Double negative (DNG) square-enclosed C.S.R.R. metamaterial for liquid sensing applications with high sensitivity

This study proposes a square enclosed circular split ring resonator constructed metamaterial absorber for detecting oils and fuels. This structure measures $20 \times 20 \mathrm{~mm}^{2}$ and was simulated using CST Microwave Studio software. The design incorporates an FR4 substrate sandwiched between two copper layers. The absorption values for this suggested MTM structure are $\mathbf{9 9. 3 7 \%}$ at $10.5 \mathrm{GHz}, \mathbf{9 9. 9 3 \%}$ at $15.57 \mathrm{GHz}, \mathbf{9 6 \%}$ at 17.31 $\mathrm{GHz}, \mathbf{9 9. 2 1 \%}$ at 19.74GHz, and $97.21 \%$ at 20.52GHz. The sensor has a q-factor of 378.59, the highest sensitivity(S%) is 4.15, and the figure of merit(FOM) value is 15.71, which indicates that this sensor can perform well and effectively. In addition to this, this MMA produces a higher sensitivity while detecting different fuels and oils. The compact size, high absorbance, and high sensitivity make it suitable for using this MMA in various microwave applications, including oil, fuel, and microfluidics industries.