Gas chromatography system and detector and method

Claim 1

A gas chromatography assembly comprising: a wafer of semiconductor material including an elongated etched capillary groove; an etched carrier gas inlet groove having one end connected to one end of said capillary groove; a first feedthrough extending through the wafer and connected to the connected ends of said capillary and carrier gas grooves; a carrier gas inlet feedthrough connected to the other end of said inlet groove; an etched sample gas inlet groove; second and third feedthroughs connected to the ends of said sample gas groove with said third feedthrough closely spaced to said first feedthrough; an etched exchaust groove; fourth and fifth feedthroughs connected to the ends of said exhaust groove with said fourth feedthrough closely spaced to said first feedthrough; valve means cooperating with said first, third and fourth feedthroughs serving to selectively connect the sample gas input groove and the exhaust groove to the first feedthrough; a sixth feedthrough at the other end of said capillary groove; a vent groove; seventh and eighth feedthroughs connected to the ends of said vent groove with the seventh feedthrough spaced with respect to the sixth feedthrough; a plate cooperating with the grooved surface of said wafer to define carrier gas input, sample gas input and vent conduits and a capillary column; a thermal conductivity detector assembly comprising a thin metal film resistance means including a thin supporting membrane supported on a semiconductor support which includes a cavity behind the membrane mounted opposite and spaced from said wafer between said seventh and eight feedthroughs said supporting including openings which permit gas to flow on both sides of the membrane and a thin elongated metal film carried by said membrane; and means for directing the gas flowing from said capillary column past the detector to flow over both sides of the membrane to the vent groove.