Electrospray coating of objects

Abstract

Electrospray methods and systems for coating of objects (e.g., medical devices such as a stent structure) with selected types of coatings (e.g., open matrix coating and closed film coating)

1 - 42 . (canceled) 
     
     
         43 . A method of coating at least a portion of an object, the method comprising:
 providing an object in a defined volume, wherein the object comprises at least one surface;   providing one or more nozzle structures, wherein each nozzle structure comprises one or more openings terminating at a dispensing end of each nozzle structure;   providing one or more flows of liquid compositions to the openings;   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 one or more flows 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, wherein using the nonuniform electrical field between the dispensing end of each nozzle structure and the object to generate the plurality of charged coating particles comprises applying an electrical potential difference between the dispensing end of each nozzle structure and the object being coated so as to create the cone jet from the one or more flows at the dispensing end of each nozzle structure; and   adjusting the electrical potential difference between the dispensing end of each nozzle structure and the object being coated as the thickness of the coating increases so as to maintain a stable cone jet at the dispensing end of each nozzle structure.   
     
     
         44 . The method of  claim 43 , wherein the coating applied on the at least one surface of the object is a uniform open matrix coating. 
     
     
         45 . The method of  claim 43 , wherein the coating applied on the at least one surface of the object is a uniform closed film coating. 
     
     
         46 . The method of  claim 43 , wherein providing the one or more flows comprises providing a first flow of a liquid spray composition at an inner opening terminating at the dispensing end, wherein the liquid spray composition comprises at least a biologically active ingredient, a polymer, and a solvent suitable to at least partially dissolve the polymer, and further providing a second flow of a liquid diluent composition at an outer opening terminating at the dispensing end concentric with the inner opening, wherein the liquid diluent composition has a high dielectric constant. 
     
     
         47 . The method of  claim 43 , wherein adjusting the electrical potential difference between the dispensing end of each nozzle structure and the object being coated further comprises:
 detecting at least one characteristic associated with the cone-jet;   determining the stability of the cone jet based on the at least one characteristic; and   adjusting one or more process parameters to maintain a stable cone-jet.   
     
     
         48 . The method of  claim 47 , wherein detecting at least one characteristic associated with the cone jet comprises imaging the cone jet to determine at least one angle associated therewith. 
     
     
         49 . The method of  claim 47 , wherein detecting at least one characteristic associated with the cone-jet comprises detecting one or more flutters in the cone-jet. 
     
     
         50 . The method of  claim 47 , wherein detecting at least one characteristic associated with the cone jet comprises imaging the cone-jet to detect bubbles in at least one of the flows. 
     
     
         51 . The method of  claim 43 , wherein the plurality of coating particles have a nominal diameter of greater than about 1 nanometer and less than about 500 nanometers. 
     
     
         52 . A method of coating at least a portion of an object, the method comprising:
 providing an object in a defined volume, wherein the object comprises at least one surface;   providing one or more nozzle structures, wherein each nozzle structure comprises one or more openings terminating at a dispensing end of each nozzle structure;   providing one or more flows of liquid compositions to the openings;   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 one or more flows at the dispensing end of each nozzle structure 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 fanned as the microdroplets evaporate;   detecting at least one characteristic associated with the cone-jet;   determining the stability of the cone jet based on the at least one characteristic; and   adjusting one or more process parameters to maintain a stable cone-jet.   
     
     
         53 . The method of  claim 52 , wherein the coating applied on the at least one surface of the object is a uniform open matrix coating. 
     
     
         54 . The method of  claim 52 , wherein the coating applied on the at least one surface of the object is a uniform closed film coating. 
     
     
         55 . The method of  claim 52 , wherein providing the one or more flows comprises providing a first flow of a liquid spray composition to an inner opening terminating at the dispensing end, wherein the liquid spray composition comprises at least a biologically active ingredient, a polymer, and a solvent suitable to at least partially dissolve the polymer, and further providing a second flow of a liquid diluent composition to an outer opening terminating at the dispensing end concentric with the inner opening, wherein the liquid diluent composition has a high dielectric constant. 
     
