Microfluidic Laser Welding for Fluid-Tight Seals
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Solution Overview
Problem
Conventional microfluidic devices face challenges in achieving fluid-tight seals around external access points, leading to potential liquid leakage or pressure loss, which are often addressed using O-rings or gaskets that require complex alignment and testing.
Innovation Solution
The use of a ring-shaped continuous seam weld formed by an optical welding process, specifically using a laser beam to melt and bond the substrates around through holes, creating a fluid-tight seal without the need for additional gaskets, and allowing for bonding of chemically dissimilar materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If O-rings or gaskets are used to seal around through holes, then fluid-tight sealing is achieved, but device complexity increases and alignment precision becomes more difficult
Solution Approach 1:
The patent removes the separate seal components (O-rings, gaskets) from the device structure entirely. Instead, the seal function is integrated directly into the substrate through laser-welded seals that form fluid-tight barriers around through holes without requiring additional sealing elements.
Solution Approach 2:
The patent combines the sealing function with the substrate structure itself. The laser-welded seal merges the sealant material with the substrate material to form an integrated sealing structure, eliminating the need for separate seal components and simplifying the overall device architecture.
2Reliability
If O-rings or gaskets are used to seal around through holes, then fluid-tight sealing is achieved, but manufacturing precision requirements increase
Solution Approach 1:
The patent replaces the mechanical seal system (O-rings, gaskets requiring physical installation and alignment) with a laser welding system. The laser-welded seal is formed by melting and fusing material in a controlled manner, eliminating the need for mechanical alignment and installation of separate seal components.
Solution Approach 2:
The patent changes the sealing mechanism from mechanical contact and deformation (O-rings compressing against surfaces) to thermal processing (laser welding). This parameter change allows for more precise control of the seal formation process and reduces sensitivity to alignment variations.
3Reliability
If conventional sealing methods are used, then sealing is achieved, but leak testing becomes necessary and time-consuming
Solution Approach 1:
The patent incorporates real-time monitoring during the laser welding process to ensure seal quality. The system provides feedback on welding parameters and seal formation, allowing for immediate detection and correction of potential defects without requiring separate leak testing procedures.
4Strength
If laser welding is used to bond substrates, then bonding strength is improved, but the substrates must be transparent to the laser wavelength
Solution Approach 1:
The patent introduces a sealant material as an intermediary that is deposited around the through holes and then laser-welded to form seals. This sealant layer acts as a mediator that can be effectively bonded by laser welding while allowing the use of various substrate materials with different optical properties.
Solution Approach 2:
The patent employs composite material structures where a sealant layer is combined with substrate materials. This composite approach allows the sealant to provide the laser-weldable interface while the substrates can be made from various materials including those that are not transparent to the laser wavelength, thus expanding material compatibility.
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
The laser weld provides a stable, long-lasting seal that prevents leakage and pressure loss, is optically inspectable for quality assurance, and can bond layers made of different polymers, eliminating the need for costly and contaminating leak testing.
Implementation Method 1
a ring-shaped continuous seam weld formed by an optical welding process, specifically using a laser beam to melt and bond the substrates around through holes
Implementation Method 2
using a laser beam to melt and bond the substrates
Data Source
Figure 1
Figure 2A~2B
Figure 3~5B
AI summary
A microfluidic device comprising in sequence first, second and third layers of plastics materials. A microfluidic circuit including a laterally extending microfluidic channel is formed at the interface between the first and second layers by surface structure in one or both of the first and second layers. A via is formed in the third layer for supplying or removing fluid to or from the microfluidic circuit. A conduit is formed in the second layer to provide fluid communication between the microfluidic channel and the via. A weld is formed at the interface between the second and third layers in a continuous closed path around the via and forms a fluid-tight seal for fluid flow between the via and the microfluidic circuit.