Microwave ring resonator-based non-contact interface sensor for oil sands applications

• A planar microwave resonator sensor in noncontact method for oil sand applications.
• A sensor with variable quality factor and resolution is reported.
• An analytical study on microwave sensor for different materials and various interfaces in between liquids is presented.
• The sensor is inexpensive, simple and has ability to operate in harsh environments.

This paper presents the design, fabrication, and characterization of a non-contact microwave resonator sensor for liquid–liquid interface detection. The core of this sensor is a microwave planar ring resonator tuned at 5.25 GHz with a Q factor of 180. The geometry and materials of the designed sensor were optimized for higher sensitivity by finite element modeling and simulations. Here we demonstrate the detection of different liquid–liquid interfaces such as water–olive oil, water–olive oil–ethanol, and rag layer samples using microwave resonator method. In the proposed sensor, the resonance frequency demonstrated a maximum variation of 5.7% for water to rag layer interface. To increase the accuracy of the sensor in the interface detection, quality factor is also measured and demonstrated a maximum variation of 85% depending on the materials. The proposed sensor provides a non-contact real time, cost-effective, robust method for interface detection, which has potential applications in the oil sands industry.