Surface-micromachined microfluidic devices

• US 6,797,187 B1
• Filed: 01/24/2003
• Issued: 09/28/2004
• Est. Priority Date: 11/13/2000
• Status: Active Grant

• Current Assignee: National Technology & Engineering Solutions Of Sandia LLC (Honeywell International Inc.)
• Original Assignee: Sandia Corporation (Martin Marietta Corporation)
• Inventors: Paul, Phillip H., Montague, Stephen, Okandan, Murat, Nichols, Christopher A., Galambos, Paul C., Smith, James H., Jakubczak, Jerome F. II, Krygowski, Thomas W., Allen, James J.
• Primary Examiner(s): OLSEN, ALLAN W
• Application Number:
  US10/351,135
• Time in Patent Office: 613 Days
• Field of Search: 216/2, 216/16, 216/27, 216/41, 216/80, 216/97, 438/21, 438/49-54, 219/630
• US Class Current: 216/2
• CPC Class Codes: B01J 19/0093 Microreactors, e.g. miniaturised or microfabricated reactors laboratory containers with capillary fluid transport in microfabricated channels or chambers B01L3/5027
• CPC Class Codes: B01J 2219/00783 Laminate assemblies, i.e. the reactor comprising a stack of plates
• CPC Class Codes: B01J 2219/00828 Silicon wafers or plates
• CPC Class Codes: B01J 2219/00853 Employing electrode arrangements
• CPC Class Codes: B01L 2200/12 Specific details about manufacturing devices
• CPC Class Codes: B01L 2400/0418 electro-osmotic flow [EOF]
• CPC Class Codes: B01L 3/502707 characterised by the manufacture of the container or its components by shaping or joining plastic parts B29C59/00, B29C65/00; by laminating B32B37/00; manufacture of microstructural devices in general B81C
• CPC Class Codes: G01N 2030/0035 electrical field
• CPC Class Codes: G01N 2030/285 electrically driven carrier
• CPC Class Codes: G01N 2030/326 pumps
• CPC Class Codes: G01N 27/44773 Multi-stage electrophoresis, e.g. two-dimensional electrophoresis
• CPC Class Codes: G01N 27/44791 Microapparatus sample containers with integrated microfluidic structures B01L3/5027
• CPC Class Codes: G01N 30/0005 Field flow fractionation
• CPC Class Codes: G01N 30/02 Column chromatography
• CPC Class Codes: G01N 30/6069 with compartments or bed substructure
• CPC Class Codes: G01N 30/6095 Micromachined or nanomachined, e.g. micro- or nanosize

Abstract

Microfluidic devices are disclosed which can be manufactured using surface-micromachining. These devices utilize an electroosmotic force or an electromagnetic field to generate a flow of a fluid in a microchannel that is lined, at least in part, with silicon nitride. Additional electrodes can be provided within or about the microchannel for separating particular constituents in the fluid during the flow based on charge state or magnetic moment. The fluid can also be pressurized in the channel. The present invention has many different applications including electrokinetic pumping, chemical and biochemical analysis (e.g. based on electrophoresis or chromatography), conducting chemical reactions on a microscopic scale, and forming hydraulic actuators.

Claims

1. A method for forming a fluid-flow channel on a substrate, comprising steps for:

(a) depositing a first layer of silicon nitride on the substrate;

(b) depositing at least one layer of a sacrificial material over the first layer of silicon nitride, and patterning the sacrificial material to define a nonuniform shape for the channel, with the nonuniform shape including a constricted portion of the channel which has a height that is smaller than the height of the remainder of the channel;

(c) depositing a second layer of silicon nitride over the patterned sacrificial material, with the second layer of silicon nitride conforming to the nonuniform shape of the channel;

(d) forming a plurality of vertically-disposed electrical conductors spaced along the length of the constricted portion; and

(e) removing the sacrificial material from the channel.

2. The method of claim 1 wherein the sacrificial material comprises silicon dioxide or a silicate glass.

3. The method of claim 1 further including a step for forming a plurality of horizontally-disposed electrical conductors, with each horizontally-disposed electrical conductor being electrically connected to a pair of the vertically-disposed electrical conductors, thereby forming a coil.

4. The method of claim 1 further including a step for forming electrical wiring below the first layer of silicon nitride, with the electrical wiring being electrically connected to the plurality of vertically-disposed electrical conductors for activation thereof.

5. The method of claim 1 wherein the step for patterning the sacrificial material comprises steps for forming a patterned hard mask over the sacrificial material and etching the sacrificial material.

6. The method of claim 5 wherein the step for patterning the sacrificial material produces a flow region of the channel having tapered sidewalls.