Method of molding a microneedle

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;

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

sidewalls having an overflow vent and an injection gate and the polymeric material is injected through the injection gate into the closed mold apparatus;

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;

wherein the mold insert has a mold insert height and the molded microneedle has a height that is from about 90% of the mold insert height to about 115% of the mold insert height; and

wherein the mold insert has the negative image of a plurality of microneedles in the form of an array comprising a plurality of microneedles integrally formed with a substrate.

2. A method as claimed in claim 1 wherein the negative image of the at least one microneedle is substantially completely filled with injected polymeric material.

3. A method as claimed in claim 1 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.

4. A method as claimed in claim 3 wherein the negative image of the at least one microneedle is substantially completely filled with the injected polymeric material during the compressing step.

5. A method as claimed in claim 1 wherein a wedge is used to move the compression core towards the mold insert.

6. A method as claimed in claim 5 wherein the wedge is moved in a direction orthogonal to the motion of the compression core.

7. A method as claimed in claim 1 wherein the compression core is moved a distance of between 0.002 inches (50.8 μm) to 0.010 inches (254 μm) towards the mold insert.

8. A method as claimed in claim 1 wherein the polymeric material is selected from the group consisting of polycarbonate, polyetherimide, polyethylene terephthalate, and a mixture thereof.

9. A method as claimed in claim 1 wherein the polymeric material is polycarbonate.

10. A method as claimed in claim 1 wherein the compressive force applied to the mold cavity during the compressing step is greater than 5000 psi (34500 kPa).

11. A method as claimed in claim 1 wherein the mold insert has the negative image of a plurality of arrays.

12. A method as claimed in claim 1 , 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.

13. A method as claimed in claim 12 , wherein the non-patterned substrate has an area of more than about 0.10 square inch (0.65 cm 2 ) and less than about 1 square inch (6.5 cm 2 ).

14. A method as claimed in claim 1 , wherein the microneedle array comprises a plurality of microneedles having a substantially pyramidal shape.

15. A method as claimed in claim 1 wherein the mold insert is held at a substantially constant temperature during the injecting, compressing, and opening steps.

16. A method as claimed in claim 1 , 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.

17. A method as claimed in claim 1 , further comprising 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.