This paper presents a new concept based on the gap waveguide topology realized in LTCC (Low Temperature Co-fired Ceramic) technique for microfluidic applications. The proposed structure consists on a gap waveguide structure acting as a resonator. The interaction between the electric field and the liquid under test translates into predictable relationship between the characteristics of the resonator (resonant frequency, Q factor) and the complex permittivity of the fluid. This work provides new applications on the gap waveguide concept relative to the detection and the exploration of microfluidic applications. Moreover, an improvement in the detection of the sensibility compared to other topologies like Substrate Integrated Cavity has been done.