A dual-mode microwave sensor for edible oil characterization using magnetic-LC Resonators

• A low-cost, compact, and high sensitivity dual-mode microwave sensor is reported. • The complex permittivity of oils to be tested can be extracted by using HFSS. • The estimation error of dielectric constant is less than 0.28%. • The sensor sensitivity is up to 9.9%. A low-cost, compact, and high sensitivity dual-mode microwave sensor for edible oil determination and quality monitoring is proposed in this paper. Two magnetic-LC (MLC) resonators loaded on a flared microstrip patch are fabricated on a Rogers RT/Duroid 5880 substrate. The dual-mode microwave sensor is designed and measured to operate at 12.6 GHz and 16.2 GHz. When the proposed dual-mode microwave sensor is submerged in the oils to be tested, the changes of resonance frequency and peak attenuation are utilized for sample identification and dielectric characterization. The complex permittivity of oils under test are extracted by building an approximate model in High Frequency Structure Simulator (HFSS). Two simplified linear equations are established to estimate the complex permittivity of unknown oils and heated peanut oil samples. The estimated error of dielectric constant is less than 0.28% due to the dual-mode resonance design of the sensor. The measured sensitivity of the proposed dual-mode microwave sensor at first and second resonance is as high as 7.4% and 9.9%, respectively. The proposed sensor is expected to be a cost-effective, more sensitive and accurate solution for dielectric characterization of edible oil and its quality assessment.