Quantitative permittivity measurements of nanoliter fluid volumes from 50 MHz to 40 GHz with microfluidic channels

This paper describes the development of coplanar waveguide measurement structures integrated with microfluidic channels in order to rapidly determine the broadband dielectric properties of nanoliter volumes of fluids, fluid mixtures, and colloids over the range of frequencies from 50 MHz to 40 GHz. A number of different integrated microfluidic-microelectronic structures are employed in order to quantitatively determine the complex permittivity function over this wide range of frequencies. Transmission line network models are developed that use experimentally derived parameters to de-embed the response of the fluid-loaded devices, and finite-element models relate the fluid complex permittivity to the transmission line circuit parameters.