Integrated monolithic microfabricated electrospray and liquid chromatography system and method

• US 6,394,942 B2
• Filed: 12/21/2000
• Issued: 05/28/2002
• Est. Priority Date: 09/17/1998
• Status: Expired due to Term

• Current Assignee: Rheonix, Inc.
• Original Assignee: Kionix Incorporated (ROHM Co., Ltd.)
• Inventors: Davis, Timothy J., Moon, James E., Galvin, Gregory J.
• Primary Examiner(s): Nelms, David
• Assistant Examiner(s): Le, Thao P
• Application Number:
  US09/746,419
• Publication Number:
  US 20010016424A1
• Time in Patent Office: 523 Days
• Field of Search: 438/712,713,719,689 204/299,180.1 210/198.2
• US Class Current: 438/712
• CPC Class Codes: G01N 30/6095 Micromachined or nanomachined, e.g. micro- or nanosize
• CPC Class Codes: G01N 30/7266 by electric field, e.g. electrospray
• CPC Class Codes: H01J 49/0018 Microminiaturised spectrometers, e.g. chip-integrated devices, Micro-Electro-Mechanical Systems [MEMS]
• CPC Class Codes: H01J 49/167 Capillaries and nozzles specially adapted therefor; electrostatic spraying per se B05B5/00
• CPC Class Codes: Y10T 29/49002 Electrical device making
• CPC Class Codes: Y10T 436/25375 Liberation or purification of sample or separation of material from a sample [e.g., filtering, centrifuging, etc.]
• CPC Class Codes: Y10T 436/255 including use of a solid sorbent, semipermeable membrane, or liquid extraction

Abstract

An electrospray device, a liquid chromatography device and an electrosprayliquid chromatography system are disclosed. The electrospray device comprises a substrate defining a channel between an entrance orifice on an injection surface and an exit orifice on an ejection surface, a nozzle defined by a portion recessed from the ejection surface surrounding the exit orifice, and an electrode for application of an electric potential to the substrate to optimize and generate an electrospray; and, optionally, additional electrode(s) to further modify the electrospray. The liquid chromatography device comprises a separation substrate defining an introduction channel between an entrance orifice and a reservoir and a separation channel between the reservoir and an exit orifice, the separation channel being populated with separation posts perpendicular to the fluid flow; a cover substrate bonded to the separation substrate to enclose the reservoir and the separation channel adjacent the cover substrate; and, optionally, electrode(s) for application of a electric potential to the fluid. The exit orifice of the liquid chromatography device may be homogeneously interfaced with the entrance orifice of the electrospray device to form an integrated single system. An array of multiple systems may-be fabricated in a single monolithic chip for rapid sequential fluid processing and generation of electrospray for subsequent analysis, such as by positioning the exit orifices of the electrospray devices near the sampling orifice of a mass spectrometer.

Claims

1. A process for fabricating a chemical separation device, comprising:

providing a silicon substrate; and

forming, by reactive-ion etching, a channel recessed into a major surface of said substrate, said channel having a plurality of posts, wherein said posts extend from and perpendicular to a bottom of said channel.

2. The process of claim 1, further comprising forming a layer of silicon oxide, during the step of forming said channel and said plurality of posts, to act as a mask during said reactive-ion etching.

3. The process of claim 1, further comprising forming an insulating layer over a surface of said channel and a surface of said plurality of posts.

4. The process of claim 3, wherein said insulating layer is silicon oxide, and said step of forming said silicon oxide includes one of thermally oxidizing silicon and depositing said silicon oxide using a deposition technique.

5. The process of claim 1, further comprising forming at least one electrode to apply electrical potential to at least one location in said channel such that said at least one electrode is on an exterior exposed surface of said channel.

6. The process of claim 1, further comprising forming controlling circuitry for said chemical separation device, said circuitry being integrated on said substrate.

7. A process for fabricating a chemical separation system, comprising:

providing a first substrate having a first surface;

forming, at least in part by reactive-ion etching, a channel extending into said substrate from said first surface;

forming, at least in part by reactive-ion etching, a plurality of posts from said substrate, said posts being contained within said channel, perpendicular to a bottom of said channel and extending from said bottom of said channel to said first surface;

providing a second substrate; and

attaching said second substrate to said first surface of said first substrate to cover at least a portion of said channel. said substrate, said posts being contained within said channel, perpendicular to a bottom of said channel and extending from said bottom of said channel to said first surface;

providing a second substrate; and

attaching said second substrate to said first surface of said first substrate to cover at least a portion of said channel.

8. The process of claim 7, wherein at least one of said first and second substrates are silicon.

9. The process of claim 7, further comprising attaching a stationary phase compound to said plurality of posts.

10. The process of claim 7, wherein the step of attaching said second substrate to said first substrate is accomplished by anodic bonding.

11. The process of claim 7, further comprising forming controlling circuitry for said chemical separation system, said circuitry being integrated on at least one of said first and second substrates.