Due to the need to make measurements quickly, easily, with high accuracy and that above all do not affect the test material, RF devices have been used since they have easy manufacturing, simple electronics associated with their design, use quantities very small to make the measurements and a quick response of the sensor. In this work we propose the design of RF sensors for the detection of changes in the concentration of liquid substances from the change of a physical property of the materials such as permittivity, this case in particular will be the permittivity of the test substance which in turn allows the electrical characterization of the material so that it went through a design stage by means of simulation software and later the designs were made in their respective substrates by means of a CNC, later the experimental tests were done to obtain the data that then they would be contrasted with their response in simulation to corroborate the behavior of the designs. The experimental spectra of some alcohols were obtained and validated with the curves of the simulations where the correlation between the simulated and experimental data in both sensors could be observed, besides it was proved that one of the designs can work for two bands simultaneously without make some kind of modification in its geometry, all this in a sensor of compact size and with simple electronics associated with its with its design