Thin-film sensing using circular split-ring resonators at mm-wave frequencies

In this paper, we investigate a thin-film sensing approach using split-ring resonators. The sensitivity based on tuned magnetic resonance has been demonstrated using three methods: by depositing the film in the gap, under the rings as an intermediate layer and on the rings as an overlayer. The numerical simulations and experimental results are presented. In addition, the advantages and the limitations of each approach are discussed. Moreover, the sensitivity of the circular rings are compared with that of the square rings.