Filter Membrane Integrity Testing With Pressure-Gradient Gas Screening

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Solution Overview

Problem

Existing methods for testing the integrity of filters, particularly those with compartments containing particulate matter, often produce false positives and fail to accurately distinguish between intact and defective filters.

Innovation Solution

A process involving the use of specific testing fluids and gases to establish a pressure gradient across compartments of a filter, monitoring the pressure or gas flow to identify defects in membranes, especially those with particulate matter, using nitrogen, air, noble gases, or perfluorinated alkanes as testing gases and aqueous solutions of polysorbates or salts as testing liquids.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional testing methods (bubble point test) are used to check filter membrane integrity, then the testing process can identify membrane pores larger than a predetermined limit, but the method produces false positives and fails to accurately distinguish between intact and defective filters when particulate matter is present

Engineering Contradiction:

Improvedetection accuracy of membrane defectsVSAvoidfalse positive rate in filter testing

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent changes the physical parameters of the testing system by selecting specific testing liquids and gases with optimized properties (surface tension, density, solubility) to achieve more accurate defect detection. The selection criteria for testing liquids include surface tension between 20-70 mN/m and for gases include low solubility in the membrane material, which fundamentally alters the testing conditions to eliminate false positives while maintaining detection accuracy.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces an intermediary substance (testing liquid or gas) that mediates between the pressure source and the membrane to enable accurate defect detection. The intermediary is carefully selected based on its physical properties to interact with the membrane and particulate matter in a controlled manner, allowing differentiation between intact filters and those with actual defects.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If a pressure gradient is applied across the filter membrane to test integrity, then gas flow through the membrane can be monitored to detect defects, but the presence of particulate matter interferes with accurate detection

Engineering Contradiction:

Improvedefect detection precisionVSAvoidinterference from particulate matter

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent changes the physical parameters of the testing environment by selecting testing substances with specific properties that minimize interaction with particulate matter while maintaining sensitivity to membrane defects. The gas phase testing with low-solubility gases reduces the harmful effect of particulate matter by eliminating liquid-gas interface phenomena that cause false readings.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent converts the presence of particulate matter from a harmful factor into a beneficial indicator by selecting testing conditions where particulate matter remains suspended or settled in a predictable manner, allowing its presence to be distinguished from actual membrane defects through the specific response patterns of the testing substance.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Ease of operation

If conventional testing liquids and gases are used without specific selection criteria, then the testing process is simple to perform, but the accuracy of defect identification is reduced

Engineering Contradiction:

Improvetesting process simplicityVSAvoidmembrane integrity detection accuracy

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The patent establishes specific parameter ranges for testing liquids (surface tension 20-70 mN/m, density 0.8-1.2 g/cm³) and gases (solubility <0.01 mol/L·atm) that optimize both detection accuracy and operational simplicity. These defined parameters provide clear selection criteria that maintain ease of operation while significantly improving measurement precision compared to conventional unguided substance selection.

Inventive Principle:

Principle #35Parameter changes

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 process provides reliable and fast identification of defective filters, even those with particulate matter, reducing false positives and enhancing the accuracy of filter integrity testing.

Implementation Method 1

introducing a testing gas into one of the compartments, displacing the testing liquid from the compartment, and establishing a pressure gradient between the compartments

Methodology Applied

Scientific EffectPressure gradient: Pressure Gradient

Implementation Method 2

monitoring the pressure gradient between the compartments or measuring flow of the testing gas through the membrane

Methodology Applied

Scientific EffectDiffusion: Diffusion

Data Source

PatentUS12623189B2Process for testing filters

Publication Date: 2026.05.12 GAMBRO LUNDIA AB

AI summary

The present disclosure relates to a process for testing the integrity of membranes in a filter module. Specifically, the process is applied to filters for extracorporeal blood treatment, in particular, filters comprising both filter membranes and particulate material.