Patent ID: 7301642

Claim:
An assay apparatus for assay in utilizing attenuated total reflection by use of a sensor unit including a transparent dielectric medium, and a thin film, having a first surface and a sensing surface reverse thereto, said first surface being connected with said dielectric medium to constitute a thin film/dielectric interface, wherein a flow channel is used, has an entrance end opening and an exit end opening, and causes sample fluid introduced through said entrance end opening to flow on said sensing surface, there being an optical assay unit for traveling of illuminating light to said interface in a form satisfying a total reflection condition, and for assaying reaction of said sample fluid on said sensing surface by detecting attenuation of said illuminated light reflected by said interface, said assay apparatus comprising: a fluid dispenser for introducing said sample fluid to said entrance end opening; a fluid collecting vessel for storing said sample fluid used and exited from said exit end opening; a drain conduit, disposed to extend from said exit end opening toward said fluid collecting vessel, for passage of said used sample fluid; and a suction device for draining said used sample fluid into said fluid collecting vessel by suction thereof through said drain conduit.