Electrochemical Gas Sensor Slope Ratio Analysis
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Solution Overview
Problem
Existing methods for determining the concentration of electrochemical substances in gas samples, such as breath alcohol measurement, face challenges in maintaining long-term stability due to aging of the measuring cell and temperature effects, which can be misinterpreted by additional substances, leading to unreliable results.
Innovation Solution
Analyzing the slopes of the electric value curve in specific intervals after exceeding the maximum and comparing the ratio of these slopes to a reference value, allowing for reliable detection of electrochemical substances independent of cell aging and temperature, with options for invalidating or correcting measurements based on deviations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If the measuring cell is used over time, then the electrochemical processes occur, but the internal resistance increases due to aging, leading to slower electrochemical processes and changed curve profile
Solution Approach 1:
The patent applies feedback by continuously monitoring the curve profile characteristics (slope ratios) during measurement and comparing them against reference values. When deviations indicate aging effects, the system can compensate or adjust measurements, maintaining reliability throughout the measuring cell's operational life.
Solution Approach 2:
The patent changes the evaluation parameter from simple area integration to slope ratio analysis of the curve profile. This parameter transformation allows differentiation between aging effects and actual substance presence, enabling reliable measurements even as the measuring cell ages.
2Temperature
If the temperature of the measuring cell decreases, then the electrochemical processes slow down, but the curve profile changes in a way that mimics the presence of additional substances
Solution Approach 1:
The system uses feedback by comparing the measured slope ratio against reference values to detect temperature-induced changes. When temperature causes the curve profile to flatten, the feedback mechanism identifies this as an artifact rather than actual substance presence, preventing measurement errors.
Solution Approach 2:
The slope ratio acts as an intermediary parameter that mediates between the raw signal and the concentration calculation. This intermediary allows the system to separate true concentration information from temperature-induced artifacts, maintaining measurement precision across varying temperatures.
3Quantity of substance
If additional electrochemical substances are present in the gas sample, then the electrochemical processes are slowed, but the curve profile changes similarly to aging effects, making detection difficult
Solution Approach 1:
The patent segments the curve profile analysis into distinct intervals (first interval near maximum, second interval near reference line) and calculates slope ratios for each. This segmentation allows the system to detect characteristic patterns that differentiate between aging effects and actual substance presence, improving detection reliability.
Solution Approach 2:
The patent uses analogies to color changes - differentiating between the 'color' (curve profile shape) caused by aging versus the 'color' caused by additional substances. By analyzing specific slope ratios in different intervals, the system can distinguish between these different causes, ensuring reliable detection.
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 enhances the reliability of electrochemical measurements by distinguishing between aging effects and additional substances, ensuring accurate results and reducing the impact of external factors, making the measurements suitable for legal expert opinions.
Implementation Method 1
an electrochemical measuring cell (48) for determining an electrochemical substance in a gas sample (42) by means of a measured electric value (16), which changes over time (14), of the electrochemical measuring cell (48)
Data Source
AI summary
A process is provided for verifying an electrochemical substance in a gas sample. The process generates in an electrochemical sensor a measured electric value changing over time with a characteristic rising from a reference line to a maximum and again declining to the reference line. The percentage of the electrochemical substance in the gas sample is determined in an analysis circuit by setting a first interval and a second interval in the range of the characteristic after the maximum has been exceeded. The first interval includes the range of the characteristic in the vicinity of the maximum and the second interval includes the range of the maximum in the vicinity of the reference line. The electrochemical substance is determined by determining the ratio of the slopes of the first and second intervals and by comparison with a reference value of the ratio of the slopes of the first and second intervals.