arXiv subjects

Z. E. Eremenko

Publications and source records attributed to Z. E. Eremenko.

6 recordsLinked to original sources

arXiv2026

Optimization of the metal-dielectric metasurface unit cell for sensitivity enhancement in determination of IgG concentration in solutions

This study focuses on developing a metal-dielectric sensor structure with optimized unit cell geometry for determination of protein Immunoglobulin G (IgG) concentration in aqueous solutions. The research combines both experimental and theoretical investigations, utilizing the differential microwave dielectrometry method and numerical modeling with COMSOL software. Complex permittivity (CP) values dependence of IgG water solutions on the protein concentration was experimentally obtained at the microwaves using original microwave dielectrometer setup. It was shown that increase of IgG concentration resulted in the CP values of the solutions studied decrease. The experimentally obtained CP data for the IgG water solutions were used as a basis for microwave metal-dielectric metasurface unit cell numerical modeling. The metal-dielectric metasurface consisting of Teflon substrate and plane copper microresonators was combined with a standard 96-well microplate used in clinical laboratories. Optimization of the obtained metasurface unit cell revealed that the size and position of the copper microresonators within the unit cell significantly impact the sensor sensitivity for determining the IgG concentration in aqueous solutions. The metasurface with the unit cell containing four copper microresonators provided the most sensitive platform for detecting variations in the IgG concentration in the sample. The frequency shift of the reflection coefficient was directly related to changes in the protein concentration. The calibration graph was developed for effective determination of IgG concentrations in the aqueous solutions.

physics.optics↗

arXiv2026

Terahertz metasurface sensor with graphene microstrips for biosensing: modeling and application

The study is devoted to development and optimization of a metasurface-based sensor with graphene constituents for potential biosensing applications. A unit cell of the proposed metasurface consists of a thin flexible dielectric substrate layer with a centrally positioned graphene microstrip. As a result of numerical modeling of spectral properties of the metasurface by COMSOL Multiphysics software in terahertz range from 5 to 35 THz the absorption spectrum maxima (resonance modes) are revealed. The following stages of the study demonstrate that placement of a layer of tested liquid sample (water or Bovine Serum Albumin (BSA) solution) on the metasurface causes a low frequency shift of the plasmonic resonance mode chosen for biosensing measurements. This frequency shift, along with the change in the amplitude of the absorption peak, are highly sensitive to the refractive index of the tested liquid sample. The obtained results demonstrate the potential of the developed metasurface-based sensor with graphene microstrips for application as a sensing structure to determine proteins and other biomolecules in liquid samples.

physics.optics↗

arXiv2020

A method of effective potentials for calculating the frequency spectrum of eccentrically layered spherical cavity resonators

A novel method for the calculation of eigenfrequencies of non-uniformly filled spherical cavity resonators is developed. The impact of the system symmetry on the electromagnetic field distribution as well as on its degrees of freedom (the set of resonant modes) is examined. It is shown that in the case of angularly symmetric cavity, regardless of its radial non-uniformity, the set of resonator modes is, as anticipated, a superposition of TE and TM oscillations which can be described in terms of a single scalar function independently of each other. The spectrum is basically determined through the introduction of effective ``dynamic'' potentials which encode the infill inhomogeneity. The violation of polar symmetry in the infill dielectric properties, the azimuthal symmetry being simultaneously preserved, suppresses all azimuthally non-uniform modes of electric-type (TM) oscillations. In the absence of angular symmetry of both electric and magnetic properties of the resonator infill, only azimuthally uniform distribution of both TM and TE fields is expected to occur in the resonator. The comparison is made of the results obtained through the proposed method and of the test problem solution obtained with use of commercial solvers. The method appears to be efficient for computational complex algorithms for solving spectral problems, including those for studying the chaotic properties of electrodynamic systems' spectra.

cond-mat.dis-nn↗

arXiv2018

The spectrum of non-centrosymmetrically layered spherical cavity resonator. I.The mode decomposition method

We develop a theoretical method for solving Maxwell's equations to obtain the frequency spectra of inhomogeneous and asymmetric cavity resonators using a couple of effective Debye-type potentials. The structure we study specifically is the layered spherical cavity resonator with symmetrically or asymmetrically inserted inner dielectric sphere. The comparison of the exact numerical results obtained for the frequency spectrum of layered cavity resonator with centrosymmetrically inserted sphere and the spectrum found from the suggested theory reveals good agreement at the initial part of the frequency axis. The coincidence accuracy depends on the number of trial resonant modes that we use while approving our method numerically.

physics.comp-ph↗

arXiv2008

The Effect of Random Surface Inhomogeneities on Microresonator Spectral Properties: Theory and Modeling at Millimeter Wave Range

The influence of random surface inhomogeneities on spectral properties of open microresonators is studied both theoretically and experimentally. To solve the equations governing the dynamics of electromagnetic fields the method of eigen-mode separation is applied previously developed with reference to inhomogeneous systems subject to arbitrary external static potential. We prove theoretically that it is the gradient mechanism of wave-surface scattering which is the highly responsible for non-dissipative loss in the resonator. The influence of side-boundary inhomogeneities on the resonator spectrum is shown to be described in terms of effective renormalization of mode wave numbers jointly with azimuth indices in the characteristic equation. To study experimentally the effect of inhomogeneities on the resonator spectrum, the method of modeling in the millimeter wave range is applied. As a model object we use dielectric disc resonator (DDR) fitted with external inhomogeneities randomly arranged at its side boundary. Experimental results show good agreement with theoretical predictions as regards the predominance of the gradient scattering mechanism. It is shown theoretically and confirmed in the experiment that TM oscillations in the DDR are less affected by surface inhomogeneities than TE oscillations with the same azimuth indices. The DDR model chosen for our study as well as characteristic equations obtained thereupon enable one to calculate both the eigen-frequencies and the Q-factors of resonance spectral lines to fairly good accuracy. The results of calculations agree well with obtained experimental data.

cond-mat.mes-hall↗

arXiv2006

Influence of Random Bulk Inhomogeneities on Quasi-Optical Cavity Resonator Spectrum

We suggest the statistical spectral theory of oscillations in quasi-optical cavity resonator filled with random inhomogeneities. It is shown that inhomogeneities in the resonator result in intermode scattering leading to the shift and broadening of spectral lines. The shift and broadening of each line essentially depends on frequency distance to adjacent spectral lines. With increasing the distance the influence of inhomogeneities sharply reduces. The solitary spectral lines which have the distance to the nearest lines quite large is slightly changed due to small inhomogeneities. Owing to such selective influence of inhomogeneities on the spectral lines the effective spectrum rarefaction appears. Both the shift and broadening of spectral lines as well as spectrum rarefaction in quasi-optical cavity millimeter wave resonator were detected experimentally. We found out that inhomogeneities result in stochastization of the resonator spectrum in that mixed state appears, i.e. the spectrum acquires both regular and random parts. The active self-oscillator system based on the inhomogeneous quasi-optical cavity millimeter wave resonator with Gunn diode was studied as well. The inhomogeneous quasi-optical cavity millimeter wave resonator (passive and active) can serve as a model of semiconductor quantum billiard. Based on our results we suggest using such billiards with spectrum rarefied by random inhomogeneities as an active system of semiconductor laser.

cond-mat.dis-nn↗