This work proposes an advancement of microwave planar resonator sensor with high sensitivity for microfluidic dielectric characterization. The physical design was employed based on circular substrate integrated waveguide (CSIW) with an integration of defected microstrip structure (DMS). This approach can be applied to accelerate the dielectric detection, structure miniaturization and material differentiation. The presented sensor operates based on variations in the dielectric properties of solvents in the vicinity of a planar open‐ended microstrip resonator device. Further analysis in volume and concentration were performed to validate the reliability of the sensor. Validation and functionality of the sensor were investigated by experimental and results comparison. A mathematical model was developed to determine the dielectric constant and the loss tangent of the microfluidic samples. The average error detection has a lower percentage value of 0.11% by comparison to the commercial and ideal dielectric properties of the aqueous samples. The maximum relative error detection, ±0.37% implied better accuracy compared to the existing resonator sensors with more than 400 of the Q‐factor. The proposed CSIW‐DMS sensor was found to give higher accuracy and detection response; besides easier to fabricate, and compatible for integration with other electronic components in an RF sensor for variety of applications.

In this paper, a new design of microwave sensor with high Q-factor for liquid characterization is analyzed and investigated. The new microwave sensor is based on a gap waveguide cavity resonator (GWCR). The GWCR consists of upper plate, lower plate and array of pins on the lower plate. The liquid under test (LUT) is characterized by placing it inside the GWCR where the electric field concentrates using a quartz capillary that is passing through microfluidic channels. The results show that the proposed sensor has a high Q-factor of 4832. Moreover, the proposed sensor has the ability to characterize different types of liquids such as oils, ethanol, methanol and distilled water. The polynomial fitting method is used to extract the equation of the unknown permittivity of the LUT. The results show that the evaluated permittivity using the proposed sensor has a good agreement with the reference permittivity. Therefore, the proposed sensor is a good candidate for food and pharmaceutical applications.

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<span lang="EN-US">In this paper, a novel microwave sensor with high Q-factor for oil sensing is analyzed and investigated. The new design is based on a gap waveguide cavity resonator (GWCR). To characterize and evaluate the sample, the oil under tested (OUT) is injected into a Teflon tube, which is passing through the microfluidic channel that is located in the middle of the cavity where the electric field concentrates. The results show that the proposed sensor has a high Q-factor of 4832. Moreover, the proposed design has the ability to sense and detect different types of oils with a small variation of permittivities such as Fish oil, Coconut oil, Olive oil, Linseed oil and Castor oil. The permittivity equation is extracted using the polynomial fitting method to define unknown dielectric properties of the OUT. The results show that the evaluated permittivity using the proposed sensor has a good agreement with the ideal permittivity. Therefore, the proposed sensor is a good candidate for oil processing in food industries.</span>

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