Characterization of biological substances using a substrate integrated microwave near-field sensor

Measurements performed with a 3.1 GHz substrate integrated near-field sensor on aqueous solutions are reported. The samples include Chinese hamster ovary (CHO) cells in a culture medium as a representative and easily reproducible biological environment. The permittivity contrast between the cells and the surrounding medium is estimated based on perturbation theory. The resolution and sensitivity required for a device capable of single cell measurements at microwave frequencies are discussed based on these results.