Direct Imaging Microfluidic Device Fabrication
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Solution Overview
Problem
Conventional microfluidic devices require the fabrication of a mold or master for soft lithography, which is time-consuming, costly, and limits feature size and complexity, making high-volume production and customization of microstructures challenging.
Innovation Solution
A direct imaging method using a photosensitive composition comprising a binder, monomer, and photoinitiator, where the photopolymerizable layer is imagewise exposed to actinic radiation through a mask to create microstructures without the need for a mold, allowing for the formation of microfluidic devices with varying channel sizes and shapes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional soft lithography is used to fabricate microfluidic devices, then microstructures can be formed, but the process requires time-consuming and costly mold fabrication that limits high-volume production and customization
Solution Approach 1:
The patent extracts and eliminates the mold fabrication step from the conventional soft lithography process. By using direct photolithographic patterning on PDMS followed by plasma treatment and molding, the method removes the time-consuming intermediate mold creation step while maintaining the ability to produce microfluidic devices at high volume.
Solution Approach 2:
The patent performs preliminary patterning of the PDMS substrate using photolithography before the molding step. This preliminary action creates the microstructure pattern directly in the PDMS, eliminating the need for separate mold fabrication and enabling rapid production of customized microfluidic devices.
2Productivity
If conventional soft lithography with molds is used, then microstructures can be replicated, but the process becomes costly and complex for high-volume production
Solution Approach 1:
The patent merges the patterning and molding steps into a single integrated process. By combining photolithographic patterning of PDMS with subsequent plasma treatment and molding in sequence, the method simplifies the overall fabrication process while maintaining high-volume production capability and reducing process complexity.
3Manufacturing precision
If photolithography and etching on hard materials like silicon and glass are used, then microfluidic devices can be fabricated, but the process is costly, labor intensive, and requires clean-room conditions
Solution Approach 1:
The patent replaces the mechanical and chemical etching processes used on hard materials with photolithographic patterning followed by plasma treatment and molding on soft PDMS material. This substitution maintains manufacturing precision for microstructures while dramatically simplifying the fabrication process and eliminating the need for clean-room conditions.
Solution Approach 2:
The patent changes the material parameter from hard materials (silicon, glass) to soft elastomeric material (PDMS), and changes the processing method from photolithography-etching to photolithography-plasma treatment-molding. This parameter change maintains microstructure precision while greatly improving ease of manufacture and eliminating clean-room requirements.
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
Enables the economical and high-volume production of microfluidic devices with complex microstructures, facilitating degas-driven flow and versatile fluid control, suitable for point-of-use diagnostics and other applications.
Implementation Method 1
a photopolymerizable layer is imagewise exposed to actinic radiation through a mask to create microstructures without the need for a mold
Data Source
Figure 1A~1D
Figure 1E~1H
Figure 2A
AI summary
A microfluidic device is formed from a cover member and a microfluidic precursor that is prepared from a photosensitive element. The photosensitive element is a solid layer of a photopolymerizable composition that includes at least a binder, a monomer, and a photoinitiator. A method for forming the microfluidic device from the photosensitive element includes imagewise exposing the photopolymerizable layer to actinic radiation through a mask and treating to form a relief surface having microstructures or features, such as one or more channels and one or more chambers, that are suitable for use in the microfluidic device. The method provides microstructures that can be formed to have different dimensions that provide particular advantages for a microfluidic device that is operated by degas-driven flow to transport a fluid through the microstructures.