Novel Microwave Fluid Sensor for Complex Dielectric Parameter Measurement of Ethanol–Water Solution

In this article, a 2.45-GHz band microwave sensor (MWS) design is introduced to be utilized for the dielectric constant determination of ethanol–water solutions. The introduced MWS is composed of two symmetrically positioned, directly coupled interconnected split-ring resonators with a circular ring-shaped detection area in the middle region, into which a small amount of ethanol–water solution is dropped. The fabricated prototype of the MWS has a total component size of $12\times30$ mm on the Rogers RO4003 substrate. The sensor measurement performance is numerically evaluated and experimentally validated in good agreement. The introduced MWS has the structural design novelty of possessing the main detection region in a form of a circular hollow where a disposable 3-D printed fluid cup can be accommodated for multiple uses. The introduced MWS has the technical feasibility to be used as an ingredient identification device for chemical solutions to figure out complex dielectric parameters of ethanol–water specimens with small, low-cost, reusable, and easy-to-fabricate features, as well as the determination of volume percentage concentration of ethanol content.