Flexible-Wall Biological Fluid Filters for Handling and Centrifuging

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Solution Overview

Problem

Existing blood filters with rigid housings face challenges in construction, performance, and manufacturability, particularly in handling and centrifuging, while flexible housing filters require improvements in design and functionality.

Innovation Solution

A biological fluid filter assembly with flexible walls and a multi-layered filter medium, including a pre-filter, leukocyte removal layer, and a post-filter, sealed by inner and outer peripheral seals, allowing for efficient removal of microaggregates and leukocytes, with a third element providing support and air permeability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If rigid housing filters are used, then structural strength is improved, but handling and centrifuging capabilities deteriorate

Engineering Contradiction:
Improvestructural strengthVSAvoidhandling and centrifuging capabilities
Core Design Contradiction:
StrengthVSEase of operation

Solution Approach 1:

The patent applies flexible housing material (soft plastic or elastomer) to replace rigid housing, allowing the filter to withstand handling and centrifuging without breakage while maintaining structural integrity through flexible seals and support structures

Inventive Principle:
Principle #30Flexible shells and thin films

2Ease of operation

If flexible housing filters are used, then handling and centrifuging capabilities are improved, but structural strength deteriorates

Engineering Contradiction:
Improvehandling and centrifuging capabilitiesVSAvoidstructural strength
Core Design Contradiction:
Ease of operationVSStrength

Solution Approach 1:

The patent uses composite construction combining flexible housing material with rigid support elements (molded frame, peripheral seals, internal ribs) to achieve both flexibility for handling and structural strength for filtration integrity

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The filter is divided into functional segments: flexible housing for durability, rigid molded frame for structural support, peripheral seals for containment, and filter medium for filtration, each optimized for its specific function

Inventive Principle:
Principle #1Segmentation

3Reliability

If peripheral seals are added to flexible housing filters, then sealing performance is improved, but device complexity increases

Engineering Contradiction:
Improvesealing performanceVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent integrates multiple sealing functions into a single molded frame structure that combines peripheral seals, support ribs, and filter medium retention features, reducing overall device complexity while maintaining sealing performance

Inventive Principle:
Principle #5Merging (Combining)

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 flexible filter assembly effectively removes microaggregates and leukocytes, enhancing handling and centrifuging capabilities, while maintaining high air permeability and structural integrity.

Implementation Method 1

The filter assembly includes a filter medium disposed between the flexible housing walls. The filter medium includes at least first, second and third elements wherein the first element is made of or includes a material suitable for removing a component or particulate of a biological fluid

Methodology Applied
Scientific EffectFiltration: Filter (physical)

Implementation Method 2

the walls of the filter housing have been made of a rigid, typically polymeric, material. More recently, filters wherein at least the walls of the housing are made of a flexible material have been used in blood collection kits. Soft or flexible housing filters provide the advantage of being able to withstand handling and centrifuging without breakage of the filter

Methodology Applied
Scientific EffectFlexibility: Elasticity

Data Source

PatentEP3586889B1Biological fluid filters having flexible walls
Publication Date: 2025.10.29 FENWAL INC
  • EP3586889B1 patent drawingFigure 1~5
  • EP3586889B1 patent drawingFigure 6~8
  • EP3586889B1 patent drawingFigure 9~12

AI summary

Flexible housing filters for filtration of fluids and methods of making such filters are disclosed. The filters may include one or more peripheral seals in the flexible housing.