Coaxial Microfluidic Jetting for Precision Deposition
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Solution Overview
Problem
Existing microfluidic jetting technologies face challenges with clogging in small nozzles and instability in delivering ink at high precision, particularly for nozzle diameters less than 50 microns, due to issues like trapped bubbles and solid particles, which limits the practical deposition rate and accuracy in direct printing applications.
Innovation Solution
The use of a multi-component coaxial jetting method where one or more inner liquids are propelled by an outer sheath flow through a larger diameter nozzle, stabilizing the deposition process and reducing clogging by forming an annular liquid jet with limited contact time, allowing for stable jetting and precise printing of sub-micron filaments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single-component liquid jet is used with small nozzle diameter (<50 microns), then deposition precision is improved, but clogging occurs due to trapped bubbles and solid particles
Solution Approach 1:
The liquid jet is segmented into multiple components with separate flow paths. The inner component flows through a small inner nozzle for precision, while the outer component flows through a larger outer nozzle for reliability. This segmentation allows each component to serve its specific function without compromising the other.
Solution Approach 2:
The outer liquid component acts as an intermediary that protects the inner liquid component from direct contact with the environment and potential contaminants. The outer nozzle serves as a mediator that provides a larger aperture for stable flow while the inner nozzle maintains precise deposition capability.
2Manufacturing precision
If nozzle diameter is reduced to increase precision, then edge definition is improved, but deposition rate decreases due to limited ink delivery
Solution Approach 1:
The deposition system is segmented into inner and outer liquid components that can be deposited simultaneously through separate nozzles. This allows the inner component to provide precise edge definition while the outer component contributes to overall material deposition, effectively increasing total productivity without sacrificing precision.
Solution Approach 2:
The inner and outer liquid components are merged into a single coaxial jet structure that deposits both materials simultaneously in one operation. This combining of multiple deposition functions into a unified process increases the overall deposition rate while maintaining the precision benefits of the small inner nozzle.
3Reliability
If multi-component coaxial jetting is used to reduce clogging, then reliability is improved, but device complexity increases
Solution Approach 1:
The nozzle structure is designed with a nested configuration where the inner nozzle is positioned within the outer nozzle. This nesting arrangement allows both nozzles to be integrated into a single compact component, reducing overall device complexity while maintaining the reliability benefits of multi-component jetting.
Solution Approach 2:
The coaxial nozzle structure serves multiple functions simultaneously: the inner nozzle provides precise material delivery, the outer nozzle provides stable flow and protection, and together they form an integrated deposition system. This multi-functionality reduces the need for separate components and simplifies the overall device architecture.
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 approach enables stable and precise direct printing of multi-component traces with sub-micron edge definition, reducing clogging issues and achieving continuous line deposition on moving substrates with improved deposition rates and accuracy, even at smaller nozzle diameters, by leveraging the ratio of core and sheath flow rates to control the filament diameter and breakup distance.
Implementation Method 1
In hydrodynamic focusing, an annular distribution of a core liquid and a sheath liquid is forced through a channel or nozzle, with the core liquid being stretched into a thin filament as the liquids accelerate through the constriction.
Implementation Method 2
The core liquid is stretched into a filament with a width as small as 1 micron. The width of the core filament is a function of the ratio of the core and sheath flow rates.
Implementation Method 3
This approach enables stable and precise direct printing of multi-component traces with sub-micron edge definition, reducing clogging issues and achieving continuous line deposition on moving substrates
Data Source
AI summary
The object of the invention is the provision of methods for controlled production of continuous multi-component filaments or discreet structures using a multi-component liquid jet issuing from an orifice. A multi-component jet consists of two or more liquids. The liquids may be miscible or immiscible, and form a co-axially propagating flow along the central axis of a flow cell. The working distance between the exit orifice and a substrate can be as large as 50 mm, so that in-flight processing of the jet is possible. The coaxial flow consists of an outer sheath liquid and an inner sample liquid or composite of liquids. The flow cell and the exit channel of the deposition head are heated so that the pressurized sheath liquid temperature is raised to near or above the boiling point of the sheath liquid at the local atmospheric pressure. The jet exits the deposition head through the orifice, and the outer liquid is evaporated as the jet falls at atmospheric pressure. The sheath liquid is processed thermally, optically, or chemically during flight to form a protective or insulating layer for the inner liquid or liquids. The inner liquids may contrastingly consist of an ultraviolet (UV) curable ink that is processed in-flight or after deposition. Since UV curable inks contain no volatile components, the coaxial jetted filament can be processed without producing cracks or bubbles in the sheath layer. Line widths are produced in the range from approximately 1 to 1000 microns.