Tortuous-Path Droplet Bandpass Filter for Sterilant Aerosols
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Solution Overview
Problem
Existing sterilization methods using mist generators produce a wide range of droplet sizes, with larger droplets often condensing on sterilized articles, leading to inefficiencies and safety hazards due to residual sterilant, and existing filtration methods are costly, complex, or impractical for medical sterilizers.
Innovation Solution
A method and apparatus using a tortuous pathway with impactors and bends to selectively remove larger droplets by causing them to impact the conduit walls, allowing smaller droplets to pass through, achieving a predetermined droplet size distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a mist generator is used to produce sterilant aerosol, then sterilization coverage is improved, but droplet size distribution becomes uncontrolled with larger droplets forming
Solution Approach 1:
The invention segments the droplet population by size using a tortuous flow pathway with multiple bends. The pathway is designed so that smaller droplets (1-10 microns) can navigate the bends and reach the sterilization chamber, while larger droplets (10-100 microns) impact against the conduit walls and are removed. This segmentation resolves the contradiction by allowing broad sterilant coverage while precisely controlling which size ranges reach the articles.
Solution Approach 2:
The tortuous flow pathway acts as an intermediary device between the mist generator and sterilization chamber. It selectively removes larger droplets through impaction against conduit walls during direction changes, while allowing smaller effective droplets to pass through. This intermediary function resolves the contradiction by filtering the aerosol stream to achieve controlled droplet size distribution without modifying the mist generator itself.
2Productivity
If larger droplets are allowed in the mist stream, then sterilant delivery efficiency is improved, but droplet coalescence on articles increases causing wet surfaces
Solution Approach 1:
The invention applies preliminary action by removing larger droplets from the aerosol stream before they reach the sterilization chamber and contact the articles. The tortuous flow pathway with its multiple bends causes larger droplets to impact and be removed upstream, preventing their subsequent coalescence on article surfaces. This preliminary removal resolves the contradiction by eliminating the source of wet surfaces while preserving smaller droplets that can effectively sterilize without coalescing.
3Manufacturing precision
If existing filtration methods are used to remove larger droplets, then droplet size control is improved, but device complexity and cost increase
Solution Approach 1:
The invention applies self-service by using the existing aerosol flow dynamics and conduit geometry to achieve droplet size separation without additional active filtration components. The tortuous flow pathway uses the kinetic energy and inertia of the flowing aerosol itself to cause larger droplets to impact and be removed. This self-service approach resolves the contradiction by achieving droplet size control through clever use of flow physics rather than complex mechanical or electronic filtration systems.
Solution Approach 2:
The invention replaces expensive, complex filtration systems with a simple, low-cost tortuous flow pathway that can be integrated into existing sterilizer conduits. The pathway relies on passive impaction mechanisms rather than expensive filters, membranes, or active control systems. This simple, inexpensive solution resolves the contradiction by achieving effective droplet size control without increasing device complexity or cost.
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
Efficiently reduces larger droplets while preserving smaller, effective droplets, minimizing sterilant waste and ensuring dry sterilized articles, thus enhancing safety and reducing cycle times and costs.
Implementation Method 1
the tortuous pathway comprises at least one impactor region located at a position adjacent to a flow direction change from a first input flow direction to at least one first output flow direction, and wherein a first portion of the droplets impact and remain at the impactor region
Data Source
AI summary
A droplet bandpass filter and method of modifying droplet size distribution of a population of droplets suspended in a gas. Droplets suspended in a gas are flowed through a bandpass filter having a tortuous pathway which comprises at least one impactor region located at a position adjacent to a flow direction change. Larger droplets impact at the impactor region while smaller droplets remain suspended in the gas and flow in the first output direction. Other flow restrictors may advantageously be included in the tortuous pathway. The filter is particularly useful in delivering sterilant aerosols (e.g. peroxides) with reduced populations of large droplets.