Lateral-flow assay concave filter meniscus control
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Solution Overview
Problem
Existing lateral-flow assay devices face challenges in achieving efficient plasma yield and sensitivity, especially when using smaller sample volumes, due to issues with fluid flow and filtration.
Innovation Solution
The use of a concave-shaped filter over the sample addition zone, supported peripherally by a cover, creates a fluid meniscus retained by capillary pressure. The geometry of the filter, including the angle subtended between the filter and the substrate, controls the meniscus size and filtration rate, optimizing plasma yield and flow characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a porous material is used in the sample addition zone to absorb liquid sample and trap red blood cells, then plasma yield is improved, but filtration flow rate decreases
Solution Approach 1:
The device divides the filtration function into two separate zones: the sample addition zone uses a porous material (first filter) for plasma separation, while the wicking zone uses a different porous material (second filter) for flow control and plasma yield enhancement. This segmentation allows each zone to be optimized for its specific function without compromising the other.
Solution Approach 2:
Different porous materials with specific properties are assigned to different zones based on local requirements. The first filter in the sample addition zone is selected for its plasma separation capability, while the second filter in the wicking zone is selected for its flow control characteristics. This local optimization resolves the contradiction between plasma yield and filtration flow rate.
2Ease of operation
If smaller sample volumes are used to reduce invasiveness, then patient comfort is improved, but sensitivity decreases
Solution Approach 1:
The device changes the physical parameters of the filtration system by using a second porous filter in the wicking zone with specific pore size and material properties. This parameter change enables efficient plasma recovery from smaller sample volumes, maintaining sensitivity while reducing the required sample volume for accurate testing.
3Productivity
If a non-porous substrate with microposts is used to define fluid path, then flow control is improved, but device complexity increases
Solution Approach 1:
The invention replaces the complex non-porous substrate with microposts with porous filter materials that have built-in flow control capabilities. The porous structure of the filters themselves provides the flow control function, eliminating the need for additional micropost structures and simplifying the overall device design while maintaining effective flow management.
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 design enhances the yield of plasma and other fluids of interest, allowing for the use of smaller sample volumes while maintaining sensitivity and reliability, and prevents fluid from becoming trapped, ensuring consistent flow through the assay device.
Implementation Method 1
The geometry of the filter, including the angle subtended between the filter and the substrate, controls the meniscus size and filtration rate
Implementation Method 2
creates a fluid meniscus retained by capillary pressure
Implementation Method 3
a filter supported peripherally within the aperture and configured to permit at least a portion of the sample to pass therethrough as the filtrate
Data Source
AI summary
Described herein are clinical diagnostics and more specifically to a lateral-flow assay devices.