Metamaterial Inspired RF Planar Sensor for Dielectric Characterization and Identification of Adulteration in Vegetable Oils

A low cost RF planar sensor for dielectric characterization and detection of adulteration in vegetable oils is proposed in this paper. The resonance characteristics of the metamaterial inspired sensor vary with the change in electrical properties of the liquid sample in contact. The sensor is designed to operate in 2.4 GHz ISM band and fabricated on a FR4 substrate of thickness 1.6 mm. A numerical model based on finite element method is developed to extract the relative permittivity of test samples. The sensor is experimentally validated by testing different vegetable oils and comparing the measurement results with values available in literature. As a proof of concept, the prototype is tested for adulteration in vegetable oils with different concentration of adulterant oil and their presence has successfully identified. The compactness, ease of fabrication and low manufacturing cost allow the planar sensor to be considered as promising alternative for dielectric characterization and detection of adulteration in vegetable oils. Moreover, the single port topology of the sensor allows direct submersion in the liquid samples and it also distinguishes materials of close permittivity.