Two planar resonant sensors for biomedical applications are compared with respect to their functionality when measuring high-loss materials. One sensor is a split-ring resonator. Liquid samples are placed at the gap where the conductor is shaped into tips. When sensing high-loss materials such as water this sensor type has a very low quality factor and therefore the evaluation of the resonance becomes inaccurate. To improve the quality factor, the second sensor uses a dielectric resonator as coupling element between the feed line and the split-ring resonator. Both sensors are tested on water and saline solutions. It is shown that the dielectric resonator drastically improves the quality factor of the sensing design and therefore enhances the accuracy of the sensor with respect to material characterization.