Split ring resonators in microwave regime for sensing of reagents in aqueous solutions

Abstract

In this thesis, design, fabrication, and characterization of different microwave band split ring resonator-based sensors used for sensing of glucose in aqueous solu tions are presented. Following an introduction to metamaterials and split ring res onators, a literature survey of their applications in sensing is given. After this, an analytical model that describes the operation of a single loop SRR is demonstrated along with additional theoretical considerations. Exploratory work in which simulated and measured electromagnetic interaction of different split ring resonator geometries with dielectric loads is reported. Change of resonance characteristics of the split ring resonator is shown to be correlated with different dielectric loads, such as aqueous glucose solutions of different concentrations. After the exploratory work, a biosensor application incorporating a glucose specific element glucose oxidase immobilized in a PEDOT:PSS matrix is discussed. The biosensor application had a sensitivity of 0.107 MHz/mg mL−1 to glucose. Its specificity was demonstrated by comparison of its re sponse to other reagents, such as sucrose, fructose, and NaCl. Precision, linearity, and repeatability improvements to this design was done by adoption of conceptual develop ments by switching to a differential measurement scheme, use of loop antennas instead of monopole antennas, and incorporation of microfluidic elements to the system. An improved iteration of the original sensor system was presented at the end, fabricated from materials highly compatible with relevant biosensor applications.