Resonance Angle Research Articles

Optical Based Surface Plasmon Resonance Sensor for the Detection of the Various Kind of Cancerous Cell.

This research explores a novel biosensor design that exhibits much higher sensitivity compared to conventional biosensors. The biosensor's uniqueness originated from its innovative structure, which incorporates N-FK51A/Ag/AlON/BlueP materials, as well as its cutting-edge fabrication method. The refractive index component was considered when designing the SPR biosensor, which was developed from the angular analysis of the attenuated total reflection (ATR) approach for cancer detection. For instance, the resonance angle shifts by 15.57 deg when the refractive index changes from 1.360 to 1.401, demonstrating the sensor's responsiveness to variation in the refractive index. The sensitivities for skin (basal), cervical (HeLa), blood (Jurkat), adrenal gland (PC12), and breast (MDA-MB-231 and MCF-7) cancer cells were 197.65, 243.66, 255.36, 302.71, 372.57, and 416.85 deg/RIU, respectively. Also, the detection accuracy (DA), the figure of merit (FoM), and the quality factor were 0.37/deg, 155.94 (deg/RIU), and 26.71 RIU-1. We also examine the effects of substituting the noble, dielectric, 2D material layer with conventional biosensor materials for six cancers. Each time, the Ag/AION/BlueP layered structure performed best in distinguishing cancer cells from healthy cells. We also study the prism effects. The proposed biosensor, with a RI of 1.29-1.40, has a linear regression coefficient of R2 of 0.96094.

Mean-motion resonances with interfering density waves

ABSTRACT In this work, we study the dynamics of two less massive objects moving around a central massive object, which are all embedded within a thin accretion disc. In addition to the gravitational interaction between these objects, the disc–object interaction is also crucial for describing the long-term dynamics of the multibody system, especially in the regime of mean-motion resonances. We point out that near the resonance the density waves generated by the two moving objects generally coherently interfere with each other, giving rise to extra angular momentum fluxes. The resulting backreaction on the objects is derived within the thin-disc scenario, which explicitly depends on the resonant angle and sensitively depends on the smoothing scheme used in the two-dimensional theory. We have performed hydrodynamical simulations with planets embedded within a thin accretion disc and have found qualitatively agreement on the signatures of interfering density waves by measuring the torques on the embedded objects, for the cases of $2:1$ and $3:2$ resonance. By including in interference torque and the migration torques in the evolution of a pair of planets, we show that the chance of resonance trapping depends on the sign of the interference torque. For negative interference torques the pairs are more likely located at off-resonance regimes. The negative interference torques may also explain the $1~{{\ \rm per\ cent}}-2~{{\ \rm per\ cent}}$ offset (for the period ratios) from the exact resonance values as observed in Kepler multiplanet systems.

Study of effect of nanomaterial above the add layer on performance parameters of plasmonic structure

In this paper, we explored the effect of adding a nanomaterial layer above the add layer on performance parameter of the considered plasmonic structures (conventional, four and five layer SPR sensors). These structures are stimulated by the COMSOL Multiphysics. We have considered LiNbO3 as an add layer over a thin film of gold. Further, Graphene, Black Phosphorene, Mxene, MoS2 MoSe2, WS2 and WSe2 as nanomaterial are considered over add-layer. First, we optimised the thickness gold and LiNbO3. After that, we calculated reflectance and magnetic field dependent performance parameters, i.e., shift in resonance angle (∆θr), full beam width (FBW), sensitivity (S), detection accuracy (DA), quality factor (Q. F.), figure of merit (FoM), field intensity at different interfaces (metal-sensing medium (M-S), metal-dielectric (M-D), dielectric-sensing medium (D-S), dielectric-nanomaterial (D-N), nanomaterial-sensing medium (N-S), and penetration depth (PD) for the considered plasmonic structures. The minimum ∆θr is obtained for conventional structure i.e. 1.492° and maximum ∆θr is obtained for WS2 as nanomaterial used in five layer SPR sensor i.e., 2.052°. Moreover, FBW is also maximum for five layer SPR sensor with WS2 as nanomaterial i.e., 6.8430°. Moreover, PD has maximum value for conventional SPR sensor i.e., 190.894 nm, 175.94 nm for four layer SPR sensor and less than 175.94 nm for five layer SPR sensor. This comparative study will help to choose add-layer with nanomaterial over add layer and metal thin film layer in a SPR sensor for the detection of analyte or molecules present in the sensing medium.

