Method Of Molding A Microneedle

• US 20080088066A1
• Filed: 12/07/2005
• Published: 04/17/2008
• Est. Priority Date: 12/07/2004
• Status: Active Grant

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Ferguson, Dennis, Pochardt, Donald, Nayar, Satinder
• Granted Patent: US 8,088,321 B2
• Time in Patent Office: Days
• US Class Current: 264/443
• CPC Class Codes: A61M 2037/0053 Methods for producing microneedles
• CPC Class Codes: A61M 37/0015 by using microneedles
• CPC Class Codes: B29C 2045/0094 injection moulding of small-sized articles, e.g. microarticles, ultra thin articles
• CPC Class Codes: B29C 2791/008 Using vibrations during moulding
• CPC Class Codes: B29C 45/2669 with means for removing excess material, e.g. with overflow cavities B29C45/1711 takes precedence
• CPC Class Codes: B29C 45/34 having venting means
• CPC Class Codes: B29C 45/561 Injection-compression moulding
• CPC Class Codes: B29C 45/568 Applying vibrations to the mould parts
• CPC Class Codes: B29L 2031/7544 Injection needles, syringes
• CPC Class Codes: B29L 2031/756 Microarticles, nanoarticles

Abstract

A method of molding a microneedle using a mold apparatus that comprises a mold insert having the negative image of at least one microneedle, a compression core, and a mold housing configured to allow a reciprocal motion between the mold insert and the compression core. The mold apparatus has an open position and a closed position. The mold apparatus is placed in the closed position and polymeric material is injected into the closed mold apparatus. The injected polymeric material is compressed between the mold insert and the compression core by a reciprocal motion between the compression core and the mold insert. Also, molding methods wherein the mold apparatus has sidewalls having an injection gate. Also, molding methods comprising a heated mold insert. Also, molding methods comprising the application of ultrasonic energy to the mold apparatus.

Claims

1. A method of molding a microneedle comprising:

(i) providing a mold apparatus comprising;

a mold insert having the negative image of at least one microneedle;

a compression core;

sidewalls having an injection gate; and

a mold housing configured to allow a reciprocal motion between the mold insert and the compression core;

wherein the mold apparatus has an open position and a closed position;

(ii) placing the mold apparatus in the closed position;

(iii) injecting polymeric material through the injection gate into the closed mold apparatus;

(iv) compressing the injected polymeric material between the mold insert and the compression core by a reciprocal motion between the compression core and the mold insert;

(v) opening the mold; and

(vi) removing a molded microneedle from the mold.

2. A method according to claim 1 further comprising the step of heating the mold insert to a temperature of greater than or equal to 200°

F. (93.3°

C.) before the polymeric material is injected through the injection gate into the closed mold apparatus.

3. A method according to claims 1 or 2 wherein the sidewalls further comprise an overflow vent.

5. A method according to any of the preceding claims wherein the negative image of the at least one microneedle is substantially completely filled with injected polymeric material.

6. A method according to any of the preceding claims wherein the injected polymeric material has a melt-flow index greater than about 5 g/10 minutes at conditions of 300°

C. and 1.2 kg weight.

8. A method according to any of the preceding claims wherein a wedge is used to move the compression core towards the mold insert.

9. A method according to claim 8 wherein the wedge is moved in a direction orthogonal to the motion of the compression core.

10. A method according to any of the preceding claims wherein the compression core is moved a distance of between 0.002 inches (50.8 μ

m) to 0.010 inches (254 μ

m) towards the mold insert.

11. A method according to any of the preceding claims wherein the polymeric material is selected from the group consisting of polycarbonate, polyetherimide, polyethylene terephthalate, and a mixture thereof.

12. A method according to claim 11 wherein the polymeric material is polycarbonate.

13. A method according to any of the preceding claims wherein the compressive force applied to the mold cavity during the compressing step is greater than 5000 psi (34500 kPa).

14. A method according to any of the preceding claims wherein the mold insert has the negative image of a plurality of microneedles in the form of an array.

15. A method according to claim 14 wherein the mold insert has the negative image of a plurality of arrays.

16. A method according to claims 14 or 15 wherein the molded microneedle is formed as part of a microneedle array comprising a plurality of microneedles integrally formed with a substrate.

