Laminated Filter Elements for Capillary Blood Filtration
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Solution Overview
Problem
Existing filtration systems for biological samples, such as whole blood, face challenges with bulk particulate removal due to clogging and peripheral flows, and require pressurized flows or poor sealing methods, which affect efficiency and repeatability.
Innovation Solution
A lateral flow filtration system with multiple planar filter layers of varying pore sizes, where the top filter has larger pores for initial filtration and the bottom filter has smaller pores, allowing for efficient separation of particles through a capillary channel without external forces, using a cartridge configuration with a filtration chamber and capillary outlet.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If transverse flow filtration is used to remove particulates, then filtration efficiency is improved, but device complexity and sealing requirements increase
Solution Approach 1:
The filter is divided into multiple stacked filter elements with different pore sizes, where the top filter element has larger pores for initial filtration and the bottom filter element has smaller pores for fine filtration. This segmentation allows each layer to handle specific particle sizes, improving overall filtration efficiency while simplifying the sealing requirements compared to a single complex filter system.
Solution Approach 2:
The invention transitions from conventional single-plane filtration to a multi-layer stacked configuration where filtration occurs in the vertical dimension through multiple filter elements. This dimensional change allows simultaneous gross and fine filtration in different layers, enhancing filtration efficiency without requiring complex lateral sealing mechanisms.
2Reliability
If filter thickness is increased to improve separation efficiency, then filtration performance is improved, but device volume increases
Solution Approach 1:
The invention achieves enhanced separation efficiency by stacking multiple filter elements vertically, utilizing the vertical dimension rather than increasing the lateral footprint. This allows the device to maintain a compact volume while providing multiple filtration stages through the stacked configuration of filter elements with different pore sizes.
Solution Approach 2:
Multiple filter elements are nested in a stacked configuration where the top filter element sits above the bottom filter element within a compact housing. This nesting arrangement allows sequential filtration stages to be contained within a small vertical space, improving separation efficiency without significantly increasing device volume.
3Device complexity
If single filter is used for both gross and fine filtration, then device complexity is reduced, but filtration efficiency decreases
Solution Approach 1:
The filtration function is segmented into two distinct filter elements: a top filter element with larger pores for gross particulate removal and a bottom filter element with smaller pores for fine particulate removal. This segmentation of the filtration function into specialized stages improves overall filtration efficiency while maintaining relatively simple device complexity through the stacked modular design.
Solution Approach 2:
Each filter element is designed with local quality appropriate to its function: the top filter has larger pores optimized for gross filtration, while the bottom filter has smaller pores optimized for fine filtration. This local optimization of pore sizes in different regions of the filter stack enhances overall filtration efficiency without requiring a complex single-filter design.
4Reliability
If conventional sealing methods are used, then filter sealing is achieved, but variable absorption of sealing compound into filter occurs
Solution Approach 1:
The invention extracts the sealing function from complex chemical sealing compounds and implements it through simple mechanical means: the stacked filter elements are held together by a housing that provides inherent mechanical sealing through friction and tight fit. This eliminates the need for sealing compounds that would otherwise be absorbed by the filter materials, preventing variable absorption issues while maintaining effective sealing.
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 configuration effectively removes bulk and fine particulates in a thin package, preventing clogging and peripheral flows, enhancing filtration efficiency and flow rates while minimizing filtrate retention and maximizing plasma outflow volume.
Implementation Method 1
A capillary device can include multiple membranes with varying pore size and configurations, a filtration chamber, a sample application port, fluid application surface of a filter, filtrate egress surface of a filter, and a capillary outlet to one or more capillary channels
Data Source
AI summary
This invention provides lateral flow filters with pore size gradients and with features to prevent peripheral flows around the filter. The filters can be laminated composites of two or more planar filter layers. Cartridges employing the filters can include a filtration chamber configured to retain the lateral flow filters including a port for sample application and a capillary channel for filtrate egress. The fluid egress port can be positioned to receive filtrate from one filter layer but not another.