Hygroscopic Materials and Characterization Techniques for Fiber Sensing Applications: A Review

Abstract

Various characterization techniques are used in the study of materials in order to understand their properties. Data and observation recording characterization of a material is done by researchers for various properties within various environments. One of the many properties that make a material attractive for use in certain devices is hygroscopicity. Various techniques for characterizing hygroscopicity have been developed and utilized. However, since these techniques are not usually the highlights of studies, there has been limited acknowledgement of the usefulness of hygroscopicity testing. This review introduces several established characterization techniques allowing researchers to fully characterize materials in terms of their hygroscopicity. The full potential of hygroscopic materials can be seen in their use in various fiber sensors. The deformation of materials upon exposure to water molecules can be utilized to perturb sensing elements in fiber sensors, allowing the user to take full advantage of the hygroscopicity of the material.

Citrus Waste Upcycling toward Pectin Moisturizer Films Plasticized with Glycerol and Polyethylene Glycol

“…Therefore, the viscoelasticity results are also valid, attributed to the hydrophilic nature of GLY and PEG. Since GLY and PEG are known for their hygroscopic properties, , meaning they have a strong tendency to absorb and retain moisture, their plasticized films facilitated the absorption of water molecules, leading to a faster dissolution process …”

“…Since GLY and PEG are known for their hygroscopic properties, 39,40 meaning they have a strong tendency to absorb and retain moisture, their plasticized films facilitated the absorption of water molecules, leading to a faster dissolution process. 41 3.3. Properties of Pectin Plasticized Films on Moisturizer.…”

Optimal etching process and cladding dimension for improved coating of porous hemispherical ZnO nanostructure on FBG humidity sensor

“…The sensitive point of the fiber, which causes the variation of refractive indices, is the grating segment imprinted in the fiber core. FBG sensing has been used in environmental and chemical sensing applications [3].…”

Humidity sensor based on optical fiber Bragg grating with high sensitivity and fast response

“…Therefore, the choice of humidity-sensitive material becomes critical. Currently, humidity-sensitive materials are primarily polymers, including polyimide (PI), 5 polyvinyl acetate, 6 polymethyl methacrylate (PMMA), and agar. 7 Swanson et al 8 studied the response of PMMA and its copolymer-coated FBGs, revealing non-linear sensor output increases above 70% relative humidity (RH).…”

“…Therefore, the choice of humidity-sensitive material becomes critical. Currently, humidity-sensitive materials are primarily polymers, including polyimide (PI), 5 polyvinyl acetate, 6 polymethyl methacrylate (PMMA), and agar 7 . Swanson et al 8 .…”