Self-Adjusting Microfluidic Channel Structure for Low-Volume Flow
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Solution Overview
Problem
Current microfluidic chip fabrication methods face challenges such as leakage due to small gaps, high capillary forces, and the need for precise mechanical and thermal stability, leading to costly production and inconsistent channel heights affecting sample volume, flow rate, and reaction time.
Innovation Solution
A microfluidic chip with a self-adjusting microchannel height using a flexible film liquid-guiding track on a substrate, where the channel height is determined by the thickness and flatness of the film, allowing for consistent channel dimensions without precise bonding, and utilizing capillary forces for fluid flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multi-layer bonding is used to form sealed microchannels, then channel sealing is improved, but manufacturing precision and cost are worsened due to the need for micron-scale precision and high mechanical/thermal stability
Solution Approach 1:
The invention extracts the bonding operation entirely from the microchannel formation process. Instead of bonding multiple layers to create sealed channels, the patent uses a single-layer flexible film placed on a substrate where the film's own elasticity and surface tension provide the sealing function, eliminating the need for precise multi-layer bonding interfaces
Solution Approach 2:
The invention employs a flexible film as the primary structural element that combines both channel formation and sealing functions. The film's flexibility allows it to conform to the substrate and maintain sealing through elastic deformation rather than requiring precision bonding, directly resolving the contradiction between sealing reliability and manufacturing precision
2Reliability
If smaller gaps are used at bonding interfaces to prevent leakage, then sealing is improved, but capillary forces increase and exceed the intended channel capillary force, causing leakage
Solution Approach 1:
The invention removes the bonding interface from the system entirely, eliminating the source of excessive capillary forces that occur in narrow bonded gaps. The sealing function is achieved through the flexible film's contact with the substrate without creating narrow bonded interfaces that generate problematic capillary suction
Solution Approach 2:
The flexible film creates a sealing interface that does not form narrow bonded gaps. Instead of rigid bonding interfaces that create high capillary forces, the flexible film maintains sealing through elastic contact, allowing the channel to function with appropriate capillary forces for fluid transport
3Manufacturing precision
If adhesive thickness is reduced to achieve micron-scale channel precision, then channel height precision is improved, but mechanical and thermal stability requirements increase, raising manufacturing cost
Solution Approach 1:
The invention extracts the adhesive layer from the microchannel structure, eliminating the trade-off between adhesive thickness and channel height precision. The flexible film itself, through its elasticity and surface properties, provides both the structural definition and sealing function without requiring thin adhesive layers that demand high mechanical and thermal stability
Solution Approach 2:
The flexible film replaces the adhesive layer and provides structural stability through its material properties rather than requiring thin bonding. This eliminates the need for micron-scale adhesive thickness control and the associated high mechanical and thermal stability requirements, reducing manufacturing complexity and cost
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 chip achieves cost-effective manufacturing with low precision requirements, supports smooth flow of various samples, including whole blood, and reduces sample volume needs, enhancing detection capabilities for trace samples.
Implementation Method 1
utilizing capillary forces for fluid flow
Data Source
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AI summary
The present invention belongs to the field of in-vitro diagnostics and immunoassays, and particularly relates to a microfluidic chip with self-adjusting channel height. It comprises a substrate, liquid-guiding track, and top pressing column. The liquid-guiding track is made of a strip of flexible film which is placed on the upper surface of the substrate, and the natural gap between liquid-guiding track and the substrate forms a microchannel. One end of the track is designated as the terminal end, and the other end is the starting end which serves as the sample entrance. Between the track and the substrate, a labeling zone is located near the starting end, and a detection zone is set in the middle section of the track. The microchannel is open to atmosphere along both sides of its width, the channel height can self-adjust as liquid enters. The structure also includes a casing attached circumferentially to the substrate. The guiding track can be manufactured from rolled plastic film, the substrate from prefabricated plastic sheets, and the casing using standard injection molding processes. This avoids the need for precision machining, keeping costs low. The microchannel height is small, requiring only minimal sample volume, and adjusts automatically based on different sample properties, ensuring smooth fluid flow and broad applicability.