This paper presents a sensing device, useful for the measurement of small concentrations of solute content in liquids, based on a splitter/combiner microstrip structure loaded with a pair of split ring resonators (SRRs) in a symmetric configuration. The operation principle is similar to differential sensing, where one of the SRRs is put in contact with the reference liquid (the solvent), whereas the solution (or liquid under test-LUT) is forced to flow on top of the other SRR, the sensing element. To this end, fluidic channels are added on top of the SRRs, which are covered by a dry film in order to avoid substrate absorption. The asymmetry, caused by the presence of solute content in the LUT, modifies the response of the structure with regard to the one with identical liquids (pure solvent) in both channels, and the solute concentration can be inferred. In this work, it is demonstrated that glucose and sodium concentrations as small as 1 g/L and 0.5 g/L, respectively, in DI water can be measured.