Controllable Goos-Hänchen Shift in Photonic Crystal Heterostructure Containing Anisotropic Graphene

In this study, we investigate the electrically and magnetically tunable Goos–Hänchen (GH) shift of a reflected light beam at terahertz frequencies. Our study focuses on a photonic crystal heterostructure incorporating a monolayer anisotropic graphene. We observe a tunable and enhanced GH shift facilitated by a drastic change in the reflected phase at the resonance angle owing to the excitation of the topological edge state. Considering the quantum response of graphene, we demonstrate the ability to switch positive and negative GH shifts through the manipulation of graphene’s conductivity properties. Moreover, we show that the GH shift can be actively tuned by the external electric field and magnetic field, as well as by controlling the structural parameters of the system. We believe that this tunable and enhanced GH shift scheme offers excellent potential for preparing terahertz shift devices.

Manipulating photonic spin Hall split based on nonlinear effect and surface plasmon resonance

In this work, we present a surface plasmon resonance (SPR) structure containing AuAl2 and a nonlinear Kerr medium. Based on the modulation of the refractive index of the Kerr medium by pumped light, we analyze the effects of the SPR structure and pumped light on the photonic spin Hall effect (PSHE). The numerical results indicate that the thickness of the AuAl2 exerts a profound impact on the SPR, while the intensity of the pump light (Ip) exerts a significant influence on the resonance angle. The transverse shift (TS) is very sensitive to the refractive index (RI) of the sensing layer after increasing through the SPR. Furthermore, it is observed that the sign of the TS of the PSHE can be modulated according to Ip within a specific angle of incidence. In light of these findings, we put forth a novel optical signal modulation and RI sensing scheme based on PSHE. Our study provides a new mechanism for practical applications of PSHE in optical communication and precision measurement.

The Solar System could have formed in a low-viscosity disc: A dynamical study from giant planet migration to the Nice model

Context. In the context of low-viscosity protoplanetary discs (PPDs), the formation scenarios of the Solar System should be revisited. In particular, the Jupiter-Saturn pair has been shown to lock in the 2:1 mean motion resonance while migrating generally inwards, making the Grand Tack scenario impossible. Aims. We explore what resonant chains of multiple giant planets can form in a low-viscosity disc, and whether these configurations can evolve into forming the Solar System in the post gas disc phase. Methods. We used hydrodynamical simulations with the code FARGOCA to study the migration of the giant planets in a disc with viscosity parameter of α = 10−4. After a transition phase to a gas-less configuration, we studied the stability of the obtained resonant chains through their interactions with a disc of leftover planetesimals by performing N-body simulations using rebound. Results. The gaps opened by giant planets are wider and deeper for lower viscosity, reducing the damping effect of the disc. Thus, when planets enter a resonance, the resonant angle remains closer to circulation, making the chain weaker. Exploring numerous configurations, we found five stable resonant chains of four or five planets. In a thin (cold) PPD, the four giant planets revert their migration and migrate outwards. After disc dispersal, under the influence of a belt of planetesimals, some resonant chains undergo an instability phase while others migrate smoothly over a billion years. For three of our resonant chains, about ~1% of the final configurations pass the four criteria to fit the Solar System. The most successful runs are obtained for systems formed in a cold PPD with a massive planetesimal disc. Conclusions. This work provides a fully consistent study of the dynamical history of the Solar System’s giant planets, from the protoplanetary disc phase up to the giant planet instability. Although building resonant configurations is difficult in low-viscosity discs, we find it possible to reproduce the Solar System from a cold, low-viscosity protoplanetary disc.

Voltage-induced modulation of interfacial ionic liquids measured using surface plasmon resonant grating nanostructures.