17. A method according to claim 16, wherein the microneedle array comprises a plurality of microneedles having a substantially flat tip comprising a surface area measured in a plane aligned with the base of about 20 square micrometers or more and 100 square micrometers or less.

18. A method according to any of claims 16 or 17, wherein the microneedle array is formed as part of a larger array, wherein at least a portion of the larger array comprises a non-patterned substrate.

19. A method according to claim 18, wherein the non-patterned substrate has an area of more than about 0.10 square inch (0.65 cm²) and less than about 1 square inch (6.5 cm²).

20. A method according to any of claims 16 to 19, wherein the microneedle array comprises a plurality of molded microneedles having a height greater than about 95 percent of the corresponding height of the microneedle topography in the mold insert.

21. A method according to any of claims 16 to 20, wherein the microneedle array comprises a plurality of microneedles having a substantially pyramidal shape.

22. A method according to any of the preceding claims further comprising the addition of ultrasonic energy to the mold apparatus during the injecting step.

23. A method according to any of the preceding claims further comprising the addition of ultrasonic energy to the mold apparatus during the compressing step.

24. A method according to any of the preceding claims wherein the mold insert is held at a substantially constant temperature during the injecting, compressing, and opening steps.

4. A method of molding a microneedle comprising:

(i) providing a mold apparatus comprising;

a mold insert having the negative image of at least one microneedle;

a compression core; and

a mold housing configured to allow a reciprocal motion between the mold insert and the compression core;

wherein the mold apparatus has an open position and a closed position;

(ii) heating the mold insert to a temperature of greater than or equal to 200°

F. (93.3°

C.);

(iii) placing the mold apparatus in the closed position;

(iv) injecting polymeric material into the closed mold apparatus;

(v) compressing the injected polymeric material between the mold insert and the compression core by a reciprocal motion between the compression core and the mold insert;

(vi) opening the mold; and

(vii) removing a molded microneedle from the mold.

7. A method of molding a microneedle comprising:

(i) providing a mold apparatus comprising;

a mold insert having the negative image of at least one microneedle;

a compression core; and

a mold housing configured to allow a reciprocal motion between the mold insert and the compression core;

wherein the mold apparatus has an open position and a closed position;

(ii) placing the mold apparatus in the closed position;

(iii) injecting polymeric material into the closed mold apparatus, wherein the polymeric material is characterized by a melt-flow index greater than about 5 g/10 minutes when measured at conditions of 300°

C. and 1.2 kg weight;

(iv) compressing the injected polymeric material between the mold insert and the compression core by a reciprocal motion between the compression core and the mold insert, so that the negative image of the at least one microneedle is substantially completely filled with the injected polymeric material;

(v) opening the mold; and

(vi) removing a molded microneedle from the mold.

25. A method of molding a microneedle array comprising:

(i) providing a mold apparatus comprising a mold insert having the negative image of at least one microneedle, wherein the mold apparatus has an open position and a closed position;

(ii) placing the mold apparatus in the closed position;

(iii) applying ultrasonic energy to the mold apparatus;

(iv) injecting polymeric material into the closed mold apparatus;

(v) opening the mold; and

(vi) removing the molded microneedle array from the mold.

26. A method according to claim 25 wherein the ultrasonic energy is applied to the mold insert.

27. A method of molding a microneedle comprising:

(i) providing a mold apparatus comprising;

a mold insert having the negative image of at least one microneedle;

a compression core; and

a mold housing configured to allow a reciprocal motion between the mold insert and the compression core;

wherein the mold apparatus has an open position and a closed position;

(ii) placing the mold apparatus in the closed position;

(iii) injecting polymeric material into the closed mold apparatus;

(iv) compressing the injected polymeric material between the mold insert and the compression core by a reciprocal motion between the compression core and the mold insert;

(v) opening the mold; and

(vi) removing a molded microneedle from the mold.

28. A method according to claim 27 wherein the mold apparatus further comprises sidewalls having an injection gate and the polymeric material is injected through the injection gate into the closed mold apparatus.

29. A method according to claim 28 further comprising the step of heating the mold insert to a temperature of greater than or equal to 200°

F. (93.3°

C.) before the polymeric material is injected through the injection gate into the closed mold apparatus.

