Abstarct: Microwave sensors baxsed on planar electric resonators are of significant importance due to their high sensitivity to the surrounding environment, particularly the dielectric constant. These sensors are highly effective in characterizing the dielectric properties of liquid and solid materials, as well as in measuring the compositional properties of substances. This research explores the key advantages and limitations of planar microwave resonator sensors and introduces several studies, primarily focusing on sensors baxsed on microfluidics and capillary tubes. The proposed sensors have broad applications in the detection of industrial and biological samples. In this thesis, a microwave sensor was designed, simulated, and fabricated using microstrip transmission lines and a substrate made of Rogers RO4003C (lossy) with a thickness of 800 micrometers, a dielectric constant of 3.55, and a loss tangent of 0.0027, all within the CST software environment. This sensor exhibits notable precision and sensitivity, with the capability to measure and resonate across multiple frequency ranges. Key features of this sensor include its compact and portable design, the small sample volume required for measurement, low fabrication cost, and high sensitivity. The sensor was tested with materials such as water, ethanol, and blood, and the sensitivity of the proposed sensor was determined to be 15.4 MHz.m.F-1.