We have used surface plasmon resonant metal gratings to induce and probe the dielectric response (i.e., electro-optic modulation) of ionic liquids (ILs) at electrode interfaces. Here, the cross-plane electric field at the electrode surface modulates the refractive index of the IL due to the Pockels effect. This is observed as a shift in the resonant angle of the grating (i.e., Δϕ), which can be related to the change in the local index of refraction of the electrolyte (i.e., Δnlocal). The reflection modulation of the IL is compared against a polar (D2O) and a non-polar solvent (benzene) to confirm the electro-optic origin of resonance shift. The electrostatic accumulation of ions from the IL induces local index changes to the gratings over the extent of electrical double layer (EDL) thickness. Finite difference time domain simulations are used to relate the observed shifts in the plasmon resonance and change in reflection to the change in the local index of refraction of the electrolyte and the thickness of the EDL. Simultaneously using the wavelength and intensity shift of the resonance enables us to determine both the effective thickness and Δn of the double layer. We believe that this technique can be used more broadly, allowing the dynamics associated with the potential-induced ordering and rearrangement of ionic species in electrode-solution interfaces.

Development of surface plasmon resonance sensor utilizing GaSe and WS2 for ultra-sensitive early detection of dengue virus

This manuscript introduces highly sensitive surface plasmon resonance (SPR) sensor for early detection of the dengue virus. Through extensive optimization using MATLAB, the sensor architecture is meticulously constructed with a BK7 prism, Copper (Cu) layer, Gallium selenide (GaSe), Tungsten disulphide (WS2), and a sensing medium (SM) containing blood components (infected platelets and normal platelets) to ensure optimal performance. Use of WS2 emerges as a highly effective biomolecular recognition element (BRE) layer, leading to exceptional sensor capabilities. The proposed sensor achieves a peak sensitivity (S) of 303.28 (˚/RIU) and a resonance angle shift (∆θres.) of 10˚ specifically during the detection of infected platelets. Computational modeling using COMSOL Multiphysics validates the ability of the sensor to generate an intense electric field with a magnitude of 1.68×105 (V/m) and a penetration depth (PD) extending to 153.24 nm in the SM. This unique combination of PD and enhanced performance parameters positions the proposed SPR biosensor as a promising tool for the early-stage detection of the dengue virus.

Anisotropic Sensing Performance in a High-Sensitivity Surface Plasmon Resonance Sensor Based on Few-Layer Black Phosphorus.

Few-layer black phosphorus (FLBP) is a highly promising material for high sensitivity label-free surface plasmon resonance (SPR) sensors due to its exceptional electrical, optical, and mechanical properties. FLBP exhibits inherent anisotropy with different refractive indices along its two main crystal orientations, the zigzag and armchair axes. However, this anisotropic property is often overlooked in FLBP-based sensors. In this study, we conducted a comprehensive investigation of the SPR reflectivity and phase in a BK7-Ag-FLBP structure to understand the influence of the stacking sequence and the number of FLBP layers on the sensing performance. Clear resonant angle shifts caused by different stacking sequences of FLBP could be observed both theoretically and experimentally. In the theoretical study, the highest reflective and phase sensitivities were achieved with a 12-layer black phosphorus (BP) structure. The reflectivity sensitivity reached 287.9°/refractive index units (RIU) with the zz stacking 12-layer BP film exhibiting a sensitivity 76°/RIU higher than the ac stacking structure. Similarly, the phase sensitivity reached 1162°/RIU with the zz stacking 12-layer BP structure showing a sensitivity 276.9°/RIU higher than the ac stacking structure. The electric field distribution of the 12-layer BP structure with four different stacking sequences has also been analyzed. In the experiment study, the well-known Attenuated Total Reflection (ATR) θ-2θ SPR setup is utilized to detect the reflectivity and phase of BK7-Ag-FLBP structures. The FLBP samples with the same thickness but different stacking sequences show significant resonant angle shift (0.275°) and maximum phase difference variation (34.6°). The FLBP sample thickness and crystal orientations have been demonstrated using the angular-resolved polarized Raman spectroscopy (ARPRS). These theoretical and experimental results provide strong evidence that the stacking sequences of FLBP have a significant impact on the sensing performance of SPR sensors. By harnessing the anisotropic properties of materials like FLBP, novel structures of anisotropic-2D material-based SPR sensors could open up exciting possibilities for innovative applications.

