Transit time coplanar probe for biomolecular interactions at an aqueous-solid interface

The displacement of water from a solid-aqueous interface by a low-dielectric constant film that is a few nanometers thick can be detected as a change in the transit time of a baseband electrical pulse, of picosecond duration, propagating in a coplanar transmission line. The results of an electromagnetic analysis are experimentally verified by depositing polyelectrolyte monolayers on the probe surface and measuring changes in the pulse transit time of a short baseband electrical pulse.