Silicon micro-machined projection with duct

• US 6,815,360 B1
• Filed: 02/08/2001
• Issued: 11/09/2004
• Est. Priority Date: 07/22/1998
• Status: Expired due to Term

• Current Assignee: Hanger Solutions, LLC (IP Investments Group LLC)
• Original Assignee: Qinetiq Limited (QinetiQ Group PLC)
• Inventors: Reeves, Christopher L., Canham, Leigh T, Cox, Timothy I
• Primary Examiner(s): Deo, Duy-Vu
• Application Number:
  US09/744,152
• Time in Patent Office: 1,370 Days
• Field of Search: 438/689, 438/706, 438/709, 438/719, 438/745, 438/753
• US Class Current: 438/706
• CPC Class Codes: A61B 5/14514 using means for aiding extraction of interstitial fluid, e.g. microneedles or suction
• CPC Class Codes: A61B 5/150022 for capillary blood or interstitial fluid
• CPC Class Codes: A61B 5/150282 for piercing elements, e.g. blade, lancet, canula, needle
• CPC Class Codes: A61B 5/150396 Specific tip design, e.g. for improved penetration characteristics
• CPC Class Codes: A61B 5/150969 Low-profile devices which resemble patches or plasters, e.g. also allowing collection of blood samples for testing
• CPC Class Codes: A61B 5/150984 Microneedles or microblades
• CPC Class Codes: B81B 2201/055 Microneedles
• CPC Class Codes: B81C 1/00087 Holes
• CPC Class Codes: B81C 1/00111 Tips, pillars, i.e. raised structures microneedles A61M37/0015

Abstract

A method of providing a microprojection (180) on the surface of a first material, the microprojection having a base portion adjacent the first material and a remote, or a tip portion, and a duct (182) at least in a region of the tip portion and the method comprising micro-machining the first material to provide the micro-projection duct. Various uses of the microprojection are also disclosed including light guides and cuvettes from micro-analytical systems, microneedles for transdermal fluid delivery or the like.

Claims

1. A method of providing a silicon micro-needle, the micro-needle having a base adjoining a silicon substrate, a tip remote from said base, and a duct passing from said base to said tip, the method comprising:

a. providing a duct in said silicon substrate; and

subsequently

b. selectively removing the substrate from around the duct to provide a micro-needle coincident with the duct.

2. A method according to claim 1 wherein a mask is lithographically provided on a substrate of the first material prior to the formation of the duct.

3. A method according to claim 2 wherein the mask is used to provide the duct which is fabricated by any one of the following techniques:

plasma enhanced etching, laser ablation, light assisted anodisation, ion beam milling, focused ion beam milling.

4. A method according to claim 1 wherein the micro-needle is bounded by planes of the first material which have a low etch rate.

5. A method according to claim 4 wherein an anisotropic etch is used to selectively remove the first material.

6. A method according to claim 1 wherein the first material is removed by any one of the following methods:

focused ion beam milling, etching combined with a domed resist mask.

7. A method according to claim 1 wherein the method is arranged to provide a micro-needle whose outer walls are inclined to a plane that is perpendicular to the substrate to which the micro-needles are adjacent.

8. A method according to claim 1 in which once the micro-needle has been created the method further includes linking the duct to a reservoir.

9. A method according to claim 8 in which a portion of the first material is removed from a side opposite a side of the first material where the micro-needle has been fabricated.

10. A method according to claim 8 in which the first material is attached to a second piece of material.

11. A method according to claim 10 in which the second piece of material has a channel which connects to the duct and links the duct to a reservoir.

12. A method according to claim 10 in which the first material has a channel which connects to the duct and links the duct to a reservoir.

13. A method according to claim 10 in which the two pieces of material are fabricated from same material.

14. A method according to claim 1 in which the micro-projection is fabricated substantially normal to the surface of the first material.

15. A method according to claim 1 wherein a surface region of the micro-needle is porosified after the needle has been fabricated.

16. A method according to claim 15 wherein the porosification is provided by one of the following techniques:

electrochemical anodisation, or immersing the structure is a stain etching solution.

17. A method of providing a silicon micro-needle, the micro-needle having a base adjoining a silicon substrate, a tip remote from said base, and a duct passing from said base to said tip, the method comprising:

a. selectively removing the silicon substrate to provide a micro-needle; and

subsequently

b. providing a duct coincident with the micro-needle.

18. A method according to claim 17 wherein the micro-needle is bounded by planes of the first material which have a low etch rate.

19. A method according to claim 18 wherein an anisotropic etch is used to selectively remove the first material.

20. A method according to claim 17 wherein said micro-needle is formed by any one of the following techniques:

focused ion beam milling, etching combined with a domed resist mask.

21. A method according to claim 17 wherein once the micro-needle has been formed a planar surface is provide covering the micro-needle.

22. A method according to claim 21 wherein the duct is provided by lithographic processes performed on the planar surface.

23. A method according to claim 22 wherein once the duct has been provided the planar surface is removed.

24. A method of providing a micro-needle on the surface of a first material, the micro-needle having a base adjoining the first material, a tip remote from said base, and a duct passing from said base to said tip, the method comprising:

a. providing a duct in said first material,

b. lining said duct with a second material, and

c. removing said first material from around said second material leaving a micro-needle fabricated from said second material attached to said first material and upstanding therefrom.

25. A method according to claim 24, wherein the second material is any one of the following materials:

SiO₂, a metal, ceramic, a polymer, a semi-conductor.

26. A method according to claim 24 wherein a portion of the second material covering the inside surface of the duct is removed before or whilst the first material is removed from around the second material.

27. A method according to claim 24 wherein the first material is removed by etching.

28. A method according to claim 24 wherein a mask is lithographically provided on a substrate of the first material prior to the formation of the duct.

29. A method according to claim 28 wherein the mask is subsequently u used to control fabrication of the duct.

30. A method according to claim 24 wherein the duct is fabricated using any one of the following processes:

plasma based etching, laser ablation, focused ion beam milling, light assisted anodisation of silicon.

31. A method according to claim 24 wherein the second material is provided by any one of the following processes:

oxidiation, deposition.

32. A method according to claim 24 wherein the micro-needle is shaped by removing a portion of the second material.