Dielectric spectroscopy for bioanalysis: From 40 Hz to 26.5 GHz in a microfabricated wave guide

We report developing coplanar waveguide devices which can perform dielectri c spectroscopy on biological samples within a microfluidic channel or well. Since coupling to the fluid sample is capacitive, no surface functionaliza tion or chemical sample preparation are required. Data on cell suspensions and solutions of proteins and nucleic acids spanning the frequency range fr om 40 Hz to 26.5 GHz are presented. Low-frequency data are well explained u sing a simple dispersion model. At microwave frequencies, the devices yield reproducible and distinguishable spectral responses for hemoglobin solutio n and live E. coli. (C) 2001 American Institute of Physics.