Gas Sensor Humidity Equilibration via Permeable Membrane
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Solution Overview
Problem
Existing gas measurement methods struggle to effectively remove the influence of specific gases like water vapor from sample gases, particularly in portable and low-cost devices, where complex device configurations and controls are not feasible.
Innovation Solution
A measurement method that equilibrates the humidity of a reference gas and a sample gas using a water vapor permeable membrane, allowing the gases to be alternately supplied to a sensor, thereby canceling out the influence of water vapor on the measurement results.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If water vapor is removed from sample gas using conventional methods (cryocooler, desiccant, ion exchange membrane), then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent combines the reference gas path and sample gas path through a permeable membrane, allowing water vapor equilibration between the two paths. This merging approach eliminates the need for separate complex water vapor removal systems for each path, reducing overall device complexity while maintaining measurement precision.
Solution Approach 2:
The permeable membrane acts as an intermediary between the reference gas and sample gas, selectively allowing water vapor to pass through while preventing complete mixing of the gases. This mediator enables water vapor equilibration without requiring complex mechanical removal systems.
2Measurement precision
If water vapor is removed using active systems (cryocooler, pump), then measurement precision is improved, but ease of operation deteriorates
Solution Approach 1:
The system uses the sample gas itself to provide water vapor to the reference gas path through the permeable membrane. This self-service mechanism eliminates the need for external water vapor sources or complex active control systems, simplifying operation while maintaining precision.
Solution Approach 2:
The system alternates between introducing sample gas and reference gas to the sensor in periodic cycles. During reference gas introduction, water vapor equilibrates through the membrane; during sample gas introduction, measurement occurs. This periodic operation simplifies control compared to continuous active water vapor removal.
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 method significantly reduces the impact of water vapor on gas sensor measurements without requiring complex device configurations or active control systems, making it suitable for portable and low-cost devices.
Implementation Method 1
connecting a flow path of the reference gas and a flow path of the sample gas to each other via a permeable membrane for the specific gas
Data Source
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AI summary
The present invention suppresses an adverse effect caused when an additional gas such as water vapor is mixed in a sample gas or the like that is subjected to gas measurement. In an embodiment of the present invention, in gas measurement for analyzing sensor output signals obtained by alternately supplying a sample gas and a reference gas to a sensor element while alternately switching between the sample gas and the reference gas, the sample gas and the reference gas pass through a humidity equilibration device partitioned by a water vapor permeable membrane, and then are supplied to the sensor element. As a result, since both gases have substantially the same value of humidity at the time of being supplied to the sensor element, influences of water vapor are substantially cancelled out in signals output from the sensor element by the alternate supply of the sample gas and the reference gas.