Low-Cost Microwave Sensor for Characterization and Adulteration Detection in Edible Oil

Featured Application: Characterization of liquids especially edible oils and adulteration detection using dielectric spectroscopy. A low-cost microwave sensor was designed for oil adulteration detection and characterization of pure edible oil using dielectric spectroscopy. The sensor’s final design was fabricated on a low cost 1.6 mm thick FR-4 substrate with a combination of a complementary split ring resonator and a transmission line. The sensor’s dimensions were 35 × 30 × 1.6 mm³ with a substrate dielectric constant of 4.3. A 5.25 GHz resonance frequency was selected as a reference for characterization and adulteration detection in pure edible oil. Initially, pure olive, caster, flaxseed, and mustard oil were characterized by the design sensors, with frequency shifts of 250, 370, 150, and 320 MHz, respectively. Pure olive oil with adulteration of castor, mustard, and argemone oil, was tested by placing the samples directly on the sensor. The experimental results showed that the sensor can detect 10% to 30% adulteration in the olive oil. The maximum sensitivity, frequency shift and quality factor were noted as 4.6, 530 MHz and 39, respectively. The high values of sensitivity and quality factor, along with agreement between simulated and experimental results, makes our sensor a good candidate for oil characterization and adulteration detection.