# US 8,771,793 B2 · Vacuum assisted slot die coating techniques > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,771,793 B2 - Document ID: US8771793B2 - Status: Granted - Kind: B2 - Application number: 13/088,078 - Filed: 2011-04-15 - Published: 2012-10-18 - Granted: 2014-07-08 - Earliest claimed: 2011-04-15 - Assignees: Roche Diagnostics Operations, Inc. - Applicants: Christopher D. Wilsey; Abner D. Joseph; Sergio Buccilli - Inventors: Christopher D. Wilsey; Abner D. Joseph; Sergio Buccilli - Web page: https://patentgrep.com/patent/US8771793B2 ## CPC - B05C 5/0254: {Coating heads with slot-shaped outlet (B05C5/0283 takes precedence)} - B05C 11/10: Storage, supply or control of liquid or other fluent material; Recovery of excess liquid or other fluent material {(B05C1/0813, B05C5/0225, B05C17/002 and B05C19/06 take precedence)} - B05C 11/1005: {responsive to condition of liquid or other fluent material already applied to the surface, e.g. coating thickness, weight or pattern} - B05D 1/265: {Extrusion coatings} - G01N 27/3272: {Test elements therefor, i.e. disposable laminated substrates with electrodes, reagent and channels (optical biosensors G01N33/52)} - B05D 3/0493: {using vacuum} - B05C: APPARATUS FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL (spraying apparatus, atomising apparatus, nozzles B05B; plant for applying liquids or other fluent materials to objects by electrostatic spraying B05B5/08) - B05D: PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL (conveying articles or workpieces through baths of liquid B65G, e.g. B65G49/02) - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) ## Abstract Systems, apparatuses, techniques and processes for applying a wet film to a substrate using a slot die are provided. In one form, the air pressure around at least a portion of the discharge end of the slot die is adjustable by the application of a vacuum force in order to control the width and thickness of the wet film being applied to the substrate. In one aspect of this form, the wet film is a narrow, continuous stripe of reagent material applied to a moving web of the substrate from which a plurality of test elements will be obtained. However, different forms and applications are also envisioned. ## Claims ### Claim 1 A method for applying a wet film to a substrate, comprising: applying a coating material at a discharge rate about 2 ml/min to about 20 ml/min from a discharge end of a slot die onto a moving web of said substrate at a moving rate of about 10.0 m/min to about 45.0 m/min to form said wet film on said substrate, said wet film including a width and a thickness relative to said substrate, wherein said discharge end of said slot die comprises an upstream bar and a downstream bar each bar having an essentially planar land surface facing said moving web, and wherein a constant coating gap of about 40 μm to about 450 μm is maintained between said discharge end of said slot die and said moving web; applying a vacuum force adjacent said discharge end of said slot die, wherein said vacuum force creates a pressure differential between an upstream side of said discharge end and a downstream side of said discharge end, and wherein said pressure differential is between about 1 inch of H20 and about 10 inches of H20; and adjusting said vacuum force in real-time while applying said coating material to control said width and thickness of said wet film. ### Claim 2 A method for applying a wet film to a substrate, comprising: applying a coating material at a discharge rate about 2 ml/min to about 20 ml/min from a discharge end of a slot die onto a moving web of said substrate at a moving rate of about 10.0 m/min to about 45.0 m/min to form said wet film on said substrate, said wet film including a width and a thickness relative to said substrate, wherein said discharge end of said slot die comprises an upstream bar and a downstream bar, each bar having an essentially planar land surface facing said moving web, and wherein a constant coating gap of about 40 μm to about 450 μm is maintained between said discharge end of said slot die and said moving web; applying a vacuum force adjacent said discharge end of said slot die, wherein said vacuum force creates a pressure differential between an upstream side of said discharge end and a downstream side of said discharge end, and wherein said pressure differential is between about 1 inch of H20 and about 10 inches of H20; adjusting said vacuum force in real-time while applying said coating material to control said width and thickness of said wet film; and sensing said width of said wet film, and wherein adjusting said vacuum force is performed in response to determining said width corresponds to a value other than a predetermined value. ### Claim 3 (depends on 2) The method of claim 2, wherein said predetermined value is about 5 millimeters. ### Claim 4 (depends on 2) The method of claim 2, wherein said predetermined value is about 7 millimeters. ### Claim 5 (depends on 2) The method of claim 2, wherein said predetermined value is between about 4.7 millimeters and about 5.3 millimeters. ### Claim 6 (depends on 2) The method of claim 2, wherein said predetermined value is between about 6.7 millimeters and about 7.5 millimeters. ### Claim 7 (depends on 1) The method of claim 1, wherein said substrate is formed of a polymer material on which a plurality of electrode patterns is positioned. ### Claim 8 (depends on 7) The method of claim 7, which includes applying said coating material from said discharge end of said slot die over said electrode patterns to form said wet film on said electrode patterns. ### Claim 9 (depends on 1) The method of claim 1, wherein applying said vacuum force includes positioning a vacuum box adjacent said discharge end of said slot die, said vacuum box including a pair of vacuum outlets positioned opposite one another and upstream from said wet film. ### Claim 10 (depends on 1) The method of claim 1, wherein said coating gap is between about 40 μm and about 200 μm. ### Claim 11 (depends on 1) The method of claim 1, wherein said coating material includes a reagent for producing an electrochemical signal in the presence of a test analyte. ### Claim 12 (depends on 11) The method of claim 11, wherein said test analyte is glucose and said reagent includes at least one of an enzyme, co-enzyme and co-factor. ### Claim 13 (depends on 1) The method of claim 1, wherein said thickness of said wet film is between about 40 μm and about 100 μm. ### Claim 14 (depends on 1) The method of claim 1, which further includes drying said wet film to provide a dried layer of said coating material on said substrate, said dried layer of said coating material including a dried thickness between about 3 μm and about 20 μm. ### Claim 15 (depends on 1) The method of claim 1, wherein said discharge rate is about 2 ml/min to about 4 ml/min. ### Claim 16 (depends on 1) The method of claim 1, wherein said moving rate is about 10 m/min. ### Claim 17 (depends on 1) The method of claim 1, wherein said coating gap is about 190 μm. ### Claim 18 (depends on 1) The method of claim 1, wherein said pressure differential is about 2 inches of H20 to about 6 inches of H20.