Gradient Porosity Medical Filter for Bubble Removal

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Solution Overview

Problem

Current medical filters used in extracorporeal circuits during surgeries are inadequate in effectively capturing gaseous bubbles, which can lead to emboli formation and pose a risk to patient safety due to their uniform pore sizes, leading to insufficient residence time for bubble removal and potential complications.

Innovation Solution

The implementation of filters with a gradient of filter pore sizes at different portions, where the lower end has smaller pore sizes to restrict gaseous bubbles and increase residence time, while the upper end has larger pore sizes to facilitate blood flow and prevent bubble passage, enhancing the filter's ability to capture and remove gaseous emboli.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If uniform pore sizes are used in filters, then manufacturing is simple, but gaseous bubbles cannot be effectively captured due to insufficient residence time

Engineering Contradiction:
Improvebubble capture efficiencyVSAvoidfilter structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The filter employs different pore sizes at different locations: smaller pores at the bottom end and larger pores at the top end. This local variation in pore quality allows the filter to optimize bubble capture at the bottom while maintaining adequate flow through the top, resolving the contradiction between capture efficiency and structural simplicity.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The filter is divided into distinct segments with different pore characteristics - a bottom portion with smaller pores for bubble restriction and a top portion with larger pores for flow facilitation. This segmentation allows each portion to perform its specific function optimally, improving overall bubble capture efficiency without requiring a completely complex multi-component system.

Inventive Principle:
Principle #1Segmentation

2Reliability

If smaller pore sizes are used throughout the filter, then gaseous bubbles are restricted better, but blood flow is impeded and residence time is insufficient

Engineering Contradiction:
Improvebubble restriction capabilityVSAvoidblood flow rate
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

Smaller pore sizes are applied locally only at the bottom end of the filter where bubble restriction is most critical, while larger pore sizes are used at the top end to facilitate blood flow. This localized application of different pore qualities resolves the contradiction between bubble restriction and blood flow productivity.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The pore size parameter is changed along the length of the filter, with smaller pores at the bottom and larger pores at the top. This gradual or stepwise parameter change allows the filter to restrict bubbles effectively at the entry point while maintaining adequate flow capacity at the exit point, balancing reliability and productivity.

Inventive Principle:
Principle #35Parameter changes

3Productivity

If larger pore sizes are used throughout the filter, then blood flow is facilitated, but gaseous bubbles pass through and form emboli

Engineering Contradiction:
Improveblood flow facilitationVSAvoidemboli formation risk
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

Larger pore sizes are applied locally only at the top end of the filter where blood flow facilitation is needed, while smaller pores are used at the bottom end to prevent bubble passage. This spatial differentiation of pore qualities resolves the contradiction between productivity and harmful factor reduction.

Inventive Principle:
Principle #3Local quality

4Reliability

If uniform pore sizes are used, then filter structure is simple, but residence time for bubble removal is insufficient

Engineering Contradiction:
Improvebubble removal efficiencyVSAvoidblood residence time in filter
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The varying pore sizes create zones of different flow resistance within the filter, with smaller pores at the bottom creating a region of slower flow and longer residence time ideal for bubble removal, while larger pores at the top maintain overall flow efficiency.

Inventive Principle:
Principle #3Local quality

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 improves the efficiency of gaseous bubble removal, reduces the risk of emboli, enhances patient safety, and minimizes procedure complications by allowing longer blood residence time within the filter, thereby improving overall medical procedure efficacy and reducing healthcare costs.

Implementation Method 1

filters that have a gradient of filter pore sizes at different portions of the filters

Methodology Applied
Scientific EffectPhysical filtration through porous material: Filter (physical)

Implementation Method 2

enhance the filter's potential for capturing gaseous bubbles (potential emboli) that may be present in the blood

Methodology Applied
Scientific EffectBubble capture and removal: Bubble

Implementation Method 3

gaseous bubbles within the blood of an extracorporeal circuit presents a concern in relation to patient safety

Methodology Applied
Scientific EffectBuoyancy: Archimedes' Principle (Buoyancy)

Data Source

PatentEP3302624B1Filters with gradient porosities
Publication Date: 2020.11.25 TERUMO CARDIOVASCULAR SYSTEMS CORP
  • EP3302624B1 patent drawingFigure 1
  • EP3302624B1 patent drawingFigure 2
  • EP3302624B1 patent drawingFigure 3~4

AI summary

Multiple embodiments of medical filters are described. For example, this document describes extracorporeal blood filters that have a gradient of filter pore sizes at different portions of the filter element. The gradient of filter pore sizes may enhance the filter's potential for capturing and removing gaseous bubbles that may be present in the blood or other fluid that is flowing through the filter.