Wax Patterning for Microfluidic Analysis Membranes
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Solution Overview
Problem
Existing methods for manufacturing microfluidic devices with porous analysis membranes are limited by high production costs, inefficiency in using photosensitive resins, and inability to handle thick porous substrates, leading to suboptimal pattern complexity and impermeability in hydrophilic zone creation.
Innovation Solution
A method involving affixing wax patterns on both sides of a porous substrate, subjecting it to heat and mechanical compression to allow wax impregnation, and then relaxing the substrate to form impermeable borders delimiting hydrophilic zones, enabling the use of substrates up to 1000 μm thick and reducing production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If photolithography method is used to create hydrophilic zones with impermeable borders, then pattern precision can be achieved, but production cost increases significantly due to high resin consumption
Solution Approach 1:
The patent extracts and removes the photosensitive resin from the process entirely, replacing it with a wax-based system. The wax is applied as a paste or suspension that can be easily removed after serving its purpose of defining the pattern, eliminating resin consumption while maintaining pattern precision through the wax's ability to form impermeable borders in the porous substrate
Solution Approach 2:
The patent uses a disposable wax application method where wax is applied to define patterns, serves its function of creating impermeable borders, and then can be removed or left behind as a temporary structure. This replaces the expensive photosensitive resin with a cheap, consumable material that achieves the same patterning function without the high cost
2Length of stationary object
If conventional methods are used for creating patterns, then thin substrates can be processed, but thick porous substrates (up to 1000 μm) cannot be effectively handled
Solution Approach 1:
The patent applies preliminary action by first saturating the thick porous substrate with liquid wax or paste before drying. This pre-impregnation ensures that the wax penetrates deeply into the thick substrate (up to 1000 μm) before the drying process sets the pattern. The preliminary saturation step allows the wax to distribute uniformly throughout the thickness, enabling effective patterning of thick substrates that conventional methods cannot handle
Solution Approach 2:
The patent changes the physical parameters of the wax application - using a liquid paste or suspension form rather than solid wax, and controlling the viscosity and concentration to ensure proper penetration into thick substrates. The drying process parameters are also optimized to ensure complete impregnation of thick materials while maintaining pattern fidelity
3Ease of manufacture
If wax is applied to create impermeable borders, then production cost is reduced, but the impermeability and fineness of borders may be compromised
Solution Approach 1:
The patent applies partial or excessive action by using multiple layers of wax or applying wax with higher concentration than minimum required. This ensures that the wax forms sufficiently thick and impermeable borders within the substrate, compensating for any potential gaps or insufficient penetration. The excessive wax application guarantees reliable impermeability while still maintaining cost advantages over photolithography
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 allows for the production of microfluidic devices with impermeable wax borders of high fineness and impermeability, suitable for a wide range of porous substrates, including fiberglass, enabling efficient plasma analysis from whole blood and reducing the need for additional filtration systems.
Implementation Method 1
a sheet of porous substrate, impregnated with liquid wax in its thickness
Implementation Method 2
subjecting it to heat treatment capable of causing at least partial solidification of the wax
Implementation Method 3
subjecting it to mechanical treatment capable of momentarily compressing the thickness of all or part of said substrate sheet
Implementation Method 4
said sheet of substrate is subjected to a phase of mechanical and thermal relaxation, capable of allowing said sheet of substrate to regain at least part of its initial thickness
Data Source
Figure 1~2
Figure 3~4(B)
Figure 5~6
AI summary
The invention relates to a method for manufacturing an analysis membrane (10) of a microfluidic device; said analysis membrane being formed from a sheet of porous substrate (11) in the thickness of which solid wax forms impermeable borders (12) delimiting hydrophilic zones (13) and describing, through said sheet of substrate (11), a pattern traced in wax; characterized in that it comprises the following steps: - an intermediate pattern (12a, 12b), shaped in wax in the image of said pattern traced in wax which will be formed by the impermeable borders of the analysis membrane (11), is affixed to each of the faces of a sheet of porous substrate (11) so that, on either side of the thickness of said sheet of substrate (11), said intermediate patterns (12a, 12b), mutually symmetrical, are positioned at least substantially opposite each other;- maintained at least substantially horizontally, said substrate sheet (11) is subjected to a heat treatment capable of causing at least partial melting of the wax constituting the intermediate patterns (12a, 12b) affixed to the faces of said substrate sheet (11), and to a mechanical treatment capable of compressing the thickness of all or part of said substrate sheet (11); - said substrate sheet (11) is subjected to a mechanical and thermal relaxation phase capable of allowing said substrate sheet (11) to at least partially regain its initial thickness and the wax to resolidify within the thickness of said substrate sheet (11); and in that the thickness of said substrate sheet (11) is between 200 µm and 1000 µm;