A Review of Microwave Resonant Sensors for Liquid Samples Detection

Microwave sensors have been used for numerous applications and one of the most important is as material sensors due to their high sensitivity for detecting permittivity variations. According to the method of operation, they can be classified into resonant and broadband sensors. This article presents a brief review on the principal structures used as resonant sensors, with particular focus on liquid samples. Its main characteristics and applications are also discussed in the manuscript.