A novel miniaturized asymmetric CPW split ring resonator with extended field distribution pattern for sensing applications

Abstract

Novel modified split-ring resonator (SRR) for expanded field distribution and miniaturized dimensions for sensing with double sided detection capability is proposed. The proposed design is based on an asymmetric coplanar waveguide type SRR and demonstrate a smaller radius of 0.035 × λ with a resonance of 1.57 GHz at its first harmonic. The proposed structure has the potential of higher sensitivity, requires smaller sample volume and is miniaturized compared to the conventional ring resonators. The long but narrow overlap gaps evident in the proposed miniaturized SRR create capacitive and inductive contributions for better sensing performance regime and optimized for superior efficiency and miniaturization capability. For sensitivity evaluation, a coplanar SRR prototype operating at the same resonance is compared with the proposed miniaturized coplanar SRR to underscore its superior performance profile. The resulting design is prototyped on RO3003 microwave laminate with dielectric permittivity (ℇr) of 3 and measured. Sensitivity analysis is conducted by loading the both resonator on both planes with Teflon cladding sample of permittivity of 2.33, thickness of 3 mm and the results are compared. The final design is validated by loading the proposed resonator with a 0.05λ × 0.05λ sq.m and a strip of 0.045λ × 0.015λ sq.m moisture-responsive commercially available 3 M transparent water-soluble wave solder tape 5414 Poly-vinyl alcohol (PVA) film having a thickness of 20 μm.