     
         56 . The method of  claim 52 , wherein detecting at least one characteristic associated with the cone-jet comprises imaging the cone jet to determine at least one angle associated therewith. 
     
     
         57 . The method of  claim 52 , wherein detecting at least one characteristic associated with the cone jet comprises detecting one or more flutters in the cone-jet. 
     
     
         58 . The method of  claim 52 , wherein detecting at least one characteristic associated with the cone jet comprises imaging the cone jet to detect bubbles in the one or more flows. 
     
     
         59 . The method of  claim 52 , wherein the plurality of coating particles have a nominal diameter of greater than about 1 nanometer and less than about 500 nanometers. 
     
     
         60 - 66 . (canceled) 
     
     
         67 . A system for coating at least a portion of an object, the system comprising:
 at least one liquid composition source;   a dispensing device configured to receive one or more flows of liquid composition from the at least one liquid composition source and dispense a plurality of microdroplets having an electrical charge associated therewith from a dispensing end of each of one or more nozzle structures into a defined volume in which the object is placed;   an electrode structure comprising an electrode isolated from the dispensing ends of the one or more nozzle structures, wherein the electrode structure is used to create a nonuniform electrical field between the dispensing end of each nozzle structure and the object to be coated, wherein the electrode structure is further used to create a cone jet from the one or more flows at the dispensing end of each nozzle structure when in operation to generate, the plurality of microdroplets; and   detection and control apparatus to adjust the electrical potential difference between the dispensing end of each nozzle structure and the object being coated as the thickness of the coating increases so as to maintain a stable cone jet at the dispensing end of each nozzle structure during coating of the object.   
     
     
         68 . The system of  claim 67 , wherein the detection and control apparatus further is configured to detect at least one characteristic associated with the cone-jet, determine the stability of the cone jet based on the at least one characteristic, and adjust one or more process parameters to maintain a stable cone-jet. 
     
     
         69 . The system of  claim 68 , wherein detection and control apparatus comprises an imaging apparatus for use in determining at least one angle associated with the cone-jet. 
     
     
         70 . The system of  claim 68 , wherein detection and control apparatus comprises an imaging apparatus for use in detecting one or more flutters in the cone-jet. 
     
     
         71 . The system of  claim 68 , wherein detection and control apparatus comprises an imaging apparatus for use in detecting bubbles in the one or more flows. 
     
     
         72 . A system for coating at least a portion of an object, the system comprising:
 at least one liquid composition source;   a dispensing device configured to receive one or more flows of liquid composition from the at least one liquid composition source and dispense a plurality of microdroplets having an electrical charge associated therewith from a dispensing end of each of one or more nozzle structures into a defined volume in which the object is placed;   an electrode structure comprising an electrode isolated from the dispensing ends of the one or more nozzle structures, wherein the electrode structure is used to create a nonuniform electrical field between the dispensing end of each nozzle structure and the object to be coated, wherein the electrode structure is further used to create a cone jet from the one or more flows at the dispensing end of each nozzle structure when in operation to generate the plurality of microdroplets; and   detection and control apparatus to detect at least one characteristic associated with the cone-jet, determine the stability of the cone-jet based on the at least one characteristic, and adjust one or more process parameters to maintain a stable cone-jet.   
     
     
         73 . The system of  claim 72 , wherein detection and control apparatus comprises an imaging apparatus for use in determining at least one angle associated with the cone-jet. 
     
     
         74 . The system of  claim 72 , wherein detection and control apparatus comprises an imaging apparatus for use in detecting one or more flutters in the cone-jet. 
     
     
         75 . The system of  claim 72 , wherein detection and control apparatus comprises an imaging apparatus for use in detect bubbles in the one or more flows. 
     
     
         76 - 80 . (canceled)