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Lossy Mode Resonance Generation by Graphene Oxide Coatings onto Cladding-Removed Multimode Optical Fiber
摘要： In this work, we have studied the suitability of graphene oxide-based thin films to be not only excellent sensitive coatings but also lossy mode resonance (LMR)-generating materials. Thin films of graphene oxide (GO) and polyethylenimine (PEI) fabricated by means of layer-by-layer assembly were selected in this study. Two optical fiber devices with 8 and 20 bilayers of the LMR-generating coating were fabricated and characterized as refractometers. Both devices show no hysteresis and high sensitivity, improving previously reported values. This research opens very promising and exciting possibilities in the field of optical fiber sensors based on LMR, strategically including specific recognition groups to the device surface to exploit this high sensitivity for monitoring a range of target analytes. The carboxylate functional groups at the edges of the GO sheets should provide excellent attachment sites for the required coupling chemistry to realize such devices.
关键词： optical fiber sensor,thin films,Dip-assisted layer by layer,lossy mode resonance,refractometer,graphene oxide
更新于2025-11-14 15:19:41
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High-performance optical fiber humidity sensor based on lossy mode resonance using a nanostructured polyethylenimine and graphene oxide coating
摘要： In this study, a rapid optical fiber sensor for humidity with high sensitivity and wide detection range has been constructed, based on lossy mode resonance (LMR). A thin film made of alternating polyethylenimine (PEI) and graphene oxide (GO) layers was selected as sensitive coating. It was deposited on a SnO2-sputtered fiber core in a dip-assisted layer-by-layer assembly. The structure and surface chemistry of the raw materials were investigated by means of Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Key properties such as sensitivity, linearity, hysteresis, stability and response and recovery times were characterized. The sensor exhibited excellent sensitivity, especially at high relative humidity (RH) levels, and short reaction and retrieval periods. This research provides a viable and practical way to fabricate high performance humidity optical fiber sensors with GO-based nanostructured coatings.
关键词： relative humidity sensor,layer-by-layer,breathing monitoring,graphene oxide,lossy mode resonance,Optical fiber sensor
更新于2025-09-19 17:15:36
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Electrochemical performance of indium-tin-oxide-coated lossy-mode resonance optical fiber sensor
摘要： Analysis of liquids performed in multiple domain, e.g., optical and electrochemical (EC), has recently focus significant attention. Our previous works have shown that a simple device based on indium-tin-oxide (ITO) coated optical fiber core may be used for optical monitoring of EC processes. At satisfying optical properties and thickness of ITO a lossy-mode resonance (LMR) effect can be obtained and used for monitoring of optical properties of an analyte in proximity of the ITO surface. However, EC response of the ITO-LMR device to a redox probe has not been achieved for ITO-LMR sensor whereas it is generally observed for commercially available ITO electrodes. The changes in the response to a redox probe are typically used as a sensing parameter when EC label-free sensing is considered, so it is crucial for further development of combined LMR-EC sensing concept. In this work, we focus on enhancing the EC activity of the device by tuning ITO magnetron sputtering deposition parameters. Influence of the deposition pressure on the ITO properties has been the main consideration. Both optical and EC readouts in 0.1 M KCl containing such redox probes as 1 mM of K3[Fe(CN)6] or 1 mM 1,1′-Ferrocenedimethanol were discussed at different scan rate. The performed studies confirm that for optimized ITO properties the ITO-LMR sensor used as the EC electrode may also show excellent EC performance. The observed EC processes are quasi-reversible and diffusion-controlled. Moreover, for the devices, which offer improved EC response, an optical monitoring of the EC process is also possible. According to our best knowledge, fully functional combined optical and EC sensor, where optical effect is resonance-based and other than well-known surface plasmon resonance, is presented for the first time.
