Respiratory Mask Diffuser Venting for Quiet CO2 Exhaust

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Solution Overview

Problem

Existing respiratory therapy systems face challenges in minimizing noise and air drafts from patient interface vents while maintaining effective carbon dioxide removal, and issues with diffuser material wear and fiber detachment lead to potential obstruction of vent holes and auxiliary passages.

Innovation Solution

A mask assembly with a vent system featuring a diffuser material that includes strategically placed localised joint regions to bond fibers, offset from vent holes, and an auxiliary vent passage to ensure effective gas flow and prevent obstruction, while maintaining comfort and reducing noise.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If a vent hole is provided in the mask assembly to allow exhaled gas to escape, then gas flow exhaustion is improved, but bacteria and viruses can enter the patient's airway through the vent hole

Engineering Contradiction:
Improvegas flow exhaustionVSAvoidbacterial and viral contamination
Core Design Contradiction:
Loss of energyVSObject-affected harmful factors

Solution Approach 1:

The patent employs a hydrophobic membrane material with microporous structure that allows gas molecules to pass through while blocking larger particles such as bacteria and viruses. The membrane's pore size is specifically controlled to permit water vapor and gas diffusion while physically preventing microbial passage, thus resolving the contradiction between ventilation and contamination protection.

Inventive Principle:
Principle #31Porous materials

Solution Approach 2:

The patent changes the surface energy parameters of the membrane material by applying hydrophobic treatment, creating a surface that repels water and water-based contaminants while allowing gas permeation. This parameter change enables the membrane to differentiate between gas molecules (which can pass) and bacterial/viral particles suspended in liquid droplets (which are blocked), simultaneously achieving gas exhaustion and contamination prevention.

Inventive Principle:
Principle #35Parameter changes

2Object-affected harmful factors

If a hydrophobic membrane material is used to block bacteria and viruses, then contamination protection is improved, but water vapor transmission may be restricted

Engineering Contradiction:
Improvebacterial and viral blockingVSAvoidwater vapor transmission
Core Design Contradiction:
Object-affected harmful factorsVSLoss of substance

Solution Approach 1:

The hydrophobic membrane incorporates a controlled microporous structure where pore dimensions are optimized to allow water vapor diffusion while blocking liquid water and larger particles. The porosity level is specifically engineered to maintain breathability for gas exchange while providing effective filtration, thus preventing both contamination and water vapor restriction.

Inventive Principle:
Principle #31Porous materials

Solution Approach 2:

The patent utilizes a composite structure combining hydrophobic coating layers with porous substrate materials. This composite approach integrates the contaminant-blocking properties of hydrophobic surfaces with the breathability of porous structures, achieving simultaneous protection against bacteria/viruses and maintenance of water vapor transmission for comfortable patient use.

Inventive Principle:
Principle #40Composite materials

3Stability of the object's composition

If a diffuser is provided at the vent hole, then gas flow distribution is improved, but the complexity of the vent structure increases

Engineering Contradiction:
Improvegas flow distributionVSAvoidvent structure complexity
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The patent merges the diffuser function with the membrane material itself by integrating flow distribution features directly into the membrane structure. Rather than adding a separate diffuser component, the membrane is designed with patterns or structures that inherently distribute gas flow evenly, thus achieving improved gas flow distribution while minimizing structural complexity.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The membrane material is designed to perform multiple functions simultaneously: filtration of contaminants, regulation of gas flow, and distribution of exhaust. By making the membrane multi-functional, the patent eliminates the need for separate diffuser components, reducing overall vent structure complexity while maintaining effective gas flow distribution.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 effectively minimizes noise and air drafts, maintains efficient carbon dioxide removal, and prevents vent hole obstruction, enhancing patient safety and comfort by reducing the risk of suffocation from CO2 accumulation.

Implementation Method 1

a hydrophobic membrane material allowing water vapour to pass through the membrane material whilst blocking liquid water

Methodology Applied
Scientific EffectHydrophobic effect: Hydrophobe

Implementation Method 2

a microporous structure allowing gas diffusion whilst preventing passage of particles larger than the pores

Methodology Applied
Scientific EffectDiffusion: Diffusion

Data Source

PatentEP4454692B1Diffuser for a component of a respiratory therapy system
Publication Date: 2026.04.29 FISHER & PAYKEL HEALTHCARE LTD
  • EP4454692B1 patent drawingFigure 1
  • EP4454692B1 patent drawingFigure 2~3
  • EP4454692B1 patent drawingFigure 4~5

AI summary

This disclosure provides a mask assembly for respiratory therapy, comprising: a vent for exhausting gas flow from an interior of the mask assembly, the vent comprising at least one vent hole; and a diffuser material defining a diffusing area sufficient to cover the vent hole and having a periphery. A region of the diffusing area of the diffuser material includes a localised j oint region in which multiple fibres of the diffuser material are bonded or interlocked together. The location of the localised joint region is offset from the vent hole. Further embodiments are disclosed in which the shape of the diffusing material matches the shape of a vent hole array, or has other properties related to the vent hole array or the shape or other features of the vent.