Static Mixer for Respiratory Gas Composition Sensing
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Solution Overview
Problem
Respiratory therapy systems face inaccuracies in gas composition sensing due to poor mixing of gases, particularly when oxygen and air are not properly mixed, leading to suboptimal gas therapy effectiveness.
Innovation Solution
Incorporating a static mixer upstream of the gas composition sensing region to uniformly mix gases, utilizing baffles and a bridge to direct and swirl gas flows, ensuring accurate gas composition measurement by an ultrasonic transducer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If gases are delivered through separate conduits without mixing, then gas delivery is simple and direct, but gas composition sensing accuracy deteriorates due to poor mixing
Solution Approach 1:
A static mixer is introduced as an intermediary component between the separate gas conduits and the sensing region. The mixer contains multiple baffles that force the gas streams to intermix through a tortuous flow path, ensuring homogeneous gas composition before reaching the sensor without requiring complex active mixing mechanisms
Solution Approach 2:
The static mixer is segmented into multiple sections with alternating baffles positioned at different angles. Each baffle segment creates localized flow disruption and redirection, progressively mixing the gas streams through multiple small-scale interactions rather than requiring a single complex mixing event
2Reliability
If multiple gases are delivered to maintain control of gas ratios, then gas therapy effectiveness is improved, but measurement accuracy deteriorates when gases are not properly mixed
Solution Approach 1:
The static mixer performs preliminary mixing of multiple gas streams before they reach the sensing region. By pre-mixing the gases in a controlled manner through fixed baffles, the system ensures that the sensor receives a representative sample of the actual gas composition, enabling reliable feedback for therapy control
3Ease of operation
If an ultrasonic transducer measures gas composition in a non-uniform flow, then sensing is simple, but measurement accuracy deteriorates due to spatial variation in gas composition
Solution Approach 1:
The static mixer creates a localized region of homogeneous gas composition immediately upstream of the sensing point. The baffles are strategically positioned to ensure that within the measurement zone, the gas composition is uniform, allowing the ultrasonic transducer to accurately represent the bulk gas composition without needing to account for spatial variations
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 static mixer enhances the accuracy of gas composition sensors, ensuring reliable readings and consistent gas delivery, thereby improving the therapeutic efficacy of respiratory therapy systems.
Implementation Method 1
An ultrasonic transducer, for example, can be used to measure or estimate the composition of a gas mixture on a plane using a time-of-flight calculation
Implementation Method 2
The first baffle may extend in a downstream direction at an angle offset from the horizontal plane... The second baffle may extend in a downstream direction at an angle offset from the horizontal plane
Data Source
AI summary
A respiratory therapy system can have a flow generator adapted to provide gases to a patient. A gas passageway can be located in-line with the flow generator. The gas passageway can have a first portion adapted to receive a first gas and a second portion adapted to receive a second gas. The gas passageway can have a static mixer downstream of the first and second portions.