A microfluidic device for high frequency characterization of fluids under high dc electric fields

The design and fabrication of a broadband microwave microfluidic device are presented together with our preliminary measurement results on water dielectric saturation effects. Heavily-doped silicon is used to form microstrip lines and 250 nm deep planar microfluidic channels. The atomically smooth surfaces enable ~ 0.9 MV/cm dc electric fields across the channel without breakdown issues. High frequency scattering parameter measurements are conducted under different uniform dc electric fields. When the applied dc field is increased to ~ 0.9 MV/cm, extracted water permittivity, ε\´ and ε", are reduced by as much as 21 % and 11 %, respectively. Future work includes achieving reliable contacts and on-chip de-embedding procedures.