Structural, morphological, optical and electrical properties of ferrite-based nanoparticles synthesized flexible substrate for chemical sensing application

A compact Ca_xCo_(0.90-x)Zn_0.10Fe₂O₄ based nanoparticles synthesized flexible microwave substrate with single negative (SNG) metamaterial is being successfully fabricated for industrial chemical contamination sensing applications. The unit cell dimensions of the MTM are 0.114λ × 0.114 λ × 0.017 λ. The nanoparticles, derived from the Ca_xCo_(0.90-x)Zn_0.10Fe₂O₄ material with varying Ca concentrations (Ca25, Ca50, and Ca75), have been synthesized using a sol-gel method, and their structural, morphological, and dielectric properties have been comprehensively characterized. Dielectric constants and loss tangents have been measured over the frequency range of 2–20 GHz. Simulation of the S₂₁ response at 3.43 GHz, 6.50 GHz, 11.49 GHz, and 16.46 GHz has yielded maximum magnitudes of −52.78 dB, −48.07 dB, −52.16 dB, and −39.37 dB, respectively. Experimental verification on an FR-4 rigid substrate at 3.28 GHz, 6.58 GHz, 11.76 GHz, and 16.33 GHz has revealed magnitudes of −25.67 dB, −24.56 dB, −31.13 dB, and −25.17 dB. Finally, when fabricated on the flexible microwave substrate, the MTM displayed S21 responses of −48.31 dB, −43.12 dB, −61.80 dB, and −24.70 dB at 3.19 GHz, 6.62 GHz, 11.58 GHz, and 16.65 GHz, respectively. The MTM has exhibited SNG properties in distinct frequency bands and near-zero index (NZI) characteristics. The sensitivity, figure of merit (FOM), and Q-factor have been achieved at 0.096 GHz/RIU, 0.152 GHz/RIU, 0.846 (RIU⁻¹), 0.846 (RIU⁻¹), and 8.430, 29.801, respectively. Its performance has been validated through simulation, VNA measurements, and advanced design system (ADS) software analysis, showcasing promise for diverse applications in S-, C-, X-, and Ku-bands. The anticipated structure performs well in terms of its small size, flexibility, sensitivity, and lightweight, making it suitable for wireless communications and methanol and ethanol contamination sensing in industrial applications.