Fabrication of mm-Scale Complementary Split Ring Resonators, for Potential Application as Water Pollution Sensors

Abstract

Rectangular, millimeter-scale complementary split ring resonators were fabricated, employing the so-called Computer Numerical Control method, combined with a home-built mechanical engraver. Their electromagnetic performance was thoroughly investigated with respect to their dimensions in the frequency regime between 2 and 9 GHz via combining experiments and corresponding theoretical simulations, wherein a considerably effective consistency was obtained. Moreover, their sensing response was extensively investigated against various aqueous solutions enriched with typical fertilizers used in agriculture, as well as detergents commonly used in every-day life. Corresponding experimental results evidently establish the capability of the studied metasurfaces as potential sensors against water pollution.

Engraved Split-Ring Resonators as Potential Microwave Sensors for Olive Oil Quality Control

“…Particularly, metasurfaces were measured using a combination of a P9372A Vector Network Analyzer (VNA) (Keysight, California, USA; frequency range: 300 kHz–9 GHz) and waveguides WR284 (2.4–4.8 GHz), WR187 (3.5–7 GHz), and WR137 (5–10 GHz) (Figure c), so that a frequency range of 2–9 GHz was covered. Details regarding the setup and the measurement procedure were previously described. ,, Two different configurations were investigated, i.e., the CSRR is oriented so that the electric field component is parallel (TE orientation, drawing in Figure a) and perpendicular to the gap (TM orientation, drawing in Figure c).…”

“…Moreover, such resonant behavior has been previously shown for those CSRRs. 56 Consequently, all investigated CSRRs exhibit considerable electromagnetic behavior.…”

“…62,63 On the other hand, Raman experiments were conducted at room temperature using a LabRAM HR Evolution confocal Raman microscope (LabRAM HR; Horiba France SAS, Lille, France); experimental details are described in the literature. 56 Processing and analysis of the acquired raw Raman spectra were achieved through the instrument's original software (LabSpec, version LS6; Horiba, Lille, France). Initially, smoothing under a Gaussian filter with a kernel of five points (denoise at 5) was used, where cosmic rays were removed, and the background was removed using a baseline correction at the sixthorder polynomial function.…”

“…Details regarding the setup and the measurement procedure were previously described. 55,56,60 Two different configurations were investigated, i.e., the CSRR is oriented so that the electric field component is parallel (TE orientation, drawing in Figure 2a) and perpendicular to the gap (TM orientation, drawing in Figure 2c).…”

“…On the other hand, the fabrication of metasurfaces employing the CNC method has been recently reported . CNC milling is a subtractive fabrication process that uses rotating cutting tools to remove material from a starting stock piece, commonly referred to as the workpiece.…”