Composite Microporous Filter for Ostomy Pouch Leak Resistance
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Solution Overview
Problem
Ostomy pouch filters are prone to contamination and moisture intrusion, leading to reduced deodorization effectiveness and gas flow, with existing membranes either allowing water intrusion or exhibiting high backpressure, and often causing stoma irritation due to exposed edges.
Innovation Solution
A filter assembly featuring a composite microporous membrane with an expanded polytetrafluoroethylene layer and a hydrophobic polyester support layer, welded to the inside of the pouch to prevent liquid ingress and maintain gas flow, while avoiding direct exposure to the stoma.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If a microporous membrane is used to protect the filter from liquid intrusion, then the filter protection duration is improved, but the gas flow properties deteriorate due to high backpressure
Solution Approach 1:
The patent employs a composite microporous membrane structure consisting of multiple layers with different properties: an outer hydrophobic layer for liquid barrier, a middle layer for mechanical strength, and an inner layer optimized for gas flow. This multi-layer composite approach allows simultaneous achievement of long-term liquid protection and high gas flow rates by distributing functions across different material layers.
Solution Approach 2:
Different regions and layers of the membrane are designed with locally optimized properties: the outer surface has enhanced hydrophobicity for liquid repulsion, while inner regions maintain higher porosity for gas flow. The membrane thickness and pore size vary through the layers to balance protection duration and gas flow characteristics at different depths.
2Duration of action of stationary object
If a microporous membrane is used to protect the filter from liquid intrusion, then the filter protection duration is improved, but the membrane structure becomes more complex
Solution Approach 1:
The complex protection requirement is solved through a composite membrane structure where multiple specialized layers work together. Each layer has a specific function (liquid barrier, structural support, gas flow optimization) and the composite structure achieves extended protection duration that would be difficult to obtain with a single-layer membrane.
Solution Approach 2:
The membrane is segmented into distinct functional layers, each optimized for a specific purpose. This segmentation allows independent optimization of each layer's properties while maintaining overall system performance, making the complex protection requirement manageable through modular design.
3Reliability
If the membrane is welded to the pouch, then the membrane sealing is improved, but the stoma irritation occurs due to exposed edges
Solution Approach 1:
A connecting film or intermediary layer is introduced between the microporous membrane and the pouch body. This intermediary serves multiple functions: it provides a secure welding interface for reliable sealing, while its soft, biocompatible material properties prevent direct contact irritation to the stoma. The intermediary acts as a buffer that decouples the sealing requirement from the irritation problem.
Solution Approach 2:
The connecting film is designed as a flexible, thin-walled structure that can be securely welded to both the membrane and pouch while maintaining softness and flexibility. This flexible film conforms to the stoma area without creating rigid edges that would cause irritation, while still providing adequate sealing when welded.
4Reliability
If the filter is positioned to maximize deodorization, then the deodorizing capability is improved, but the filter becomes vulnerable to waste material contact
Solution Approach 1:
The microporous membrane acts as an intermediary barrier between the filter and the pouch interior environment. It allows gas molecules to pass through for deodorization while blocking larger waste material particles and liquids. This intermediary layer enables the filter to maintain optimal positioning for deodorization effectiveness while being protected from direct contamination by waste material.
Solution Approach 2:
The microporous membrane provides size-selective filtration with pore dimensions that permit gas molecules to pass through for deodorization function while physically blocking larger waste material particles and liquid droplets. This porous structure enables simultaneous achievement of deodorization effectiveness and filter protection from contamination.
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 solution provides superior leak resistance and deodorization capacity for extended periods, maintaining gas flow and preventing irritation, with demonstrated performance of over 5 days with mineral oil and 5 days of water exposure without leakage.
Implementation Method 1
a composite two sided microporous membrane at least partly covering said filter for preventing ingress of liquids into the filter, said membrane being comprised of an expanded polytetrafluoroethylene layer on one side and a support layer of hydrophobic material on the other side
Implementation Method 2
Previous filter designs have employed microporous membranes that permit flow of gases into the filter but prevent the passage of stool or liquid through the membranes and into the filter
Implementation Method 3
a porous filter containing deodorizing material for deodorizing gas passing therethrough
Data Source
Figure 1
AI summary
A filter assembly for an ostomy pouch includes a composite microporous membrane, a filter and a connecting film for connecting the membrane to the ostomy pouch.