Uricase biofunctionalized plasmonic sensor for uric acid detection with APTES-modified gold nanotopping

Current uric acid detection methodologies lack the requisite sensitivity and selectivity for point-of-care applications. Plasmonic sensors, while promising, demand refinement for improved performance. This work introduces a biofunctionalized sensor predicated on surface plasmon resonance to quantify uric acid within physiologically relevant concentration ranges. The sensor employs the covalent immobilization of uricase enzyme using 1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) and N-Hydroxysuccinimide (NHS) crosslinking agents, ensuring the durable adherence of the enzyme onto the sensor probe. Characterization through atomic force microscopy and Fourier transform infrared spectroscopy validate surface alterations. The Langmuir adsorption isotherm model elucidates binding kinetics, revealing a sensor binding affinity of 298.83 (mg/dL)−1, and a maximum adsorption capacity of approximately 1.0751°. The biofunctionalized sensor exhibits a sensitivity of 0.0755°/(mg/dL), a linear correlation coefficient of 0.8313, and a limit of detection of 0.095 mg/dL. Selectivity tests against potentially competing interferents like glucose, ascorbic acid, urea, D-cystine, and creatinine showcase a significant resonance angle shift of 1.1135° for uric acid compared to 0.1853° for interferents at the same concentration. Significantly, at a low uric acid concentration of 0.5 mg/dL, a distinct shift of 0.3706° was observed, setting it apart from the lower values noticed at higher concentrations for all typical interferent samples. The uricase enzyme significantly enhances plasmonic sensors for uric acid detection, showcasing a seamless integration of optical principles and biological recognition elements. These sensors hold promise as vital tools in clinical and point-of-care settings, offering transformative potential in biosensing technologies and the potential to revolutionize healthcare outcomes in biomedicine.

Highly sensitive detection of low-concentration sodium chloride solutions based on a gold-coated prism in Kretschmann setup

A gold-coated Kretschmann setup has been constructed and explored as a surface plasmon resonance (SPR) platform, specifically tailored for the detection of low-concentration sodium chloride (NaCl) solutions. The setup employs a BK7 prism coated with a 50 nm gold layer, serving as a plasmonic layer, to induce resonance. This resonance arises from the interplay between light waves and free electrons propagating at the interface of two media. The experimental findings reveal a notable resonance angle shift of 10° when the NaCl concentration is varied from 0 to 2.5 %. Furthermore, angle interrogation provides insightful details about the sensor's response to changes in the refractive index, showcasing a commendable sensitivity of 2400°/RIU, a high level of linearity at 0.9771, and an impressive resolution of 0.217 %. The demonstrated capabilities of this sensor underscore its potential for widespread applications, particularly in the monitoring of salt concentration across diverse domains such as seawater analysis, food processing, and fermentation processes. The robust performance and precision of this proposed sensor position it as a valuable tool with promising prospects for addressing the needs of various industries dependent on accurate salt concentration measurements.

Resonant chains in triple-planet systems

The mean motion resonance is the most important mechanism that may dominate the dynamics of a planetary system. In a multi-planetary system consisting of $N planets, the planets may form a resonant chain when the ratios of orbital periods of planets can be expressed as the ratios of small integers $T_1: T_2: :T_N=k_1: k_2: k_N$. Due to the high degree of freedom, the motion in such systems could be complex and difficult to depict. In this paper, we investigate the dynamics and possible formation of the resonant chain in a triple-planet system. We defined the appropriate Hamiltonian for a three-planet resonant chain and numerically averaged it over the synodic period. The stable stationary solutions -- apsidal corotational resonances (ACRs) -- of this averaged system, corresponding to the local extrema of the Hamiltonian function, can be searched out numerically. The topology of the Hamiltonian around these ACRs reveals their stabilities. We further constructed the dynamical maps on different representative planes to study the dynamics around the stable ACRs, and we calculated the deviation ($ of the resonant angle in the evolution from the uniformly distributed values, by which we distinguished the behaviour of critical angles. Finally, the formation of the resonant chain via convergent planetary migration was simulated and the stable configurations associated with ACRs were verified. We find that the stable ACR families arising from circular orbits always exist for any resonant chain, and they may extend to a high eccentricity region. Around these ACR solutions, regular motion can be found, typically in two types of resonant configurations. One is characterised by libration of both the two-body resonant angles and the three-body Laplace resonant angle, and the other by libration of only two-body resonant angles. The three-body Laplace resonance does not seem to contribute to the stability of the resonant chain much. The resonant chain can be formed via convergent migration, and the resonant configuration evolves along the ACR families to eccentric orbits once the planets are captured into the chain. Ideally, our methods introduced in this paper can be applied to any resonant chain of any number of planets at any eccentricity.

