A chromatographic assay device for use with immunoassays allows rapid and convenient assays of analytes of biological interest, and permits extractions to be carried out in situ, avoiding the use of separate extraction vessels. The device has a wide dynamic range and avoids interference from particulates...http://www.google.es/patents/US5869345?utm_source=gb-gplus-sharePatente US5869345 - Opposable-element assay device employing conductive barrier
