Enhanced Permittivity Measurement Using a High-Sensitivity Microwave Sensor Based on Split Ring Resonators

In this paper, a low profile and high sensitivity metamaterial microwave sensor for dielectric materials characterization is presented. The proposed sensor consists of one split ring resonator (SRR) in microstrip technology, printed on Rogers 5880 substrate. The SRR is placed between two microstrip line instead of indirect coupling which concentrate the electric field in the sensing area, hence increasing the sensitivity. The sensing mechanism is based on measuring the change of the minimum transmission frequency produced by different dielectric properties of the loaded materials under test (MUTs). This proposed design exhibits a high sensitivity close to 54 % as the relative permittivity of MUTs changes from 1 to 10. To the best of authour's knowledge, this is the highest sensitivity obtain up to now using SRR based sensor. The permittivity derivation is validated experimentally by measuring well known materials, specially Polylactic acid (PLA), FR-4 epoxy and ROTMMI0i. The developed sensor is cost effective and can be suitable for several applications including nondestructive, microfluidics and biomedical sensors.