Broadside coupled split ring resonator metamaterial structure for sensitive measurement of liquid concentrations

Abstract

This paper describes a simple and quick method to determine the concentrations of aqueous solutions using a Broad Side Coupled Split Ring Resonator (BCSRR) metamaterial structure operating at microwave frequencies. A capillary tube is placed between the symmetrically arranged BCSRR rings fabricated on two separate strips of the same substrate in such a way that the sample comes along the split-gap of the rings where the field concentration is maximum. As the sample liquid enters to the capillary tube, a resonance frequency shift is observed with respect to the variation in concentration. Resonance frequency shifts of the BCSRR due to varying concentrations (0-2 M) of Sodium Chloride (NaCl) and Potassium Chloride (KCl) solutions are measured using Vector Network Analyser (VNA) by arranging the transmitting and receiving probes of the VNA on the two sides of the BCSRR test setup.