Theses and Dissertations

Lina Xu

Issuing Body

Mississippi State University

Advisor

Ma, Wenchao

Committee Member

Monts, David L

Committee Member

Tao, Shiquan

Date of Degree

8-7-2004

Document Type

Graduate Thesis - Open Access

Major

Physics

Degree Name

Master of Science

College

College of Arts and Sciences

Department

Department of Physics and Astronomy

Abstract

An optical fiber humidity sensor has been devised using a porous sol-gel silica (PSGS) coating as a transducer. Evanescent wave scattering (EWS) in the PSGS coating. PSGS particles are highly hydrophilic and have a strong tendency to absorb water molecules from the surrounding environment. The absorbed water molecules form a thin layer on the inner surface of the pores inside the porous silica and enhance EWS, from which an indicatory signal can be obtained. The humidity sensor presented in this thesis has a fast response, is reversible, low cost, and has a broad dynamic relative humidity range from 3.6?0-6% to 100% or humidity range from 1.2ppm to 30000ppm. Because of its multiple advantages, including immunity to electromagnetic interference, resistance to corrosive environments, and high sensitivity, this humidity sensor has various applications. In soil moisture sensing, this humidity sensor can avoid the interference caused by compounds in soil water. For electrical transformer moisture sensing, this humidity sensor can avoid the effect of electromagnetic fields.

URI

https://hdl.handle.net/11668/20257

Comments

relative humidity||evanescent wave||scattering||sol gel silica

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