Gas chromatography system and detector and method

• US 4,471,647 A
• Filed: 03/22/1982
• Issued: 09/18/1984
• Est. Priority Date: 04/18/1980
• Status: Expired due to Term

• Current Assignee: Board of Trustees of the Leland Stanford Junior University (Stanford University)
• Original Assignee: Board of Trustees of the Leland Stanford Junior University (Stanford University)
• Inventors: Jerman, John H., Terry, Stephen C.
• Primary Examiner(s): Kreitman, Stephen A.
• Application Number:
  US06/360,414
• Time in Patent Office: 911 Days
• Field of Search: 73/23.1, 73/23, 73/27 R, 73/204, 374/35, 374/135, 338/22 R, 338/25, 338/34, 338/22 SD
• US Class Current: 73/23.4
• CPC Class Codes: G01N 30/6095 Micromachined or nanomachined, e.g. micro- or nanosize
• CPC Class Codes: G01N 30/66 Thermal conductivity detectors
• CPC Class Codes: G01N 30/88 Integrated analysis systems specially adapted therefor, not covered by a single one of the groups G01N30/04 - G01N30/86

Abstract

There is described a gas chromatographic assembly formed on a semiconductor wafer by etching techniques. There is also described an improved thermal detector for use therewith.

Claims

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.

2. A detector for use in connection with gas chromatographic apparatus comprising:

an elongated metal film resistor, a membrane for supporting said metal film resistor said membrane having a plurality of holes permitting gas to flow on both sides of said membrane and means for supporting said membrane and film resistor.

3. Apparatus for use in temperature measurement comprising:

a metal film resistor, a membrane for supporting said film resistor said membrane having a plurality of apertures, means for supporting said membrane and film resistor, and means for heating said film resistor.

4. A chromatography assembly comprising:

a substrate body having at least one conduit therein for carrying a fluid;

a thermal conductivity detector assembly, attached to said body, at one end of said one conduit;

said detector assembly for measuring a certain property of the fluid flowing in said conduit past said detector assembly; and

said assembly comprising at least one elongated metal film resistor, a membrane having a plurality of aperatures for supporting said membrane and film resistor, and means for supporting said membrane and film resistor such that said membrane is spaced from said body and said fluid is carried past both sides of said membrane, whereby said metal film is substantially thermally insulated by said fluid.

5. The assembly of claim 4 wherein said membrane supports a plurality of film resistors.

6. The assembly of claim 5 wherein one of said film resistors is for heating and another of said film resistors is for detecting the property of said fluid.