Patch production
A method of producing projections on a patch including providing a mask on a substrate and etching the substrate using an etchant and a passivant to thereby control the etching process and form the projections, wherein the passivant does not include oxygen.
1. A method of producing projections on a patch, the method including:
a) providing a mask on a substrate; and,
b) etching the substrate using a mixture of an etchant and a passivant to thereby control the etching process and form the projections, wherein the etching process is controlled by varying a ratio of the etchant to the passivant in the mixture, wherein the ratio is in the range of 0.25 to 0.60, and wherein the passivant does not include oxygen.
2. A method according to claim 1 , wherein the mask includes an organic photo-resist.
3. A method according to claim 1 , wherein the passivant is a gas including:
a) at least one of:
i) carbon; and,
ii) silicon; and,
b) at least one of:
i) chlorine; and,
ii) fluorine.
4. A method according to claim 1 , wherein the passivant is at least one of:
a) a per-fluoride hydrocarbon;
b) a fluorinated olefine;
c) Octafluorocyclobutane;
d) Perfluoroisobutene; and,
e) C 4 F 8 .
5. A method according to claim 1 , wherein the etchant is a gas or plasma.
6. A method according to claim 1 , wherein the etchant is sulfur hexa-fluoride.
7. A method according to claim 1 , wherein the method includes, controlling the etching process by varying etching parameters including at least one of:
a) a gas flow for at least one of the etchant and the passivant; and,
b) a pressure for at least one of the etchant and the passivant.
8. A method according to claim 7 , wherein the pressure of at least one of the etchant and the passivant is in the range of 0 to 26.7 Pa.
9. A method according to claim 7 , wherein the pressure of at least one of the etchant and the passivant is in the range of 0.67 to 8.0 Pa.
10. A method according to claim 7 , wherein the etchant is supplied at a flow rate in the range of 0 to 200 sccm.
11. A method according to claim 1 , wherein the passivant is supplied at a flow rate in the range of 0 to 200 sccm.
12. A method according to claim 1 , wherein the method includes:
a) applying a mask material to the substrate; and,
b) selectively exposing the mask material to radiation to thereby form the mask.
13. A method according to claim 12 , wherein the mask material is at least one of:
a) an organic photo-resist;
b) a polymer mask; and,
c) a crosslinked epoxy resin.
14. A method according to claim 12 , wherein the mask material is Su-8.
15. A method according to claim 1 , wherein the method includes, performing post-etch processing.
16. A method according to claim 15 , wherein the method includes, chemically sharpening the projections.
17. A method according to claim 15 , wherein the method includes, sharpening the projections by:
a) forming a silicon dioxide layer on the projections; and,
b) removing the silicon dioxide layer.
18. A method according to claim 17 , wherein the method includes forming a silicon dioxide layer on the projections by heating the projections in an oxygen rich environment.
19. A method according to claim 18 , wherein the method includes heating the projections to a temperature of greater than 1000° C.
20. A method according to claim 17 , wherein the method includes removing the silicon dioxide using 10% HF.
21. A method according to claim 1 , wherein the method includes, applying a coating to the projections.
22. A method according to claim 21 , wherein the coating is a metallic coating.
23. A method according to claim 21 , wherein the method includes using sputter deposition to deposit:
a) an adhesion layer; and,
b) a metallic layer on the adhesion layer.
24. A method according to claim 23 , wherein the adhesion layer includes chromium.
25. A method according to claim 22 , wherein the metallic coating includes gold.
26. A method according to claim 1 , wherein the method further includes coating the projections with a material.
27. A method according to claim 26 , wherein the material is a therapeutic agent.
28. A method according to claim 1 , wherein the patch has a surface area of approximately 0.4 cm 2 .
29. A method according to claim 1 , wherein the projections have a density of between 1,000-30,000 projections/cm 2 .
30. A method according to claim 1 , wherein the projections have a density of 20,000 projections/cm 2 .
31. A method according to claim 1 , wherein the projections have a length of between 10 to 200 μm.
32. A method according to claim 1 , wherein the projections have a length of 90 μm.
33. A method according to claim 1 , wherein the projections have a radius of curvature of greater than 1 μm.
34. A method according to claim 1 , wherein the projections have a radius of curvature greater than 5 μm.
35. A method according to claim 1 , wherein the projections include a support section and a targeting section.
36. A method according to claim 35 , wherein the targeting section has a diameter of less than 1 μm.
37. A method according to claim 35 , wherein a length for the targeting section is less than 2.0 μm.
38. A method according to claim 35 , wherein a length for the support section is at least one of:
a) for epidermal delivery <200 μm;
b) for dermal cell delivery <1000 μm;
c) for delivery to basal cells in the epithelium of the mucosa 600-800 μm; and,
d) for lung delivery of the order of 100 μm an in this case.