Square Split-Ring Resonator as a Sensor for Detection of Nanoparticles in PVDF-Based Nanocomposites at Ultra-High Frequencies: MXenes and MoS2 Concentrations

The performance of a printed square split-ring resonator as a sensor for quantifying nanoparticle concentrations in PVDF-based nanocomposites was evaluated at UHF frequencies. The sensing mechanism was based on the frequency response of parameter S₂₁, observing the shift in the resonant frequency and a variation in S₂₁ level, while samples were placed on the ring split and compared to the sensor without a sample. Experiments with samples of PVDF-based nanocomposites combined with different concentrations of both MoS₂ and MXenes, ranging from 0.01% to 0.2%, were conducted. In general, considering both types of samples studied, it was observed that, as the concentration increases, S₂₁ (dB) increases from -6.35 to -6 dB. At the same time, the resonance frequency in the S₂₁ plot went from 500.4 to 498.25 MHz. Although the concentrations and their variations were relatively low, shifts in the resonance frequency of S₂₁ were evident, demonstrating the ability of the sensor to detect low concentrations and variations of MoS₂ and MXenes, being the detection of samples with higher concentrations feasible as future work, and concluding that the sensor had a relatively acceptable performance. In this study, MXenes were the concentrations that produced more noticeable shifts in the resonance frequency of S₂₁. Likewise, characterizations based on SEM and TEM were performed to corroborate the ones at UHF frequencies.