Sensor Arrangement with Heat Moisture Exchanger Filter for CO2 Measurement
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Solution Overview
Problem
Existing methods for determining carbon dioxide concentration in medical device gases are often complex, expensive, and prone to inaccuracy due to temperature and moisture fluctuations during inhalation and exhalation, leading to cross-influences that affect sensor measurements.
Innovation Solution
A sensor arrangement with a heat and moisture exchanger filter is used to buffer, compensate, and smooth temperature and moisture differences in the measured gas, ensuring accurate carbon dioxide concentration determination by isolating these fluctuations from the measurement process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a hydrophobic barrier is used to prevent condensing moisture, then moisture protection is improved, but measurement accuracy deteriorates due to cross-influences from temperature and moisture fluctuations
Solution Approach 1:
A heat and moisture exchanger filter is introduced as an intermediary component between the measured gas and the sensor unit. This filter selectively exchanges heat and moisture with the gas stream, stabilizing temperature and humidity conditions before the gas reaches the sensor, thereby eliminating cross-influences on measurement accuracy while still allowing CO2 detection
Solution Approach 2:
The system changes the physical parameters (temperature and moisture content) of the measured gas by using a heat and moisture exchanger filter that actively regulates these parameters. The filter modifies the gas state to maintain stable conditions, preventing the temperature and moisture fluctuations that previously caused measurement errors
2Device complexity
If simple and cost-effective sensor methods are used, then device complexity and cost are reduced, but measurement reliability deteriorates due to sensitivity to temperature and moisture variations
Solution Approach 1:
The heat and moisture exchanger filter serves as a protective intermediary that shields the simple sensor from environmental variations. By stabilizing the gas conditions before measurement, the filter enables reliable operation of cost-effective sensor types that would otherwise be too sensitive to temperature and moisture changes
3Loss of time
If direct measurement of measured gas is performed, then response time is improved, but measurement accuracy deteriorates due to synchronous fluctuations in temperature and moisture during breathing phases
Solution Approach 1:
The heat and moisture exchanger filter acts as a buffer that decouples the direct connection between breathing phases and sensor measurements. It absorbs and releases heat and moisture synchronously with breathing, creating a stabilized intermediate gas stream that maintains measurement accuracy while preserving timely response
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 use of a heat and moisture exchanger filter in the sensor arrangement significantly improves the accuracy of carbon dioxide concentration measurements by stabilizing gas conditions, reducing measurement errors, and maintaining the integrity of other gas components, while being cost-effective and compact.
Implementation Method 1
at least one heat and moisture exchanger filter for filtering the branched-off measured gas
Implementation Method 2
at least one heat and moisture exchanger filter for filtering the branched-off measured gas
Implementation Method 3
the carbon dioxide concentration can be inferred by means of the heat conduction of a measured gas or of a gas sample at a sensor unit
Data Source
AI summary
A sensor arrangement (10) for a medical device (12), includes a sensor unit (11) for determining a carbon dioxide concentration in the measured gas, a branch line (14) for branching off the measured gas from a main line (15) of the medical device (12) and for sending the branched-off measured gas to the sensor unit (11). At least one heat and moisture exchanger filter (16, 17) filters the branched-off measured gas. A medical device (12) with the sensor arrangement (10), an exhalation valve (25) for the medical device (12) as well as a process for determining a carbon dioxide concentration are also provided.