Integrated monolithic microfabricated dispensing nozzle and liquid chromatography-electrospray system and method

• US 6,768,107 B2
• Filed: 04/30/2003
• Issued: 07/27/2004
• Est. Priority Date: 03/02/1999
• Status: Expired due to Term

• Current Assignee: Rheonix, Inc.
• Original Assignee: Advion BioSciences Incorporated, Kionix Incorporated (ROHM Co., Ltd.)
• Inventors: Schultz, Gary A., Corso, Thomas N.
• Primary Examiner(s): Wells, Nikita
• Application Number:
  US10/426,455
• Publication Number:
  US 20040016878A1
• Time in Patent Office: 454 Days
• Field of Search: 250/288, 250/281, 250/282, 250/423.R, 210/198.2, 210/748, 430/313, 430/320
• US Class Current: 250/288
• 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

Abstract

A droplet/electrospray device and a liquid chromatography-electrospray system are disclosed. The droplet/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 droplets or an electrospray. A plurality of these electrospray devices can be used in the form of an array of miniaturized nozzles. The liquid chromatography-electrospray 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 is bonded to the separation substrate to enclose the reservoir and the separation channel adjacent the cover substrate. The exit orifice of the liquid chromatography device is homogeneously interfaced with the entrance orifice of the electrospray device to form an integrated single system. Procedures for fabrication of the electrospray devices of the present invention are also disclosed.

Claims

1. A method of producing an electrospray device comprising:

providing a substrate having opposed first and second surfaces, each coated with a photoresist;

exposing the photoresist on the first surface to an image to form a pattern in the form of a spot on the first surface;

removing the photoresist on the first surface where the pattern is in the form of a hole in the photoresist;

removing material from the substrate coincident with the hole in the photoresist on the first surface to form a channel extending through the photoresist on the first surface and through the substrate up to the photoresist on the second surface;

exposing the photoresist on the second surface to an image to form an annular pattern circumscribing an extension of the channel through the photoresist on the second surface;

removing the photoresist on the second surface where the annular pattern is;

removing material front the substrate coincident with where the pattern in the photoresist on the second surface has been removed to form an annular recess extending partially into the the substrate; and

removing all coatings from the first and second surface of the substrate to form the electrospray device.

2. A method according to claim 1, wherein the substrate is silicon and layers of silicon dioxide are present between the coatings of photoresist and the substrate, said method further comprising:

removing the silicon dioxide from the first surface after said removing the photoresist on the first surface and

removing the silicon dioxide from the second surface after said removing the photoresist on the second surface.

3. A method of producing an electrospray device comprising:

providing a substrate having opposed lust and second surfaces, each coated with a photoresist;

exposing the photoresist on the first surface to an image to form a pattern in the form of at least 3 substantially aligned spots on the first surface;

removing the photoresist on the first surface where the pattern is in the form of 3 holes in the photoresist corresponding to where the spots in the photoresist were;

removing material from the substrate coincident with where the pattern in the photoresist on the first surface has been removed to faint a central channel aligned with and between two outer channels, said channels extending through the photoresist on the first surface and into the substrate, wherein the central channel has a diameter which is less than that of the outer channels such that the central channel extends farther from the second surface at the substrate than the outer channels which extend up to the photoresist on the the second surface;

exposing the photoresist on the second surface to an image which forms an annular pattern circumscribing a spot, wherein the spot is coincident with an extension of the central channel through the photoresist on the second surface and a portion of the substrate;

removing the photoresist on the second surface where the annular pattern circumscribing the spot is;

removing material from the substrate coincident with where the pattern in the photoresist on the second surface has been removed to form an annular recess extending partially into the substrate which circumscribes the central channel which extends through the substrate and the photoresist on the first and second surfaces;

removing alt coatings from the first and second surfaces of the substrate; and

coating all surfaces of the substrate with an insulating material to form the electrospray device.

4. A method according to claim 3, wherein the substrate is silicon and layers or silicon dioxide are present between she coatings of photoresist and the substrate, said method further comprising:

removing the silicon dioxide from the first surface after said removing the photoresist on the first surface and

removing the silicon dioxide from the second surface after said removing the photoresist on the second surface.

5. A method according to claim 3, wherein the insulating material is selected from the group consisting of silicone dioxide, silicon nitride, and combinations thereof.

6. A method of forming a liquid separation device comprising:

providing a substrate having opposed first and second surfaces, each coated with a photoresist;

exposing the photoresist on the first surface to an image to form a pattern in the form of a plurality of spots on the first surface;

removing the photoresist on the first surface where the pattern is in she form of a plurality of holes in the photoresist corresponding to where the spots in due photoresist were;

removing material front the substrate coincident with where the pattern in the photoresist on the first surface has been removed to form a large reservoir proximate a first end of the substrate and a plurality of smaller holes closer to a second opposite end or the substrate than the reservoir, said reservoir and holes extending through the photoresist on the first surface and partially into the substrate;

filling the smaller holes and surfaces of the reservoir with a coating;

applying a further photoresist layer over the coating on the surfaces of the reservoir, the filled holes, and the photoresist on the first surface;

exposing the further photoresist to an image to form a pattern in the form of spots, with one spot coincident with what was part of the reservoir and the other spot being closer to the second end of the substrate than the filled holes;

removing the further photoresist where the pattern is to form holes corresponding to where the spots in the photoresist were;

removing material from the substrate coincident with where the pattern in the further photoresist has been removed to form a pair of channels, with a first channel extending through what was the reservoir up to the photoresist on the second surface and a second channel extending through the substrate up to the photoresist on the second surface at a location closer to the second end of the substrate than the filled holes; and

removing all coatings from the first and second surfaces of the substrate; and

coating all surfaces of the substrate with an insulating material to form the liquid separation device.

7. A method according to claim 6, wherein, between said removing material from the substrate coincident with where the pattern in the further photoresist has been removed and said removing all coatings, said method further comprises:

exposing the photoresist on the second surface to an image which forms an annular pattern circumscribing on extension of the first channel through the photoresist on the second surface;

removing the photoresist on the second surface where the annular pattern is; and

removing material from the substrate coincident with where the pattern in the photoresist on the second surface has been removed to form an annular recess extending partially into the substrate which circumscribes the first channel which extends through the substrate and the photoresist on the first and second surfaces.

8. A method according to claim 7, wherein the substrate is silicon and layers of silicon dioxide are present between the coatings of photoresist and the substrate, said method further comprising:

removing the silicon dioxide from the first surface after said removing the photoresist on the first surface and

removing the silicon dioxide from the second surface after said removing the photoresist on the second surface.

9. A method according to claim 6, wherein the insulating material as selected from the group consisting of silicone dioxide, silicon nitride, and combinations thereof.

10. A method according to claim 6, wherein said removing material from the substrate further define posts in the substrate.

11. A method according to claim 10, wherein posts are silicon, said method further comprising:

oxidizing the silicon posts to produce silicon dioxide posts.