This paper deals with the concept of microliter sensing of human blood samples by waveguide dielectrometry at microwave frequency (39.5 GHz). The methods, research protocol, and basic results derived from the permittivity measurements are presented. Here we summarize the results of our 5-year research on developing a multidisciplinary approach to the characterization of erythrocytes dielectric response, in parallel with biochemical studies of their receptor-membrane activity, within the scope of a case–control study for in vitro diagnostics of acute and chronic neurological conditions.