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Performance study of surface plasmon resonance and lossy mode resonance based fiber optic sensors utilizing silver and indium oxide layers: An experimental investigation
摘要： This study presents here the experimental investigations on a surface plasmon resonance (SPR)/lossy mode resonance (LMR) based fiber optic sensors coated with silver and indium oxide layers. Different sensing probes have been fabricated by coating (i) a single layer of indium oxide, (ii) a single layer of silver and (iii) a double layer of indium oxide and silver (with different thicknesses) symmetrically onto to the bare core of silica fiber. The sensitivity of these fiber optic sensing probes towards surrounding region refractive index variations are determined using different concentrations of sucrose solutions. It was found that sensor probe fabricated with coating of 100 nm thickness of indium oxide was two times more sensitive than the conventionally used fiber optic sensing probe coated with only silver layer. The sensitivity of a double layer coated fiber optic sensor with various thicknesses of indium oxide and silver layers is in between the two extremes of the sensitivities. This study will find suitable applications in the field of chemical and biochemical sensing. The drawbacks of silver coatings and the advantages of LMR supporting indium oxide have also been discussed.
关键词： Surface plasmons,Sensitivity,Lossy mode resonances,Thin films,Fiber optic sensors,Detection accuracy,Indium oxide
更新于2025-09-23 15:21:21
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Photothermal Effects Induced by Surface Plasmon Resonance at Graphene/Gold Nanointerfaces: A Multiscale Modeling Study
摘要： Surface plasmon resonance (SPR) biosensors have enormous potential in biological recognitions and biomolecular interactions, especially for the real time measurement of disease diagnosis and drug screening. Extensive efforts have been invested to ameliorate the sensing performances, while the photothermal effects, which are induced by the plasmon resonance, have an obvious impact. However, due to the limitations of experimental approaches, the theoretical mechanisms and specific influences of the SPR sensors with photothermal effects are few researched. Here, a multiscale simulation method is developed to investigate the photothermal effects at graphene/gold (Au) nanointerfaces, and to calculate the quantitative contribution of the photothermal effects towards high reliability SPR sensors in order to elucidate their influence on the sensing performances by means of first-principle calculations and molecular dynamics simulations. Our results indicate that the sensitivity and detection accuracy of graphene/Au SPR sensors can be tailored from 0 K to 600 K, due to the tunable dielectric constants of Au and graphene films through temperature variation. By controlling the its material thickness, interfacial combination and lattice strain, an optimized graphene/Au SPR sensor with higher sensitivity, detection accuracy, and reliability to the temperature rising has been achieved. Such multiscale simulation method, which is capable of seeking both the role and the underlying mechanism of the interfacial phenomena, can serve as an excellent guideline for the performance optimization and commercialized application of SPR sensors in the analytical chemistry and biomedical fields.
关键词： graphene/gold nanointerface,photothermal effects,surface plasmon resonance,multiscale simulation method,sensitivity and detection accuracy
更新于2025-09-23 15:21:21
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Two-dimensional transition metal dichalcogenides mediated long range surface plasmon resonance biosensors
摘要： Two-dimensional transition metal dichalcogenides (TMDCs), as promising alternative plasmon supporting materials to graphene, exhibit potential applications in sensing. Here, we propose a TMDCs-mediated long range surface plasmon resonance (LRSPR) imaging biosensor, which shows tremendous improvements in both imaging sensitivity (> ×2) and detection accuracy (> ×10) as compared to conventional surface plasmon resonance (cSPR) biosensor. It is found that the imaging sensitivity of the LRSPR biosensor can be enhanced by the integration of TMDC layers, which is di?erent from the previously reported graphene-mediated cSPR imaging sensor whose imaging sensitivity decreases with the number of graphene layers. This imaging sensitivity enhancement e?ect for the TMDCs-mediated LRSPR sensor originates from the propagating nature of the LRSPR at both interfaces of sensing medium/gold and gold/cytop layer (with matching refractive index as sensing medium). By tuning the thickness of gold ?lm and cytop layer, it is possible to achieve optimized imaging sensitivity for LRSPR sensor with any known integrated number of TMDC layers and the analyte refractive index. The proposed TMDCs-mediated LRSPR imaging sensor could provide potential applications in chemical sensing and biosensing applications.
