Novel Sensors Based on the Symmetry Properties of Split Ring Resonators (SRRs)

Jordi Naqui,Miguel Durán-Sindreu,Ferran Martín

doi:10.3390/s110807545

Jordi Naqui, Miguel Durán-Sindreu + Show 1 more

Open Access

https://doi.org/10.3390/s110807545

Copy DOI

Abstract

The symmetry properties of split ring resonators (SRRs) are exploited for the implementation of novel sensing devices. The proposed structure consists of a coplanar waveguide (CPW) loaded with movable SRRs on the back substrate side. It is shown that if the SRRs are placed with the slits aligned with the symmetry plane of the CPW, the structure is transparent to signal propagation. However, if the symmetry is broken, a net axial magnetic field can be induced in the inner region of the SRRs, and signal propagation is inhibited at resonance. The proposed structures can be useful as alignment sensors, position sensors and angle sensors. This novel sensing principle is validated through experiment.

Highlights

Split ring resonators (SRRs) consist of a pair of concentric metallic rings, etched on a dielectric substrate, with slits etched on opposite sides
Sensors 2011, 11 due to the presence of the split ring resonators (SRRs)
Let us consider, instead, that only one SRR is etched in the back substrate side of a coplanar waveguide (CPW) structure, and that the slit of each ring is perfectly aligned with the symmetry plane of the CPW structure [see

Summary

Introduction

Split ring resonators (SRRs) consist of a pair of concentric metallic rings, etched on a dielectric substrate, with slits etched on opposite sides (see Figure 1). SRRs have been coupled to planar transmission lines, for the synthesis of transmission line metamaterials It was demonstrated in [4] that a coplanar waveguide (CPW) loaded with pairs of SRRs in the back substrate side inhibits signal propagation in the vicinity of SRR resonance, and this was interpreted as due to the negative effective permeability of the structure. Different kind of sensors based on SRRs have been proposed, such as thin-film sensors [7], particle detectors [8,9], stress sensors [10], moisture sensors [11], pressure sensors [12], or displacement sensors [13], among others In most of these applications, the variation of the resonance frequency or the quality factor of the particles, caused by changes in the variable to be sensed, has been the considered sensing strategy.

The Sensing Principle

Validation

Experimental Results

Conclusions