Patent ID: 7951428

Claim:
A method of coating at least a portion of an object, the method comprising: providing an object in a defined volume, the defined volume being defined by an enclosure, wherein the object comprises at least one surface; providing one or more nozzle structures, wherein each nozzle structure comprises at least an inner opening and an outer opening concentric with the inner opening, wherein the inner opening and the outer opening terminate at the dispensing end of each nozzle structure; and applying an open matrix coating to the at least one surface of the object, wherein applying the open matrix coating comprises: providing a first flow of a liquid spray composition to the inner opening, wherein the first flow of liquid spray composition comprises at least one of a biologically active ingredient, a polymer, and a solvent; providing a second flow of a liquid diluent composition to the outer opening, wherein the second flow of the liquid diluent composition comprises at least one polar solvent, and further wherein the liquid diluent composition has a dielectric constant equal to or greater than 10; generating a plurality of charged coating particles forward of the dispensing end of each nozzle structure to apply a coating to the at least one surface of the object, wherein generating the plurality of charged coating particles comprises dispensing a stream of a plurality of microdroplets having an electrical charge associated therewith from the dispensing end of each nozzle structure by creating a cone-jet from the first and second flow at the dispensing end of each nozzle using a nonuniform electrical field between the dispensing end of each nozzle structure and the object, wherein the plurality of charged coating particles having a nominal diameter of less than 10 micrometers are formed as the microdroplets evaporate; moving the plurality of charged coating particles towards the at least one surface of the object to apply the coating thereon using the nonuniform electrical field created between the dispensing end of each nozzle structure and the object; and controlling a flow rate of the second flow of the liquid diluent composition relative to a flow rate of the first flow of the liquid spray composition such that the plurality of charged coating particles forms the open matrix coating on the at least one surface of the object, wherein the flow rate of the second flow of the liquid diluent composition to the outer opening is less than 5 times the flow rate of the first flow of the liquid spray composition to the inner opening.