关键词： detection accuracy,biosensor,long range surface plasmon resonance,Two-dimensional transition metal dichalcogenides,imaging sensitivity
更新于2025-09-23 15:21:01
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A Real-Time Method to Detect the Deformation Behavior during Laser Solid Forming of Thin-Wall Structure
摘要： Laser solid forming (LSF) is a promising additive manufacturing technology. In the LSF process, deformation behaviors dictate the accuracy of the produced parts. In this study, by using a laser displacement detector based on laser triangulation principle, an accurate and effective real-time detection method was established to monitor the real-time deformation behavior of the key position during the LSF of a thin-wall structure. The results confirmed that increasing thin-wall length results in increasing final deformation of the edge. The displacement fluctuation range and value in the middle of thin wall are both smaller than that of the positions near the end, while the entire displacement changing direction in the middle is opposite to that of the end positions. When the deposition process is paused, the deformation of the thin wall during the cooling stage will deviate the position of the deposited thin wall, resulting in the dislocation between the subsequent deposited part and that before the pause, which affect the dimensional accuracy of the thin wall structure. This non-contact real-time detection method also confirmed the ability to monitor the initiation of cracking during the LSF process, and a potential to be used for the on-line feedback control of deformation of detected key position of deposited structure.
关键词： laser solid forming,real-time detection,accuracy,crack,additive manufacturing,deformation behaviors
更新于2025-09-23 15:19:57
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Comparative study of defect mode intensity and wavelength modulation in Bragg fiber waveguide sensors
摘要： Sensing parameters of Bragg ?ber waveguides having a defect layer in the cladding region are studied theoretically for bio-sensing and thickness monitoring applications. A comparison between Bragg ?ber waveguides consist of a liquid-core surrounded with alternate high refractive index (R.I.) contrast of claddings and low R.I. contrast of claddings is presented. In non-homogeneous multilayer cylindrical system, the transmittance of proposed waveguide-based sensors is formulated using transfer matrix method and Hankel formalism. Both considered structures show photonic bandgap with a narrow passband in the bandgap region. This narrow passband is treated as sensing signal because its position and intensity depends on the diameter and refractive index of core material. The high refractive index contrast cladding waveguide shows larger intensity shift than low refractive index contrast cladding waveguide. The presence of defect layer in both considered waveguides is able to increase the sensing parameters like detection accuracy and overall performance.
关键词： Quality parameter,Liquid core Bragg ?ber waveguide,Defect mode,Detection accuracy,Sensitivity
更新于2025-09-23 15:19:57
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[IEEE 2018 IEEE International Electron Devices Meeting (IEDM) - San Francisco, CA, USA (2018.12.1-2018.12.5)] 2018 IEEE International Electron Devices Meeting (IEDM) - A CMOS Proximity Capacitance Image Sensor with <tex>$16\mu \mathrm{m}$</tex> Pixel Pitch, 0.1aF Detection Accuracy and 60 Frames Per Second
摘要： A 16μm pitch 256×256 frames per second CMOS proximity capacitance image sensor fabricated by a 0.18μm CMOS process technology is presented. By the introduction of noise canceling operation, both fixed pattern noise (FPN) and kTC noise are significantly reduced, resulting in the 0.1aF (10-19F) detection accuracy. Proximity capacitance imaging results using the developed sensor are also demonstrated.
关键词： detection accuracy,CMOS,noise canceling,kTC noise,60 fps,proximity capacitance image sensor,0.1aF,FPN
更新于2025-09-19 17:15:36
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Design considerations of a surface plasmon resonance (SPR) based tapered fiber optic bio-sensing probe with graphene-MoS2 over layers
摘要： In this paper, we have reported the design considerations of a surface plasmon resonance (SPR) based tapered fiber optic sensor by coating a thin film of platinum on a tapered fiber core followed by graphene-molybdenum disulphide (MoS2) monolayers. The theoretical study is based on five-layer matrix model. To see the effect of graphene-MoS2 over layers, performance parameters in terms of sensitivity and detection accuracy are evaluated for four taper profiles viz. exponential-linear, linear, parabolic and quadratic along with the taper ratio. From results, we inferred that with increase in taper ratio sensitivity also increases while detection accuracy decreases monotonically. For the proposed sensor configuration, maximum sensitivity value is found to be 7.04μm/RIU at taper ratio 2.0 for exponential-linear taper profile while maximum detection accuracy obtained is 16.7623μm-1, at taper ratio 1.0. Thus, the results show that by introducing additional graphene-MoS2 monolayers, the sensitivity of the proposed sensing probe is enhanced by more than 44% at taper ratio 2 as compared to the conventionally used SPR based fiber optic sensors coated with platinum only. Also, the effect of increasing number of layers of graphene and MoS2 on the performance parameters is evaluated and compared. The advantageous features of the graphene and MoS2 layers have also been discussed for bio-sensing applications.
关键词： surface plasmon resonance,graphene,Fiber optic sensors,sensitivity and detection accuracy,molybdenum di-sulphide
更新于2025-09-09 09:28:46