EHD Patterning of Liquid Polymer Films
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Solution Overview
Problem
Current methods for producing micro-scale patterned polymer films are limited in their ability to create arbitrarily varying patterns in large areas and are not commercially viable for producing industrially relevant quantities, as they rely on master-based techniques and are sensitive to external forces, restricting their scalability and efficiency.
Innovation Solution
The implementation of Electrohydrodynamic (EHD) patterning techniques using two curved conveyors with an electric field to create micro-scale patterned structures in a polymer film, allowing for continuous and economical production of digital micro-scale polymer structures, with options for nanostructure alignment and discreet pattern formation, facilitated by dynamic charge generation and curing mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If master-based methods (rolling mask lithography, Nanoimprint Lithography, Holographic Lithography) are used to create patterned thin films, then micro-scale patterns can be formed with controlled topology, but the methods cannot create arbitrarily varying patterns in large area format or in a dynamic and digital manner
Solution Approach 1:
The patent replaces master-based mechanical patterning methods with electrohydrodynamic (EHD) patterning that uses electric fields to directly shape liquid polymer films. This substitution enables digital and dynamic pattern creation without physical masks or stamps, allowing arbitrary pattern variation while maintaining large-area production capability through continuous film processing
Solution Approach 2:
The patent utilizes changes in electric field parameters (voltage, duration, spatial distribution) to dynamically control pattern formation in liquid polymer films. By varying these electrical parameters, arbitrarily varying patterns can be created in real-time during continuous production, achieving both adaptability and productivity
2Manufacturing precision
If conventional EHD patterning techniques are used with templates, then micro- or nano-structures can be transferred onto thin polymer films, but the height of replication is limited at the nano-scale because the electric field is sensitive to the spacer height of the template
Solution Approach 1:
The patent extracts and eliminates the template component from conventional EHD patterning. By removing the template and its associated spacer height requirements, the method achieves nano-scale replication without the sensitivity to spacer dimensions that limited previous approaches
Solution Approach 2:
The patent introduces a charged roller as an intermediary element that generates the electric field directly within the liquid polymer film without requiring a template. This intermediary approach enables precise electric field control and pattern formation while avoiding the mechanical constraints of template-based systems
3Adaptability or versatility
If EHD patterning is applied to create micro-scale patterns in liquid polymer films, then digital and dynamic pattern creation is enabled, but the methods are not commercially viable because they are unable to produce commercially useful quantities of film
Solution Approach 1:
The patent implements continuous EHD patterning of liquid polymer films as they are conveyed through the system. This continuous action, rather than batch processing, enables commercially useful production quantities while maintaining digital pattern creation capability through real-time electric field control
Solution Approach 2:
The patent applies EHD patterning to liquid polymer films before they are cured and solidified. This preliminary patterning of the liquid state allows for easier manipulation and continuous processing, enabling commercial production volumes while maintaining digital flexibility in pattern design
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
This method enables the efficient and cost-effective production of micro-scale patterned structures that can be used in various commercial applications, including flexible electronics and drug delivery, with high production output and flexibility in pattern creation.
Implementation Method 1
Electrohydrodynamic (EHD) patterning is a recently developed technology that involves electrically transferring the micro- or nano-structures formed on a template onto a thin polymer film by shaping the surface of the liquid polymer film through a balance of applied forces on the liquid and the surface tension of the liquid
Implementation Method 2
shaping the surface of the liquid polymer film through a balance of applied forces on the liquid and the surface tension of the liquid
Implementation Method 3
The present invention focuses on EHD patterning techniques applied to polymer thin films having a height/thickness that is much less than the length-scale of the instability, so the kinetics of the polymer thin film are completely described by lubrication theory, and the emerging pattern is driven by the fastest growing capillary wave mode
Implementation Method 4
An appropriate curing mechanism (e.g., a UV laser or thermal treatment) is utilized to cross-link (cure) the polymer thin film while undergoing EHD patterning
Data Source
AI summary
A liquid thin film is disposed on a conveyor surface (e.g., a roller or belt) that moves the thin film into a precisely controlled gap (or nip) region in which the liquid thin film is subjected to an electric field that causes the liquid to undergo Electrohydrodynamic (EHD) patterning deformation, whereby portions of the liquid thin film form patterned liquid features having a micro-scale patterned shape. A curing mechanism (e.g., a UV laser) is used to solidify (e.g., in the case of polymer thin films, crosslink) the patterned liquid inside or immediately after exiting the gap region. The patterned structures are either connected by an intervening web as part of a polymer sheet, or separated into discreet micro-scale structures. Nanostructures (e.g., nanotubes or nanowires) disposed in the polymer become vertically oriented during the EHD patterning process. Segmented electrodes and patterned charges are utilized to provide digital patterning control.