Abstract
The influence of the bending radius on the sensitivity of the graphene quantum dots (GQDs)-coated probe is experimentally investigated for a U-shaped probe. The fiber is bent into a U shape using the optic fiber flame heating method, and the optic fiber is enclosed in a glass tube to increase the stability of the probe. The surface of the U-shaped optical fiber was coated with electrospun fibers formed via electrospinning. Polymer materials doped with GQDs are applied to U-shaped optical fiber as humidity sensors. Graphene quantum dot nanofibers on the U-shaped optical fiber sensor to form a network structure of graphene quantum dots U-shape fiber sensor (GQDUS). The polymer network structure absorbs water molecules, which in turn affects the bending radius of the optical fiber, and changes the optical fiber spectrum. Graphene quantum dots provide optical enhancement benefits, which in turn increase the sensitivity of fiber optic sensors. The spectra monitoring system consists of an optical spectrum analyzer (OSA) and an amplified spontaneous emission (ASE). This system can be used to detect humidity changes between 20% RH and 80% RH in the chamber. Our results indicate promising applications for quantum dots probe sensors from electrospun nanofibers increasing sensitive environmental monitoring. As such, it could be of substantial value in optical sensors detection.
Highlights
Optical fibers are part of everyday life, especially in communications, where they are used to convey information
The results showed that the electrical resistivity of the sensors gradually decreased, proving that NiO–SnO2 nanofibers can be used as the active nanostructures in humidity sensors
Combining and building on these previous studies, this research employed electrospinning techniques to coat a layer of composite polyvinyl alcohol (PVA)–graphene quantum dots (GQDs) film onto the surface of a U-shaped optical fiber probe sensor for humidity measurement applications
Summary
Optical fibers are part of everyday life, especially in communications, where they are used to convey information. The optical sensors were electrospun using a solution of poly(acrylic acid)−poly(pyrene methanol) (PAA−PM) and thermally cross-linkable polyurethane–latex These sensors exhibited higher sensitivities because of the high specific surface areas of the nanofibrous membrane structures. In 2019, Zhao et al [27] constructed a U-shaped probe-type humidity sensor and improved its sensitivity by coating it with a layer of PVA film. Combining and building on these previous studies, this research employed electrospinning techniques to coat a layer of composite PVA–GQDs film onto the surface of a U-shaped optical fiber probe sensor for humidity measurement applications. The high specific surface area, as well as the specificity of the electrospun film of the material, could improve the sensitivity of the sensor during the humidity measurements. According to the previous wavelength-related equations, the wavelength shifts are primarily affected by three parameters—the diameter of the optical fiber, the bend radius, and the effective refractive index
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