Cylindrical Magnetron Sputtering for Uniform Antimicrobial Polymer Coatings
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Solution Overview
Problem
Existing methods for applying antimicrobial coatings on textile surfaces, particularly yarns and fabrics, face challenges such as non-uniform deposition, environmental unfriendliness, high costs, and the inability to handle both yarns and fabrics in a single system, with planar magnetron sputtering being inadequate for woven fabrics and cylindrical magnetron sputtering being costly for large cathodes.
Innovation Solution
A post-cathode cylindrical magnetron sputtering process that uses a modified cylindrical magnetron assembly with a central target cathode and an outer anode, combined with a mechanical system for moving substrates, to uniformly deposit antimicrobial coatings of copper oxide on both yarns and fabrics in a single environment-friendly process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If planar magnetron sputtering is used for coating, then the process is simple and cost-effective, but it cannot uniformly coat woven fabrics and yarns
Solution Approach 1:
The patent applies a cylindrical magnetron sputtering system where the substrate (yarn or fabric) is positioned at the center of a cylindrical cathode. This curved cylindrical geometry replaces the planar geometry of conventional magnetron sputtering, enabling uniform coating around cylindrical yarns and across fabric surfaces by ensuring equidistant plasma distribution from all directions.
Solution Approach 2:
The invention transitions from two-dimensional planar sputtering to three-dimensional cylindrical sputtering. The central substrate position within the cylindrical cathode creates plasma deposition from all radial directions simultaneously, adding a dimensional aspect that enables uniform coating on complex geometries like yarns and woven fabrics that cannot be achieved with planar methods.
2Manufacturing precision
If cylindrical magnetron sputtering with large cathode is used, then uniform coating on yarns and fabrics is achieved, but the cost increases significantly
Solution Approach 1:
The cylindrical magnetron sputtering system is designed to handle multiple substrate types (yarns, woven fabrics, non-woven fabrics) in a single configuration. The central substrate positioning and radial plasma distribution mechanism works universally for different geometries, eliminating the need for separate coating systems for yarns and fabrics, thereby reducing overall manufacturing costs despite the advanced technology.
Solution Approach 2:
The patent optimizes plasma parameters including gas pressure (0.1-10 mbar), power density (10-100 W/cm²), and substrate temperature (20-200°C) to achieve uniform coating with controlled material deposition rates. By carefully controlling these parameters, the system achieves high-quality coatings while minimizing material waste and energy consumption, offsetting the higher capital cost of the cylindrical configuration.
3Reliability
If chemical methods with nanoparticles are used, then antimicrobial properties are achieved, but the process is environmentally unfriendly and coating adhesion is poor
Solution Approach 1:
The patent replaces chemical impregnation methods with physical vapor deposition through magnetron sputtering. Instead of using chemical solutions and nanoparticles that require soaking and drying processes, the system directly deposits antimicrobial metal layers (silver, copper, zinc, or their oxides) from a plasma state, eliminating chemical waste and improving adhesion through physical bonding to the substrate surface.
Solution Approach 2:
The sputtering process occurs in a vacuum environment with controlled inert or reactive gas atmosphere (typically argon with optional oxygen). This controlled atmosphere prevents unwanted chemical reactions during deposition and allows for clean, adherent coating formation. The vacuum environment also eliminates contamination that would occur with ambient chemical processing, improving both coating quality and environmental safety.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The process achieves uniform, adherent, and cost-effective antimicrobial coatings on moving yarns and fabrics, demonstrating significant bacterial and viral reduction, with a 3-log reduction in viral load and effective antimicrobial properties against Staphylococcus Aureus and Escherichia Coli, and >97% viral reduction against SARS-CoV-2.
Implementation Method 1
A post-cathode cylindrical magnetron sputtering process that uses a modified cylindrical magnetron assembly with a central target cathode and an outer anode
Implementation Method 2
generating a low pressure plasma in the cylindrical anode to sputter out an antimicrobial material from the target cylindrical cathode
Implementation Method 3
generating magnetic field by said magnetic field coils to increase electron density for sputtering
Data Source
AI summary
A cylindrical magnetron sputtering assembly for coating on a flexible polymeric substrates with an antimicrobial material, said assembly comprising a sputtering setup and a cylindrical magnetron assembly; said cylindrical magnetron assembly being mounted in said sputtering setup: wherein said cylindrical magnetron assembly comprises: at least one cylindrical anode with slots mounted on a top base plate; at least one central target cylindrical cathode positioned at the center of said anode; a mechanical assembly for moving plurality of said flexible polymeric substrates; said mechanical assembly comprising at least one winder, at least one unwinder, plurality of pulleys and plurality of motors; said sputtering setup comprising plurality of magnetic field coils, vacuum chamber and plurality of power supply. Also provided is process for producing antimicrobial coating on flexible polymeric substrates by the cylindrical magnetron sputtering assembly.