 Apr 201728 Apr 2017

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
Volume10323
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X

Conference

Conference25th International Conference on Optical Fiber Sensors, OFS 2017
Country/TerritoryKorea, Republic of
CityJeju
Period24/04/1728/04/17

Keywords

  • Fiber optic sensors
  • Relative humidity sensing
  • Whispering gallery mode micro-resonator

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