US Patent 7633301 Track position sensor and method

A low impedance sensor includes thin conductive electrodes on a dielectric substrate and detects proximity of a target metal object or structure moving along defined path such as a track. The sensor includes a first conductive electrode pad having a closed, continuous geometric form and a second conductive electrode surrounding the first electrode and spaced from the first electrode by a channel of non-conductive dielectric. The first and second electrodes are optionally disposed on the same surface of the substrate. An integrated control circuit is located on the substrate proximate the first and second electrodes, and is electrically coupled to the first and second electrodes.