Method of molding a microneedle
View Patent ↗A method of molding a microneedle using a mold apparatus that includes the use of high frequency acoustic energy, such as ultrasonic energy.
1. 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;
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) applying acoustic energy having a frequency greater than about 5,000 Hz to the mold apparatus;
(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 the molded microneedle from the mold.
2. A method as claimed in claim 1 wherein the acoustic energy is ultrasonic energy that is applied to the mold insert.
3. A method as claimed in claim 1 , wherein the polymeric material is polycarbonate.
4. 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).
5. A method as claimed in claim 1 wherein the mold insert has the negative image of a plurality of microneedles in the form of an array.
6. A method as claimed in claim 5 wherein the mold insert has the negative image of a plurality of arrays.
7. A method as claimed in claim 5 wherein the molded microneedle is formed as part of a microneedle array comprising a plurality of microneedles integrally formed with a substrate.
8. A method as claimed in claim 5 , 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.
9. A method as claimed in claim 7 wherein the acoustic energy is applied in a direction perpendicular to the plane of the microneedle array.
10. A method as claimed in claim 7 wherein the acoustic energy is applied in a direction parallel to the plane of the microneedle array.
11. A method as claimed in claim 1 wherein the acoustic energy is applied by an ultrasonic horn.
12. A method as claimed in claim 11 wherein the ultrasonic horn directly contacts the injected polymeric material.
13. A method as claimed in claim 11 wherein the ultrasonic horn is cross-shaped.