• Journal of Sensor Science and Technology
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• v.17 no.2
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• pp.95-99
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• 2008

Various etching methods of optical fiber and formation of metal nano particles on the optical fiber have been proposed for fabrication of fiber optic localized surface plasmon resonance (FO LSPR) biosensors. Different types of etched optical fiber are possible by removing the cladding of optical fiber using HF (hydrofluoric acid) solution and BHF (buffered hydrofluoric acid) solution, which results in improved surface roughness when BHF solution is used. Localized surface plasmon can be formed and measured by formation of silver and gold nano particles on the etched optical fiber. The characteristics of the etched optical fiber and metal nano particles on the etched surface of the optical fiber play a key role in dictating the sensitivity of the LSPR sensors, so that the proposed results can be expected to be applied for related research on fiber optic based biosensors.

• Journal of Sensor Science and Technology
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• v.15 no.4
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• pp.263-268
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• 2006

We have demonstrated a highly sensitive temperature sensor using an etched single mode fiber with a thermally expanded core region. Large core size of thermally expanded core facilitates access to evanescent wave by the wet etching. The etched region was surrounded by a low dispersive external medium with high thermo-optic coefficient. Due to the large difference between the dispersion property of the fiber and that of the external medium, the device reveals a cut-off properties at spectral region. The cut-off wavelength was shifted by the variations of the environmental temperatures because of thermo-optic effect of the external medium. The sensitivity of the fabricated device was found to be $45nm/^{\circ}C$.

• Korean Journal of Optics and Photonics
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• v.22 no.1
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• pp.1-4
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• 2011

A new fabrication technique of long-period fiber gratings with periodically surface-etched structures is proposed. Transmission characteristics of the periodically surface-etched long-period fiber gratings are improved by changing strain because of variation of coupling strength between the core and the cladding modes. The sensitivities of the periodically surface-etched long-period fiber gratings to strain, torsion, and ambient refractive index were measured. The strain and the torsion sensitivities were measured to be $-0.033\;dB/\mu\varepsilon$ and -1.30 nm m/rad, respectively. The ambient index sensitivity was measured to be -31.33 nm/RIU from a range from 1.33 to 1.42.

• Journal of Electrochemical Science and Technology
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• v.14 no.2
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• pp.184-193
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• 2023

This study investigates the effects of a carbon fiber layer formed on the surface of an etched aluminum current collector on the electrochemical properties of the activated carbon electrodes for an electric double layer capacitor. A particle size analyzer, field-emission SEM, and nitrogen adsorption/desorption isotherm analyzer are employed to analyze the structure of the carbon fiber layer. The electric and electrochemical properties of the activated carbon electrodes using a carbon fiber layer are evaluated using an electrode resistance meter and a charge-discharge tester, respectively. To uniformly coat the surface with carbon fiber, we applied a planetary mill process, adjusted the particle size, and prepared the carbon paste by dispersing in a binder. Subsequently, the carbon paste was coated on the surface of the etched aluminum current collector to form the carbon under layer, after which an activated carbon slurry was coated to form the electrodes. Based on the results, the interface resistance of the EDLC cell made of the current collector with the carbon fiber layer was reduced compared to the cell using the pristine current collector. The interfacial resistance decreased from 0.0143 Ω·cm² to a maximum of 0.0077 Ω·cm². And degradation reactions of the activated carbon electrodes are suppressed in the 3.3 V floating test. We infer that it is because the improved electric network of the carbon fiber layer coated on the current collector surface enhanced the electron collection and interfacial diffusion while protecting the surface of the cathode etched aluminum; thereby suppressing the formation of Al-F compounds.

• Journal of Sensor Science and Technology
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• v.22 no.2
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• pp.95-99
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• 2013

We proposed and demonstrated a fiber optic sensor for detecting the thermo-optic coefficient of a liquid, based on a cascade of two different FBGs. One of the two FBGs was etched, and its cladding was removed, for evanescent wave coupling with an external liquid. The Bragg wavelength of the non-etched FBG was used as a reference for the temperature of the surrounding liquid. The refractive index (RI) and thermo-optic (T-O) coefficient of a liquid can be detected from the difference between the Bragg wavelengths of the two FBGs, and the variation of the difference in accordance with temperature.

