Microfluidic Device Welding via Compressed Elastomer Film
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Solution Overview
Problem
Conventional microfluidic device welding methods often result in capillary formation between substrates, which is problematic for many microfluidic applications, especially when the weld seam is formed at a distance from the microchannels, leading to deformation and volume changes in the microchannel walls.
Innovation Solution
A method involving a thermoplastic elastomer film sandwiched between a base substrate and a cover substrate, where the film is compressed to reduce thickness, and then laser-welded, fixing the substrates at a distance that prevents the elastomer from expanding back to its original thickness, thus avoiding capillary formation by acting as a sealant.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the weld seam is formed at a distance from the microchannel, then capillary formation is avoided, but the weld seam cannot be positioned exactly flush along the indentation opening and the indentation volume may change
Solution Approach 1:
A thermoplastic elastomer film is introduced as an intermediary component between the two substrates. This film is compressed during assembly to reduce its thickness, and laser welding is performed through this compressed film at a distance from the microchannel opening. The elastomer film acts as a mediator that enables welding at the required distance while maintaining seal integrity and preventing capillary formation, thus resolving the contradiction between weld positioning accuracy and capillary prevention.
2Manufacturing precision
If the weld seam runs directly along the indentation opening, then positioning accuracy is improved, but capillaries form between substrates and mask layer
Solution Approach 1:
The thermoplastic elastomer film serves as an intermediary that allows the weld seam to be positioned at a distance from the indentation opening while maintaining effective sealing. By compressing the elastomer film during assembly, the welding can be performed through this intermediate layer at the optimal distance, preventing capillary formation between the substrates and mask layer while achieving the required positioning accuracy.
Solution Approach 2:
The thickness of the elastomer film is dynamically changed by applying compression force during assembly. The film is compressed to reduce its thickness to a specific range (≥2 μm to ≤100 μm), which enables laser welding at the appropriate distance from the microchannel opening. This parameter change in film thickness allows the weld seam to be positioned optimally to prevent capillary formation while maintaining manufacturing precision.
3Reliability
If pressing pressure is applied to compress the elastomer film, then seal quality is improved, but the film thickness is reduced which may affect device assembly
Solution Approach 1:
The elastomer film is compressed to reduce its thickness before the laser welding process is performed. This preliminary compression action prepares the film in its thinnest state, ensuring optimal seal quality and enabling welding at the correct distance from the microchannel opening. The compression is maintained during welding, and the weld is formed while the film is in this compressed, thinnest configuration, thus achieving both high seal quality and proper welding positioning.
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 effectively prevents capillary formation between substrates while allowing for precise control of the weld distance from the indentation opening, avoiding deformation and volume changes in the microchannel walls, thereby enhancing the reliability of microfluidic devices.
Implementation Method 1
subjecting the arrangement to a pressure such that the elastomeric film is compressed between the base substrate and the cover substrate while reducing the thickness of the elastomeric film
Implementation Method 2
When the pressing pressure is removed in process step d), the elastomeric film tends to expand and resume the original thickness from process step a). However, the weld point fixes the base substrate and the cover substrate at a distance from one another which essentially corresponds to the reduced film thickness from method step b), so that the elastomeric film cannot expand to its original thickness.
Implementation Method 3
forming at least one, the thermoplastic elastomeric film, the base substrate and the cover substrate connecting weld point by laser welding
Implementation Method 4
welded to another thermoplastic component by the action of a laser beam
Data Source
Figure 1a~1c
Figure 1d~2b
AI summary
The present invention relates to a method for producing a microfluidic device, comprising the following method steps: a) arranging a thermoplastic elastomeric film (1) between a base substrate (2) and a cover substrate (3), wherein at least one of the substrates (2, 3) has at least one depression (4, 5) for forming a microfluidic chamber having a depression opening (4a, 5a) on the side (2a, 3a) of the substrate (2, 3) facing the elastomeric film (1), b) applying pressing power to the arrangement such that the elastomeric film (1) is compressed between the base substrate (2) and the cover substrate (3), in which process the thickness (d0) of the elastomeric film (1) is reduced, c) forming, by means of laser beam welding, at least one weld joining the thermoplastic elastomeric film (1), the base substrate (2) and the cover substrate (3), and d) removing the pressing power, in order to prevent the formation of capillaries between the base substrate (2) and the cover substrate (3).