30. A method according to claim 28 wherein the sidewalls further comprise an overflow vent.

31. A method according to claim 27 wherein the injected polymeric material has a melt-flow index greater than about 5 g/10 minutes at conditions of 300°

C. and 1.2 kg weight.

32. A method according to claim 27 wherein the negative image of the at least one microneedle is substantially completely filled with injected polymeric material.

33. A method according to claim 27 wherein a wedge is used to move the compression core towards the mold insert.

34. A method according to claim 33 wherein the wedge is moved in a direction orthogonal to the motion of the compression core.

35. A method according to claim 27 wherein the compression core is moved a distance of between 0.002 inches (50.8 μ

m) to 0.010 inches (254 μ

m) towards the mold insert.

36. A method according to claim 27 wherein the polymeric material is selected from the group consisting of polycarbonate, polyetherimide, polyethylene terephthalate, and a mixture thereof.

37. A method according to claim 36 wherein the polymeric material is polycarbonate.

38. A method according to claim 27 wherein the compressive force applied to the mold cavity during the compressing step is greater than 5000 psi (34500 kPa).

39. A method according to claim 27 wherein the mold insert has the negative image of a plurality of microneedles in the form of an array.

40. A method according to claim 39 wherein the mold insert has the negative image of a plurality of arrays.

41. A method according to claim 39 wherein the molded microneedle is formed as part of a microneedle array comprising a plurality of microneedles integrally formed with a substrate.

42. A method according to claim 41, wherein the microneedle array comprises a plurality of microneedles having a substantially flat tip comprising a surface area measured in a plane aligned with the base of about 20 square micrometers or more and 100 square micrometers or less.

43. A method according to claim 41, wherein the microneedle array is formed as part of a larger array, wherein at least a portion of the larger array comprises a non-patterned substrate.

44. A method according to claim 43, wherein the non-patterned substrate has an area of more than about 0.10 square inch (0.65 cm²) and less than about 1 square inch (6.5 cm²).

45. A method according to any of claim 41, wherein the microneedle array comprises a plurality of molded microneedles having a height greater than about 95 percent of the corresponding height of the microneedle topography in the mold insert.

46. A method according to claim 41, wherein the microneedle array comprises a plurality of microneedles having a substantially pyramidal shape.

47. A method according to claim 27 further comprising the addition of ultrasonic energy to the mold apparatus during the injecting step.

48. A method according to claim 27 further comprising the addition of ultrasonic energy to the mold apparatus during the compressing step.

49. A method according to claim 29 wherein the mold insert is held at a substantially constant temperature during the injecting, compressing, and opening steps.

50. A method of molding a microneedle comprising:

(i) providing a mold apparatus comprising;

a mold insert having the negative image of at least one microneedle;

a compression core;

sidewalls having an injection gate; and

a mold housing configured to allow a reciprocal motion between the mold insert and the compression core;

wherein the mold apparatus has an open position and a closed position;

(ii) heating the mold insert to a temperature of greater than or equal to 200°

F. (93.3°

C.);

(iii) placing the mold apparatus in the closed position;

(iv) injecting polymeric material through the injection gate into the closed mold apparatus;

(v) compressing the injected polymeric material between the mold insert and the compression core by a reciprocal motion between the compression core and the mold insert;

(vi) opening the mold; and

(vii) removing a molded microneedle from the mold,

wherein the mold insert is held at a substantially constant temperature during the injecting, compressing, and opening steps.

51. A method of molding a microneedle comprising:

(i) providing a mold apparatus comprising;

a mold insert having the negative image of at least one microneedle;

a compression core;

sidewalls having an injection gate; and

a mold housing configured to allow a reciprocal motion between the mold insert and the compression core;

wherein the mold apparatus has an open position and a closed position;

(ii) heating the mold insert to a temperature of greater than or equal to 200°

F. (93.3°

C.);

(iii) placing the mold apparatus in the closed position;

(iv) injecting polycarbonate through the injection gate into the closed mold apparatus;

(v) compressing the injected polycarbonate between the mold insert and the compression core by a reciprocal motion between the compression core and the mold insert;

(vi) opening the mold; and

(vii) removing a molded microneedle from the mold,

wherein the mold insert is held at a substantially constant temperature during the injecting, compressing, and opening steps.