Microwave measurements combined with scanning probe microscopy is a novel tool to explore high-localized mechanical and electrical properties of biological species. Complex permittivities and permeabilities are detected through slight variations of an incident microwave signal. Here we report the high-frequency dependence of the electromagnetic dynamic characteristics in human monocytic leukemia cells (THP1) through local measurements by scanning microwave microscopy (SMM). The amplitude and phase images were shown to depend on the applied resonance frequency. While the amplitude yields information about the resistivity determined by the water and the ionic strength, the phase information reflects the dielectric losses arising from the fluid density.
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