Split-ring resonator-based sensor for thin-film sensing applications

A Split-Ring Resonator (SRR) based sensor for the detection of solid thickness is proposed. The structure is composed by a host microstrip transmission line loaded with two SRRs. The sensing principle is based on the detection of the notch introduced by the SRR in the transmission coefficient between the two ports of the microstrip line. Thus, a frequency shift of the notch in the transmission coefficient is related to a change in the effective permittivity of the structure when the sensor is covered with a solid. A complete characterization of the sensor is performed through simulations, thanks to a wide analysis of materials with different permittivity and thickness. Finally, the simulated results are corroborated with measurements.