Metallic microneedles

1. A method for fabricating a first microneedle and a second microneedle, the method comprising:

providing a mold pillar;

forming an electrically-conductive layer over the mold pillar by:

applying a solution onto the mold pillar, the solution comprising a polymer and conductive particles dissolved in a solvent; and

evaporating the solvent from the mold pillar to leave behind the electrically-conductive layer on the mold pillar;

depositing a first metal layer over the electrically-conductive layer to provide a first microneedle;

removing the first microneedle from the mold pillar; and

depositing a second metal layer over the mold pillar to provide a second microneedle;

wherein depositing the first metal layer over the electrically-conductive layer comprises using the electrically-conductive layer as an electrode and electroplating the first metal layer onto the electrically-conductive layer.

2. The method of claim 1 wherein the mold pillar comprises a protective layer for protecting the mold pillar from subsequent processes and enabling use of the mold pillar for fabricating a plurality of microneedles.

3. The method of claim 1 wherein forming the electrically-conductive layer over the mold pillar comprises using a spray deposition process.

4. The method of claim 1 wherein the electrically-conductive layer comprises an apertured electrically-conductive layer.

5. The method of claim 4 comprising forming the apertured electrically-conductive layer by removing a portion of the electrically-conductive layer to form an aperture.

6. The method of claim 5 comprising removing the portion of the electrically-conductive layer by one or more of: dry etching, photolithography, mechanical grinding, and localized heating.

7. The method of claim 1 wherein removing the first microneedle from the mold pillar comprises at least partially dissolving the electrically-conductive layer.

8. The method of claim 1 comprising forming a sacrificial layer between the mold pillar and the electrically-conductive layer and wherein removing the first microneedle from the mold pillar comprises at least partially dissolving the sacrificial layer.

9. The method of claim 1 wherein depositing the second metal layer over the mold pillar to provide the second microneedle comprises depositing the second metal layer over the electrically-conductive layer to provide the second microneedle.

10. The method of claim 1 wherein depositing the second metal layer over the mold pillar to provide the second microneedle comprises:

forming a second electrically-conductive layer over the mold pillar; and

depositing the second metal layer over the second electrically-conductive layer to provide the second microneedle.

11. The method of claim 1 wherein removing the first microneedle from the mold pillar leaves the mold pillar substantially intact.

12. A method for fabricating a first microneedle and a second microneedle, the method comprising:

providing a mold pillar;

forming an electrically-conductive layer over the mold pillar by:

applying a solution onto the mold pillar, the solution comprising a polymer and conductive particles dissolved in a solvent; and

evaporating the solvent from the mold pillar to leave behind the electrically-conductive layer on the mold pillar;

depositing a first metal layer over the electrically-conductive layer to provide a first microneedle;

removing the first microneedle from the mold pillar; and

depositing a second metal layer over the mold pillar to provide a second microneedle;

wherein the electrically-conductive layer comprises an apertured electrically-conductive layer; and

forming the apertured electrically-conductive layer by:

applying a coating to a region of the mold pillar before forming the electrically-conductive layer over the mold pillar; and

choosing the solvent such that the solvent is repelled by the coating so that the electrically-conductive layer is created with an aperture located at the coated region.

13. The method of claim 12 wherein:

depositing the first metal layer over the electrically-conductive layer comprises sputtering the first metal layer over the electrically-conductive layer; and

removing the first microneedle from the mold pillar comprises at least partially dissolving the electrically-conductive layer.

14. A method for fabricating a first microneedle and a second microneedle, the method comprising:

providing a mold pillar;

forming an electrically-conductive layer over the mold pillar by:

applying a solution onto the mold pillar, the solution comprising a polymer and conductive particles dissolved in a solvent; and

evaporating the solvent from the mold pillar to leave behind the electrically-conductive layer on the mold pillar;

depositing a first metal layer over the electrically-conductive layer to provide a first microneedle;

removing the first microneedle from the mold pillar; and

depositing a second metal layer over the mold pillar to provide a second microneedle;

wherein the electrically-conductive layer comprises an apertured electrically-conductive layer; and

forming the apertured electrically-conductive layer by:

orienting the mold pillar so that a first region of the mold pillar is vertically higher than a second region of the mold pillar such that the force of gravity causes the electrically-conductive layer to form with an aperture at the first region.