Spirometer Breathing Tube Compound Membrane
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Solution Overview
Problem
Conventional spirometers face challenges in accurately measuring airflows across a wide range of breathing rates due to linear or exponentially increasing resistance, which affects measurement precision and can lead to cross-contamination risks.
Innovation Solution
A disposable breathing tube with a compound membrane comprising two flexible sheets connected along the periphery, featuring overlapping flaps that create pressure differentials and varying resistance to airflow, allowing for non-linear voltage vs. airflow response curves and minimizing re-use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single membrane with linear or exponential resistance is used, then the structure is simple, but measurement precision deteriorates across wide airflow ranges
Solution Approach 1:
The membrane is divided into multiple discrete elements (first membrane element and second membrane element) with different resistance characteristics. Each element handles specific airflow ranges, with the first element optimized for lower flows and the second for higher flows, achieving precise measurement across the full range without requiring a single complex membrane design
Solution Approach 2:
The membrane assembly combines multiple membrane elements with different resistance profiles (linear and exponential) to create a composite structure. This composite approach allows the system to leverage the advantages of each material type, achieving both simplicity and measurement precision across varying airflow conditions
2Reliability
If disposable breathing tubes are used, then cross-contamination risk is reduced, but manufacturing cost increases
Solution Approach 1:
The breathing tube incorporating the membrane assembly is designed as a disposable component. This allows the use of cost-effective materials and manufacturing processes while ensuring reliability by eliminating cross-contamination risks between patients. The membrane's modular design facilitates efficient mass production, offsetting the per-unit cost of disposability
3Measurement precision
If high resistance membrane is used, then measurement sensitivity is improved, but airflow restriction increases
Solution Approach 1:
The membrane assembly provides dynamically varying resistance that adapts to airflow conditions. At low airflow rates, the first membrane element provides higher resistance for sensitive measurement. As airflow increases, the second membrane element engages to maintain appropriate resistance levels, preventing excessive airflow restriction while preserving measurement sensitivity across the full operating range
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 precise airflow measurement across a broad range while discouraging re-use and reducing cross-contamination risks through a non-linear resistance profile and disposable design.
Implementation Method 1
The compound membrane creates pressure differentials across the breathing tube that are used by the spirometric measuring device to compute airflows
Implementation Method 2
the flap of the first sheet overlaps the flap of the second sheet so as to present a higher relative resistance to airflow through the breathing tube at lower airflows
Data Source
AI summary
A compound membrane breathing tube for use in spirometric applications is provided. The compound membrane comprises a first sheet and a second sheet of flexible sheeting connected together along the periphery thereof, and each of the sheets has an opening cut therethrough to create a flap. The flap of the first sheet overlaps the flap of the second sheet so as to present a higher relative resistance to airflow through the breathing tube at lower airflows.