Microneedle array module and method of fabricating the same

• US 20020155737A1
• Filed: 06/05/2002
• Published: 10/24/2002
• Est. Priority Date: 08/21/2000
• Status: Active Grant

• Current Assignee: Cleveland Clinic Foundation
• Original Assignee: Cleveland Clinic Foundation
• Inventors: Fleischman, Aaron J., Roy, Shuvo
• Granted Patent: US 6,790,372 B2
• Time in Patent Office: Days
• US Class Current: 439/66
• CPC Class Codes: A61M 2037/003 having a lumen
• CPC Class Codes: A61M 2037/0038 having a channel at the side surface
• CPC Class Codes: A61M 2037/0053 Methods for producing microneedles
• CPC Class Codes: A61M 37/0015 by using microneedles
• CPC Class Codes: B81B 2201/055 Microneedles
• CPC Class Codes: B81C 1/00111 Tips, pillars, i.e. raised structures microneedles A61M37/0015

Abstract

A microneedle array module is disclosed comprising a multiplicity of microneedles affixed to and protruding outwardly from a front surface of a substrate to form the array, each microneedle of the array having a hollow section which extends through its center to an opening in the tip thereof. The substrate includes an array of holes which align with the hollow sections of the microneedles and extend through the substrate to a back surface thereof, whereby a liquid applied to the back surface of the substrate may be forced through the holes in the substrate and out through the tips of the microneedle array thereof. In one embodiment, the substrate includes a reservoir well in the back surface thereof. The well extends over the array of holes in the back surface and may be covered by a layer of material which is affixed to the back surface peripheral the well, the layer including an interconnecting passageway to the well.

A method of fabricating the microneedle array module is also disclosed comprising the steps of: providing etch resistant mask layers to one and another opposite surfaces of a substrate to predetermined thicknesses; patterning the etch resistant mask layer of the one surface for outer dimensions of the microneedles of the array; patterning the etch resistant mask layer of the other surface for inner dimensions of the microneedles of the array; etching unmasked portions of the substrate from one and the other surfaces to first and second predetermined depths, respectively; and removing the mask layers from the one and the other surfaces. One embodiment of the method includes the steps of: providing an etch resistant mask layer to the other surface of the substrate to a predetermined thickness; patterning the etch resistant mask layer of the other surface to define a reservoir region in the substrate; and etching away the unmasked reservoir region of the substrate to form a reservoir well in the other surface of the substrate. A layer of material may be provided to the other surface to enclose the reservoir well and a passageway is provided through the layer to the well region.

Claims

1. A microneedle array module comprising:

a substrate having front and back surfaces;

a multiplicity of microneedles affixed to and protruding outwardly from said front surface to form said array, each microneedle of said array having a hollow section which extends through its center to an opening in the tip thereof;

said substrate including an array of holes which align with the hollow sections of the microneedles and extend through the substrate to the back surface thereof, whereby a liquid applied to the back surface of said substrate may be forced through said holes in said substrate and out through the tips of the microneedle array thereof.

2. The module of claim 1 wherein the microneedles are cylindrical in shape in the direction of protrusion.

3. The module of claim 1 wherein the microneedles are conical in shape in the direction of protrusion.

4. The module of claim 1 wherein the dimensions of the microneedles protruding from the front surface are substantially the same.

5. The module of claim 1 wherein the dimensions of the microneedles protruding from the front surface are greater in dimension than a thickness of the substrate.

6. The module of claim 1 wherein the protruding dimensions of the microneedles are in the range of 50 to 2000 micrometers.

7. The module of claim 1 wherein the array of microneedles is fabricated from the substrate and forms an integral part thereof.

8. The module of claim 1 wherein the substrate includes a reservoir well in the back surface thereof.

9. The module of claim 8 wherein the well extends over the array of holes in the back surface.

10. The module of claim 8 including a layer of material covering the well and affixed to the back surface peripheral the well, said layer including an interconnecting passageway to the well.

11. The module of claim 10 wherein the layer of material comprises at least one material selected from the group consisting of a form of SiO₂, silicon, ceramic, and plastic.

12. The module of claim 1 wherein the substrate comprises silicon.

13. The module of claim 1 wherein the substrate comprises a form of SiO₂.

15. The method of claim 14 wherein the step of providing includes oxidizing the surfaces of the substrate to predetermined thicknesses.

16. The method of claim 15 wherein the step of oxidizing includes the step of thermally oxidizing the surfaces.

17. The method of claim 15 wherein the step of oxidizing includes chemically depositing an oxide on the surfaces.

18. The method of claim 14 wherein the step of providing includes the step of providing a mask layer of silicon nitride to the surfaces of the substrate.

19. The method of claim 14 wherein the step of providing includes the step of providing a mask layer of photoresist to the surfaces of the substrate.

20. The method of claim 14 wherein the unmasked portions of the substrate are etched anisotropically.

21. The method of claim 20 wherein the unmasked portions of the substrate are anisotropically etched using a deep reactive ion beam etching (RIE) process.

22. The method of claim 21 wherein the deep RIE process uses a SF₆ based ion beam.

23. The method of claim 14 wherein each step of patterning includes the steps of patterning the etch resistant mask layer using a photolithography process.

24. The method of claim 14 wherein the mask layers are removed away using a buffered hydrofluoric acid.

25. The method of claim 14 wherein the mask layers are removed away using a reactive ion etching (RIE) process.

26. The method of claim 25 wherein the mask layers are removed away using a fluorocarbon-based RIE.

27. The method of claim 14 wherein the second predetermined etching depths are greater than the first predetermined etching depths.

28. The method of claim 27 wherein the second etching depths leaving only thin layers of substrate at the one surface relative to the thickness of the substrate;

and wherein, the thin layers of unetched substrate portions are etched from the one surface to provide openings for microneedle tips of the array.

29. The method of claim 27 wherein the second etching depths creating openings in the one surface for the microneedle tips of the array.

30. The method of claim 14 including the steps of:

providing an etch resistant mask layer to the other surface of the substrate to a predetermined thickness;

patterning the etch resistant mask layer of the other surface to define a reservoir region in the substrate; and

etching away the unmasked reservoir region of the substrate to form a reservoir well in the other surface of the substrate.

31. The method of claim 30 including the steps of:

providing a layer of material to the other surface to enclose the reservoir well; and

providing a passageway through said layer to the well region.

32. The method of claim 31 including the reservoir well is enclosed by bonding a layer of material to the other surface.

33. The method of claim 32 wherein the material of the layer bonded to the other surface is selected from the group consisting of a form of SiO₂, silicon, ceramic, and plastic.

14. A method of fabricating a microneedle array module comprising the steps of:

providing etch resistant mask layers to one and another opposite surfaces of a substrate to predetermined thicknesses;

patterning the etch resistant mask layer of the one surface for outer dimensions of the microneedles of said array;

patterning the etch resistant mask layer of the other surface for inner dimensions of the microneedles of said array;

etching unmasked portions of said substrate from one and the other surfaces to first and second predetermined depths, respectively; and

removing the mask layers from the one and the other surfaces.