Structural, Morphological, Electrical, Magnetic, and dielectric properties of Zn0.5-xCa0.1Co0.4+xFe2O4 through the sol-gel method for flexible substrates in food chemical sensing

Food safety is a critical public health priority, as food chemicals such as formalin, saccharin, sucralose, and sodium benzoate present a significant health threat. A flexible substrate based on Zn-Ca-Co ferrite is proposed as a solution to food safety concerns, addressing limitations found in conventional microwave sensors. This study explores the possibilities of Zn0.5-xCa0.1Co0.4+xFe2O4 (x ranging from 0 to 0.30) nanoparticles synthesized by sol-gel as a flexible substrate, and a modified labyrinth-shape metamaterial structure reveals mu-negative characteristics from 7.084 to 7.48 GHz. The dielectric constant varied with composition, generating values of 1.34 to 1.84 for x values of 0.0 to 0.3. The sensor's performance is assessed at various concentrations for each analyte, showing a clear link between chemical concentration and sensor response. The resonant frequency shift decreased as the analyte concentration increased, with formalin shifting from 110 MHz at 5% to 40 MHz at 20% and saccharin from 470 MHz at 25 % to 210 MHz at 33 % with notable sensitivity, ranging from 0.56 % to 7.01 %. The perceptible novelty of this study is that it introduces Zn-Ca-Co ferrite nanoparticles with enhanced magnetic and dielectric properties, designed for microwave sensing, and integrated into a flexible, mu-negative metamaterial for food safety applications.