Asymmetric Bump Array for Particle Segregation
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Solution Overview
Problem
Conventional microfabricated sieving matrices for particle separation face limitations in accuracy, cost, and susceptibility to clogging due to small feature sizes and high manufacturing complexity, especially when separating particles based on size or mass in microfluidic environments.
Innovation Solution
The design of bump array devices with asymmetrically oriented obstacles in microfluidic channels, where the tilt angle of obstacle arrays allows for different critical particle sizes depending on the direction of fluid flow, enabling improved particle segregation without reducing feature size or increasing manufacturing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If small feature sizes are used in microfabricated sieving matrices to improve particle separation precision, then measurement precision is improved, but manufacturing precision deteriorates and device complexity increases
Solution Approach 1:
The patent applies asymmetry by configuring obstacles with non-uniform gap widths, where gaps adjacent to different obstacles have different widths. This asymmetric gap configuration enables different critical particle sizes for particles passing through different gaps, improving separation precision without requiring uniformly small features across the entire device, thus reducing manufacturing precision requirements
2Measurement precision
If small gap sizes are used between obstacles to improve particle separation resolution, then measurement precision is improved, but reliability deteriorates due to clogging susceptibility
Solution Approach 1:
The patent applies local quality by varying the gap widths between obstacles, creating regions with different gap sizes. Some gaps have larger widths that are less susceptible to clogging, while other gaps maintain smaller widths for higher resolution separation. This local variation in gap quality allows the device to simultaneously achieve good separation resolution and reduced clogging susceptibility
Solution Approach 2:
The asymmetric gap configuration creates a distribution of gap widths where not all gaps are uniformly small. This asymmetry ensures that particles have multiple pathways with varying resistance, reducing the likelihood that all pathways will clog simultaneously, thereby improving reliability while maintaining separation capability
3Measurement precision
If small feature sizes are used in microfabricated matrices to improve particle separation capability, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent implements asymmetry through obstacles with deliberately non-uniform gap widths, where each obstacle may have different gap dimensions on different sides. This asymmetric design provides enhanced particle separation capability through varied critical particle sizes, while the systematic nature of the asymmetric configuration allows for manageable device complexity through standardized obstacle designs
4Reliability
If larger gap sizes are used between obstacles to reduce clogging risks, then reliability is improved, but measurement precision deteriorates
Solution Approach 1:
The patent applies local quality by creating spatial variation in gap widths, where specific gaps have larger dimensions for clogging resistance while other gaps maintain smaller dimensions for separation precision. This local differentiation allows different regions of the device to optimize for different functions, achieving both reliability and measurement precision simultaneously
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 enhances particle separation efficiency by altering the fluid flow profile asymmetry, reducing clogging risks, and allowing for larger gap sizes, thereby increasing throughput and reducing operational challenges while maintaining effective separation capabilities.
Implementation Method 1
At the level of flow between two adjacent obstacles under conditions of relatively low Reynold's number, fluid flow generally occurs in a laminar fashion.
Implementation Method 2
separation of particles based on their flow behavior in a fluid-filled field of obstacles in which advective transport of particles by a moving fluid overwhelms the effects of diffusive particle transport
Implementation Method 3
segregation occurring between particles that follow an 'array direction' that is offset from the direction of bulk fluid flow or from the direction of an applied field
Data Source
Figure 1
Figure 2A~2
Figure 3A
AI summary
The disclosure relates to obstacle array devices (also known as bump array devices) for separating populations of particles by size. Improvements over previous obstacle array devices are realized by causing the fluid velocity profile across gaps between obstacles to be asymmetrical with respect to the plane that bisects the gap and is parallel to the direction of bulk fluid flow. Such asymmetry can be achieved by selecting the shape(s) of the obstacles bounding the gap such that the portions of the obstacles upstream from, downstream from, or bridging the narrowest portion of the gap are asymmetrical with respect to that plane. Improvements are also realized by using obstacles that have sharp edges bounding the gaps. Other improvements are realized by selecting obstacle shapes such that the critical particle dimensions defined by the gaps in two different fluid flow directions differ.