The nature of the Laplace resonance between the Galilean moons

The Laplace resonance is a mean-motion resonance that involves the three inner Galilean moons of Jupiter. However, its true nature is in part unclear; in particular, different views can be found in the literature on whether the Laplace resonance is a pure three-body resonance or a mere superposition of two-body resonances. To settle this question, we conduct a thorough analysis of the many resonances involved, starting from the two-body 2:1 commensurabilities of the couples Io–Europa and Europa–Ganymede, and ending with the three-body 4:2:1 commensurability between the three moons. By artificially varying the parameters of the system and monitoring its fundamental frequencies, we cartography all resonances involved and their interactions. From the analysis of the individual 2:1 commensurabilities, we find that despite the oscillation of the resonant angles they are not genuine resonances, as the trajectory of the system in the phase space is not enclosed by separatrices. On the contrary, as suggested by previous works, we show that the only current true mean-motion resonance is the pure three-body resonance between all three satellites. Moreover, we find that the current values of the moons’ orbital elements make the Laplace resonance sufficiently separated from the individual two-body 2:1 resonances, preventing chaotic effects from appearing.

Why the Laplace Resonant Angle is So Special

We analyze adjacent local pairs of mean-motion resonances (MMRs) between three orbiting bodies designed to produce a Laplace resonant phase angle φ L or one of its multiples N φ L, where integer N ≥ 2. This assumption yields a concrete pattern of Laplace resonances, very few of which (with angles φ L and 2φ L) have been observed in actual (extra)solar subsystems. All other MMRs face issues of proximity or remoteness of the orbits (they are too close or too far apart). We highlight one as yet unobservable MMR in each N-sequence for which these issues appear to be less acute.

Ultra-high order mode-assisted optical differentiator for edge detection with high tunability

An optical spatial differentiator based on the photonic spin Hall effect (PSHE) with high tunability is presented. By utilizing the characteristics of ultra-high order modes in the symmetrical metal cladding waveguide, the Fresnel reflection coefficient spectrum exhibits a narrow peak width and low trough at the resonant incident angles, resulting in high sensitivity to changes in the incident angle-induced spatial shift caused by the PSHE (the highest ∂(|r s /r p |)/∂θ value can reach 107). After polarization transformation and extinction, the output field demonstrates differential operation with respect to the input field. When applied to edge detection, our differentiator can achieve tunable resolution edge images by adjusting the incident angle. Our proposed edge detection scheme has potential applications for cellular and molecular imaging through two-dimensional extension via the target rotation.

Polarization Property Associated with Surface Plasmon Resonance in a Palladium Thin-Film Coated Aluminum Grating in a Conical Mounting and Its Application to Hydrogen Gas Detection.

We have investigated a polarization property of the (specularly) reflected light from an aluminum grating, coated with a palladium (Pd) thin-film on its surface. The polarization property, which is associated with surface plasmon resonance (SPR), and occurs in the Pd thin-film on the aluminum grating in a conical mounting, is observed as a rapid change in the normalized Stokes parameter s3, around the resonance angle, θsp, at which point, SPR occurs. The sensing technique used the rapid change in s3 to allow us to successfully detect a small change in the complex refractive index of the Pd thin-film layer upon exposure to hydrogen gas, with a concentration near the lower explosion level. Experimental results showed that the sensing technique provided a sensitive and stable response when the Pd thin-film layer was exposed to gas mixtures containing hydrogen at concentrations of 1 to 4% (by volume) in nitrogen.

Surface exciton polariton enhanced Goos-Hänchen and Imbert-Fedorov shifts and their applications in refractive index sensing.

