Coextruded Thermoplastic Films for Microfluidic Device Manufacturing
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Solution Overview
Problem
Microfluidic devices face challenges in maintaining accurate microscale fluid containment features and structural integrity during manufacturing, which can lead to deformation and impaired performance, especially when using thermoforming processes, and require materials with optical clarity and biocompatibility for commercial viability.
Innovation Solution
The use of coextruded thermoplastic polymeric films with higher and lower softening temperature materials, including cyclic olefin copolymers and polyethylene, to create microfluidic devices with structural integrity and uniform internal surfaces, along with optional layers for support, gas barrier, and liquid barrier functions, ensuring stability and optical clarity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If thermoforming processes are used to manufacture microfluidic devices, then productivity and ease of manufacture are improved, but manufacturing precision deteriorates due to deformation of microstructures
Solution Approach 1:
The device is divided into multiple layers with different functions: a support layer for structural integrity, a fluid containment layer for microstructure formation, and seal layers for bonding. This segmentation allows each layer to be optimized independently, enabling thermoforming of the support layer without deforming the delicate fluid containment microstructures.
Solution Approach 2:
Different regions of the device have different material properties and thicknesses. The support layer has higher thickness and thermal stability for withstanding thermoforming, while the fluid containment layer has lower thickness for maintaining microstructure precision. This local differentiation resolves the contradiction between overall structural strength and local microstructure accuracy.
2Device complexity
If single-layer structures are used, then device complexity is reduced, but structural integrity and functional performance deteriorate
Solution Approach 1:
Multiple layers with different functions are combined into a single integrated device structure. The support layer provides mechanical strength, the fluid containment layer provides microstructure definition, and the seal layers provide bonding capability. This merging of functions into a multi-layer structure achieves both structural integrity and functional performance.
Solution Approach 2:
The device uses composite construction with different polymeric materials optimized for different functions. The support layer uses materials with high thermal and mechanical stability for structural integrity, while the fluid containment layer uses materials with good optical properties and chemical resistance. This composite approach resolves the contradiction between simplicity and reliability.
3Measurement precision
If optical clarity is prioritized for fluorescence detection, then detection sensitivity is improved, but material selection becomes more restrictive
Solution Approach 1:
Different layers have different material requirements optimized for their specific functions. The fluid containment layer uses optically clear materials for fluorescence detection, while the support layer uses materials optimized for thermal and mechanical stability. This local optimization allows each layer to use the most suitable material for its function, resolving the contradiction between optical performance and material versatility.
4Manufacturing precision
If film thickness is reduced for better microstructure definition, then manufacturing precision is improved, but structural integrity deteriorates
Solution Approach 1:
The device structure is segmented into a thick support layer for mechanical strength and a thin fluid containment layer for microstructure precision. This segmentation allows the thin film to maintain accurate microstructure definition while the thick support layer provides the necessary structural integrity and handling strength.
Solution Approach 2:
The film thickness varies by region and function: the support layer has greater thickness for structural strength, while the fluid containment layer has lesser thickness for microstructure precision. This local differentiation in thickness resolves the contradiction between overall strength and local precision.
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 allows for the creation of microfluidic devices with precise microstructures and enhanced stability, enabling accurate mass production and maintaining optical clarity, while preventing deformation and ensuring biocompatibility for applications like DNA analysis and PCR reactions.
Implementation Method 1
heating said first and second films to a temperature sufficient to melt said relatively lower melt temperature material of said first film and said relatively lower melt temperature material of said second film thereby joining said films together
Implementation Method 2
WO 94/26414 discloses a method for fabricating a microfluidic device using a heatsealing process whereby a laminate with a lower melting point layer is brought into contact with another laminate and the two laminates are heated to fuse the heatseal layers
Data Source
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AI summary
The present invention relates to a microfluidic device, comprising a laminate of first and second films, one or each film including an integrally thermoformed structure such that the films together define an enclosed volume (19) for fluid containment therebetween, characterised in that each film itself comprises a laminate of a relatively higher softening temperature thermoplastic polymeric material (14,17) and with respect thereto, a relatively lower melt temperature thermoplastic polymeric material (15,16), the respective relatively low melt temperature thermoplastic polymeric materials of each film being melted together to attach the said first and second films together. The invention further relates to a method of manufacturing the microfluidic device.