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

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.

Two‐dimensional displacement and alignment sensor based on reflection coefficients of open microstrip lines loaded with split ring resonators

“…This has arisen because of the subwavelength dimensions, high quality factor resonance and sensitivity of the resonance characteristics of these elements to their physical dimensions and constituent materials. Various types of displacement and rotation sensors based on variation of resonance frequency, quality factor and notch depth in the transmission spectrum of SRR-loaded transmission lines (TLs) have been proposed in the literature [1,5,6,7,8]. The concept was also extended for the design of two-dimensional displacement sensors [9,10].…”

Two-dimensional alignment and displacement sensor based on movable broadside-coupled split ring resonators

“…However, due to their sub-wavelength dimensions, metamaterial fundamental elements such as split ring resonators (SRRs), have also found applications in the design of compact one-and two-dimensional planar circuits such as filters [4,5,6,7,8,9,10], couplers [11,12,13,14,15], and antennas [16,17,18], or to improve the performance of these components [19,20]. It has been also shown that due to the high quality factor, subwavelength dimensions, and the localized sensitivity of the resonance to the constituent materials and physical dimensions, SRRs can be used in the design of high sensitivity and high resolution sensors [21,22,23,24,25,26,27,28], or to enhance the sensitivity of the conventional sensors [29].…”

Analysis of transmission lines loaded with pairs of coupled resonant elements and application to sensors

“…Moreover, orthogonal orientation between the symmetry plane of the CPW and the symmetry plane of the pair of SRRs is considered. Although for the implementation of metamaterial transmission lines the pairs of SRRs are implemented with identical resonators, disruption of symmetry may be of interest in certain applications, such as sensors and comparators based on symmetry properties [31]. Therefore, we will consider the more general case of CPWs with asymmetric SRR loading (i.e., with different SRRs forming the pair, including different inductive coupling between the line and the resonators).…”