The spatial and angular Goos-Hänchen shifts (GHSs) and Imbert-Fedorov shifts (IFSs) are theoretically investigated in a modified Kretschmann-Raether configuration consisting of glass prism, J-aggregate cyanine dye, and air. With the excitation of surface excitation polaritons (SEPs), the spatial and angular GHSs and IFSs for the transverse magnetic polarized light are strongly enhanced around the resonant angle of SEP. A highly sensitive gas sensor based on the SEP enhanced GHS (or IFS) is proposed, which exhibits the refractive index sensitivity on the order of 106λ/RIU (or 105λ/RIU) (λ: illumination wavelength; RIU: refractive index unit) for the GHS- (or IFS-) based gas sensor, respectively.

The structural properties of full-length annexin A11.

Annexin A11 (ANXA11) is a calcium-dependent phospholipid-binding protein belonging to the annexin protein family and implicated in the neurodegenerative amyotrophic lateral sclerosis. Structurally, ANXA11 contains a conserved calcium-binding C-terminal domain common to all annexins and a putative intrinsically unfolded N-terminus specific for ANXA11. Little is known about the structure and functions of this region of the protein. By analogy with annexin A1, it was suggested that residues 38 to 59 within the ANXA11 N-terminus could form a helical region that would be involved in interactions. Interestingly, this region contains residues that, when mutated, may lead to clinical manifestations. In the present study, we have studied the structural features of the full-length protein with special attention to the N-terminal region using a combination of biophysical techniques which include nuclear magnetic resonance and small angle X-ray scattering. We show that the N-terminus is intrinsically disordered and that the overall features of the protein are not markedly affected by the presence of calcium. We also analyzed the 38-59 helix hypothesis using synthetic peptides spanning both the wild-type sequence and clinically relevant mutations. We show that the peptides have a remarkable character typical of a native helix and that mutations do not alter the behaviour suggesting that they are required for interactions rather than being structurally important. Our work paves the way to a more thorough understanding of the ANXA11 functions.

Upstream motion of chorus wave generation: comparisons with observations

An understanding of the development of strong very low frequency chorus elements is important in the study of the rapid MeV electron acceleration observed during radiation belt recovery events. During such events, chorus elements with long-duration (20–40 ms), strong (|Bw| 0.5–2.0 nT) subpackets with smoothly varying frequency and phase capable of producing nonlinear energy gain of 1%–2% for multi-MeV seed electrons. For such strong chorus elements, we examine the consequences of an upstream motion of the chorus wave generation region using Van Allen Probes observations and nonlinear theory. For a given upstream velocity, vs, resonant electron energy (50–350 keV) and pitch angle (105–115 deg) are uniquely determined for each wave frequency. We examine the effect of an upstream vs on the inhomogeneity factor that controls wave growth. For steadily increasing upstream motion as the chorus element evolves, vs/c ranging over [-0.001, −0.065], nonlinear wave growth takes place at ≥ 50% of the theoretical maximal value during the development of the observed strong subpackets. For the cases examined, resonant electron energies and pitch angles closely match those of the observed injected electron flux enhancements responsible for chorus development and the nonlinear acceleration of MeV radiation belt electrons.

Sensing performance enhancement of plasmonic waveguide sensor using a bimodal strategy with digital Gaussian filter

In this paper, a novel bimodal strategy with digital Gaussian filter was proposed to improve the sensing performance of plasmonic waveguide sensor (PWG). The central angle of the bimodal spectrum is adopted rather than the traditional resonance angle. Compared with conventional noise reduction algorithm, the proposed digital Gaussian filter would transform resonance dip into bimodal spectrum and then improve both sensitivity and signal-to-noise ratio. Expected angle and FWHM (full width at half maximum) of Gaussian filter are two significant parameters to optimize sensing performance for each specific waveguide spectrum. The sensitivity and standard deviation of TM1 mode were measured as 90.715 deg/RIU and 7.515 × 10−5 deg, respectively, which are better than those of TM1 PWG sensor. Its RI resolution was then calculated to be 8.28 × 10−7 RIU, which is double-fold lower than that of TM1 PWG sensor, that is 1.73 × 10−6 RIU. For biosensing application, the limit of detection (LOD) of 29.15 mg/L, that is 0.16 mM, was obtained for glucose molecule, according to the three-fold standard deviation theory. For BSA detection, the LOD as high as 0.949 pM was achieved, which is approximately 2.8-fold lower than that of PWG sensor. It is also nearly two orders of magnitude lower than that of gold based SPR sensor, which is 91.33 pM.