Method and apparatus for producing uniform small portions of fine powders and articles thereof
A method for depositing controlled quantity of particles on a substrate comprises providing aerosolized particles in a deposition zone having first and second electrodes, and creating an electrostatic field between the first electrode and the second electrode to create a pool of ions at the first electrode, charging particles within the deposition zone with the ions, and moving the particles towards and depositing the particles onto the substrate. In order to prevent excessive charge build up on the substrate, the electrostatic field is periodically reversed.
1. A method for depositing a controlled quantity of dry powder pharmaceutical particles on a dielectric substrate, comprising the steps of:
(a) providing aerosolized dry powder pharmaceutical particles to a deposition zone having first and second electrodes, wherein the second electrode is closer to the substrate than the first electrode;
(b) providing a pool of ions of positive and negative polarities adjacent to the first electrode;
(c) creating an electrostatic field between the first electrode and the second electrode to drive at least some of the ions from the first electrode towards the second electrode;
(d) charging dry powder particles within the deposition zone with ions that are being driven from the first electrode to the second electrode whereupon the charged dry powder particles are moved towards and deposited on the substrate by the electrostatic field; and
(e) periodically reversing the electrostatic field to alternately drive ions of opposite polarities from the pool to prevent excessive charge build up on the substrate and in the dry powder particles deposited thereon.
2. The method according to claim 1 , wherein said aerosolized particles comprise carrier particles coated with a bioactive agent.
3. The method according to claim 1 , wherein said aerosolized particles are charged in a location within the deposition zone.
4. The method according to claim 1 , wherein said substrate comprises an edible material.
5. The method according to claim 4 , wherein the substrate is incorporated into a blister, tablet, capsule or tublet.