A 90 GHz liquid sensing substrate integrated cavity resonator in LTCC for microfluidic sensing applications

This paper presents a reflection-type 90 GHz substrate integrated cavity resonator sensor realized in LTCC technology for lab-on-chip microfluidic applications. A linear relationship between the resonance frequency of the sensor and the permittivity of the material under test was observed from measurements on low-loss materials. Calibration curves are also obtained for water-isopropanol mixtures which show monotonic behaviours with respect to the isopropanol concentrations. Measurements of the sensor thus demonstrate that it is promising for lab-on-chip microfluidic sensing applications.