Method and apparatus for coating skin piercing microprojections
An apparatus and method are provided for selectively applying an agent-containing liquid coating to extremely tiny skin piercing microprojections ( 10 ). The coating solution is applied to the skin piercing microprojections ( 10 ) using a coating technique which selectively coats only the skin piercing microprojections ( 10 ) and not the substrate ( 12 ) from which the microprojections ( 10 ) extend, and then dried. The coating method includes providing an agent-containing coating liquid and conveying the liquid to a liquid holding surface having a coating transfer region. The depth of the coating liquid at the coating transfer region is precisely controlled. The microprojections are then immersed to a predetermined level in the coating liquid. The liquid that coats the microprojections ( 10 ) is then dried to form a solid agent-containing coating on the microprojections ( 10 ).
1. An apparatus for applying an agent-containing coating liquid onto a plurality of microprojections extending from a surface or edge of a substrate substantially without coating said substrate, comprising:
a rotatable member with a liquid holding surface, said liquid holding surface having a coating transfer region;
a coating liquid conveyor for providing said coating liquid at said coating transfer region;
a coating liquid depth controller for controlling the depth of said coating liquid at said coating transfer region to a predetermined depth; and
a substrate conveyor for conveying said microprojections at a predetermined level of immersion through said coating liquid at said coating transfer region, wherein said substrate conveyor comprises a track which is adjustably positionable to a predetermined distance from said coating transfer region and a substrate holding sled which runs along said track.