Rotating Substrate Flow Path Depth for Centrifugal Liquid Transfer
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Solution Overview
Problem
Existing micro Total Analysis Systems (μ-TAS) face challenges in transferring liquids stepwise through miniature flow paths due to limitations in flow path design, such as varying widths and depths, which affect capillary and centrifugal forces, and issues with biological samples like blood being viscous and adhesive, leading to blockages.
Innovation Solution
A substrate with flow path parts that include chambers and flow paths where the imaginary chamber length is adjusted based on distance from the axis of rotation, allowing for stepwise liquid transfer without varying cross-sectional areas, and using hydrophobic materials to prevent adhesion and ensure smooth flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the width of flow paths is varied according to position from center of rotation to generate sufficient capillary force, then liquid transfer is enabled, but the manufacturing process becomes complex and difficult to control
Solution Approach 1:
The patent applies local quality by varying the depth of flow paths at different radial positions from the center of rotation. Flow paths closer to the center have greater depth, while those farther away have lesser depth, creating localized property changes that generate appropriate capillary forces at each position without requiring complex width variations
Solution Approach 2:
The patent changes the depth parameter of flow paths as a function of radial position to control capillary force. By establishing a specific relationship between depth and radial distance, the system achieves controlled liquid transfer while maintaining manufacturing simplicity through standard photolithography processes
2Reliability
If the depth of flow paths is reduced to increase capillary force, then liquid transfer is improved, but the flow path cross-sectional area decreases and manufacturing precision requirements increase
Solution Approach 1:
The patent systematically varies the depth parameter across different radial positions to optimize capillary force generation. This parameter change approach allows deeper flow paths closer to the center and shallower paths at the periphery, achieving the desired capillary force distribution while maintaining manufacturability through controlled depth variation rather than extreme cross-sectional reductions
3Productivity
If centrifugal force is used for liquid transfer in miniature flow paths, then dead volume is eliminated and parallel processing is enabled, but the system becomes sensitive to viscous and adhesive properties of biological samples
Solution Approach 1:
The patent adjusts the depth parameter of flow paths to compensate for the effects of viscosity and adhesion in biological samples. By optimizing the depth at each radial position, the system maintains appropriate capillary forces that work in conjunction with centrifugal force, ensuring reliable transfer of viscous biological samples while preserving the efficiency benefits of centrifugal processing
Solution Approach 2:
The patent implements local quality variations in flow path depth to address the specific challenges of transferring biological samples. Each flow path segment has depth optimized for its radial position, creating localized capillary forces that help overcome adhesion and viscosity effects during centrifugal transfer
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
Enables efficient stepwise liquid transfer according to rotation speed, reduces the volume of solution subjected to centrifugal force, and ensures reliable transfer of biological samples by controlling centrifugal and capillary forces, while simplifying the manufacturing process.
Implementation Method 1
a substrate that is rotatable around an axis of rotation... By this means, a micro-flow path that is more distant from the axis of rotation generates greater capillary force. Liquid in the miniature chambers, the liquid transfer of which is prevented by the capillary force produced in the micro-flow paths, is transferred to the neighboring microchambers in the direction of centrifugal force by the centrifugal force produced by the rotation of the substrate.
Implementation Method 2
micro-flow paths that are more distant from the center of rotation have a narrower width... a micro-flow path that is more distant from the axis of rotation generates greater capillary force. Liquid in the miniature chambers, the liquid transfer of which is prevented by the capillary force produced in the micro-flow paths
Data Source
AI summary
A substrate including a channel part having a chamber in which a liquid can be fed stepwise from a chamber to another chamber at the channel part formed in the substrate, depending on the rotational speed of the substrate. A first chamber, a second chamber, a third chamber, and a channel interconnecting them are formed at the channel part formed in the substrate. Furthermore, the width and/or the depth of the first chamber is set smaller than the width and/or the depth of the second chamber. Consequently, the volume of solution subjected to centrifugal force in the first chamber is larger than the volume of solution subjected to centrifugal force in the second chamber.