Ultrasonic Flow Sensor for Lung Clearance Index Measurement
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Solution Overview
Problem
Current methods for measuring and analyzing the multiple breath nitrogen washout process face challenges in achieving precise and synchronous measurements of gas flow and nitrogen concentration, leading to inaccuracies in determining lung volumes and ventilation inhomogeneity parameters due to the limitations of existing sensor technologies and measurement methods.
Innovation Solution
The use of ultrasonic flow and molecular mass measurement in combination with a fast-reacting CO2 sensor, based on IR absorption, to determine functional residual capacity, Lung Clearance Index, and other parameters, while compensating for time delays in gas flow and concentration signals through synchronization and calibration, allowing for accurate calculation of nitrogen concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If mass spectrometers are used to measure gas concentrations, then measurement precision and response time are improved, but device cost and maintenance requirements increase
Solution Approach 1:
The patent replaces the mass spectrometer (complex mechanical/electrical system) with a combination of ultrasonic flow sensor and infrared CO2 sensor. The ultrasonic sensor measures gas flow and molecular mass, while the IR sensor measures CO2 concentration. Together with calculations based on gas composition relationships, this substitutes the expensive mass spectrometer system with simpler, more cost-effective sensors that achieve the same measurement function.
2Ease of manufacture
If separate gas sensors are used to measure O2 and CO2 concentrations, then N2 concentration can be determined indirectly, but measurement precision deteriorates due to time delays between signals
Solution Approach 1:
The patent replaces the separate O2 and CO2 sensor system with an ultrasonic flow sensor that directly measures gas molecular mass. This substitution eliminates the time delay problem between separate sensors because the ultrasonic sensor provides direct measurement of the gas mixture properties without requiring synchronization of multiple separate measurements. The molecular mass measurement combined with CO2 concentration data directly yields accurate N2 concentration.
3Measurement precision
If flow and N2 concentration signals are recorded synchronously, then measurement precision is improved, but device complexity increases due to synchronization requirements
Solution Approach 1:
The patent merges the flow measurement and gas concentration measurement functions into a single integrated sensor system. The ultrasonic flow sensor simultaneously measures both gas flow rate and molecular mass (which relates to gas composition). This merging of measurement functions into one sensor eliminates the need for complex external synchronization systems, as the data from flow and concentration are inherently synchronized from the same measurement point and time.
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
This approach enables precise and cost-effective measurement of nitrogen washout processes, providing accurate lung function analysis with high long-term stability and adaptability for various patient groups, including neonatal to adult patients, and ventilated patients, with improved accuracy and reduced operational costs.
Implementation Method 1
Both flow velocity and the N2 signal must be measured with fast-reacting sensors
Implementation Method 2
The flow speed of the air and the molar mass in the breathing tube are determined using ultrasonic transit time measurement
Implementation Method 3
a fast-reacting CO2 sensor, usually based on the IR absorption method
Data Source
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AI summary
The invention relates to a device for measuring and analyzing the multiple-breath washout procedure, characterized in that an ultrasonic flow and molar mass sensor measures the instantaneous flow and molar mass of the gas inhaled and exhaled by the patient in the main stream.