• Current Optics and Photonics
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• v.2 no.3
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• pp.221-225
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• 2018

We suggested the use of miniature hollow glass tubes having high ultraviolet (UV) transmission characteristics for the protection of optical-fiber-type UV sensors. We have recently proposed a highly sensitive optical sensor in the UV spectral range, using a fiber Bragg grating (FBG) coated with an azobenzene polymer as the photoresponsive material. In this study, we used UV-transparent miniature glass tubes to protect the etched FBG with the azobenzene polymer coating. This technique will be very useful for protecting various fiber-based UV sensors.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.34D no.11
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• pp.48-53
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• 1997

Volume hologram was recorded using reference beam form optical fiber taper. A singel mode fiber was chemically etced to make a taper structure, and we showed experimentally that the referencing by the irregular beam pattern from this taper structure could increase the storage density of photorefractive volume hologram. The spatial selectivity of the volume hologram with this method was increased by two times compared to the normal single mode fiber referencing case. A theoretical analysis with randomly phased plane model also confirmed the results.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.5
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• pp.960-968
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• 2002

In this research, the effects of fiber stacking sequence on damage behaviors of FML(Fiber Metal Laminates) subject to indentation loading. SOP (Singly Oriented Ply) FML and angle ply FML were fabricated to study fiber orientation effects and angle ply effects. FML were fabricated by using 1050 aluminum laminate and carbon/epoxy prepreg. To increase adhesive bonding strength, Al laminate was etched using FPL methods. The static indentation test were conducted by using UTM under the 2side clamped conditions. During the tests, load and displacement curve and crack initiation and propagation behaviors were investigated. As fiber orientation angle increases, the crack initiation load of SOP FML increases because the stiffness induced by fiber orientation is increased. The penetration load of SOP FML is influenced by the deformation tendency and boundary conditions. However, the macro-crack of angle ply FML was initiated by fiber breakage of lower ply because angle plies in Angle ply FML prevents the crack growth and consolidation. The Angle ply FML has a critical cross-angle which prevent crack growth and consolidation. Damage behavior of Angle ply FML is changed around the critical cross-angle.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.10 s.181
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• pp.2461-2468
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• 2000

In this paper, single fiber pull-out test is used to measure the interfacial bonding shear strength of $Ti_{50}-Ni_{50}$ shape memory alloy composite with temperature. Fiber and matrix of $Ti_{50}-Ni_{50}$ shape memory alloy composite are respectively $Ti_{50}-Ni_{50}$ shape memory alloy and epoxy resin. To strengthen the interfacial bonding shear stress, various surface treatments are used. They are the hand-sanded surface treatment, the acid etched surface treatment and the silane coupled surface treatment etc.. The interfacial bonding shear strength of surface treated shape memory alloy fiber is greater than that of surface untreated shape memory alloy fiber by from 10% to 16%. It is assured that the hand-sanded surface treatment and the acid etched surface treatment are the best way to strengthen the interfacial bonding shear strength of $Ti_{50}-Ni_{50}$ shape memory composite. The best treatment condition of surface is 10% HNO$_3$ solution in the etching method to strengthen the interfacial bonding shear strength of $Ti_{50}-Ni_{50}$ shape memory alloy composite.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.05a
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• pp.143-146
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• 2002

Unsized AS-4 carbon fibers were etched by RF plasma and then coated via plasma polymerization in order to enhance adhesion to vinyl ester resin. The gases utilized for the plasma etching were Ar, $N_2 and O_2$, while the monomers used for the plasma polymerization coating were acetylene, butadiene and acrylonitrile. The conditions for the plasma etching and the plasma polymerization were optimized by measuring interfacial adhesion with vinyl ester resin via micro-droplet tests. Among the treatment conditions, the combination of Ar plasma etching and acetylene plasma polymerization provided greatly improved interfacial shear strength (IFSS) of 69MPa compared to 43MPa with as-received carbon fiber. Based on the SEM analysis of failure surface and load-displacement curve, it was assume that the failure might be occurred at the carbon fiber and plasma polymer coating. The plasma etched and plasma polymer coated carbon fibers were subjected to analysis with SEM, XPS, FT-IR or Alpha-Step, and dynamic contact angles and tensile strengths were also evaluated. Plasma polymer coatings did not change tensile strength and surface roughness of fibers, but decreased water contact angle except butadiene plasma polymer coating, possibly owing to the functional groups introduced, as evidenced by FT-IR and XPS.