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

TL;DR

This paper presents an optimized metal-dielectric metasurface sensor with microresonators for highly sensitive detection of IgG protein concentrations in solutions, combining experimental measurements and numerical modeling.

Contribution

It introduces a novel metasurface unit cell design optimized for IgG detection, enhancing sensor sensitivity through geometric adjustments based on experimental permittivity data.

Findings

The metasurface with four copper microresonators showed maximum sensitivity.

Frequency shifts correlated with IgG concentration changes.

Calibration graph enables accurate concentration determination.

Abstract

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.