关键词： Electrochemical properties,Cyclic voltammetry,Optical properties,Lossy-mode resonance,Optical fiber sensor,Indium tin oxide,Magnetron sputtering
更新于2025-09-16 10:30:52
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Lossy Mode Resonance Generation on Sputtered Aluminum-Doped Zinc Oxide Thin Films Deposited on Multimode Optical Fiber Structures for Sensing Applications in the 1.55 μm Wavelength Range
摘要： In this work, we demonstrated lossy mode resonance (LMR) generation in optical fiber structures based on multimode fibers coated with aluminum-doped zinc oxide (AZO) films. AZO thin films were deposited by using radio frequency magnetron sputtering. In order to exhibit the usefulness of the LMR effect for sensing applications in optical fiber based systems, the deposition conditions of the AZO film coatings were set to obtain the second LMR order within the 1.55 μm wavelength range. An optical transmission configuration setup was used to investigate the LMR effect on fiber structures based on the use of no-core and cladding-removed multimode fibers coated with AZO films synthesized from metallic sputtering targets with different proportions of Zn:Al, 92:8% and 98:2%, at atomic concentrations. The optical and electrical/chemical features of the AZO films were characterized with UV–vis and XPS spectroscopy, respectively. The optical response of the proposed sensing configuration to refractive index (RI) variations was experimentally demonstrated. For the best approach, the sensitivity of wavelength displacement to RI variations on the liquid surrounding media was found to be 1214.7 nm/RIU.
关键词： multimode fiber,lossy mode resonance,optical fiber sensors,reactive RF magnetron sputtering,aluminum-doped zinc oxide
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Lossy Mode Resonance Fiber-Optic Biosensing Allowing Ultra-Low Detection Limit
摘要： Fiber-optic biosensors can offer great advantages over other optical technology platforms thanks to the typical features of optical fibers. Moreover, the opportunity of depositing nm-thick overlays on optical fibers with a high degree of accuracy, repeatability and reproducibility has enabled spreading the application domains of this technology. Recently, the concept of guided mode resonance has been exploited in thin film coated fiber-optic sensors, under the name of lossy mode resonance (LMR). LMR occurs when the real part of the thin film permittivity is positive and greater in magnitude than both its own imaginary part and the permittivity of the material surrounding the thin film. Therefore, metallic oxides and polymers can be used to generate LMRs, instead of the noble metals typically used in SPR devices. Instead of using multi-mode fibers, D-shaped single-mode fibers have been used to excite LMR, which enables tracking the spectral displacement of the 1st LMR, the most sensitive LMR, at wavelengths in the NIR, where the sensitivity is enhanced if compared to the visible region. By coating the D-shaped region of the fiber with a nanometric layer of tin oxide (SnO2) and integrating it into an ad-hoc microfluidic system, an ultra-low detection limit (LOD) biosensing device has been developed. The sensing principle is quite simple: when the target analyte interacts with the fiber-functionalized surface, this induces a change in the optical properties of the overlay (i.e. effective refractive index and thickness); in turn, this causes a change in the spectral position of the LMR that can be accurately and precisely measured through a conventional wavelength interrogation system. The deposition of the tin oxide layer (roughly 160-180 nm), which is performed with a DC sputter machine (ND-SCS200, Nadetech S.L.), has been characterized by FESEM images (UltraPlus Carl Zeiss Inc.). The round inset of the same figure details the functionalization of the sensitive region, which is carried out with the deposition of a nm-thick polymeric layer of poly(methyl-methacrylate) (Eudragit L100) that provides free functionalities necessary for the IgG antibody immobilization. The assay has been completed by spiking increasing concentrations of anti-IgG antigen (from 1 pg mL-1 up to 10 μg mL-1) in a real sample of CRP-free human serum. The real-time tracking of the LMR shift has enabled following all the biochemical steps during the assay implementation and then the calibration curve (n=4) of the proposed biosensor has been obtained, together with the sigmoidal fit with the Hill function, which is a well-accepted mathematical model used to quantify the degree of interaction between ligand binding sites. A LOD of 150 fg mL-1 has been attained. This result has confirmed a big leap in performance thanks to the capability to detect analyte concentrations down to few fM in real samples, enhancing the LOD by three orders of magnitude when compared with other fiber-based configurations and matching a LOD comparable with the most outstanding optical technology platforms.
关键词： Fiber-optic biosensors,lossy mode resonance,microfluidic system,ultra-low detection limit,tin oxide
更新于2025-09-11 14:15:04