Gas-Selective Membrane Temperature Modulation for Offset Reduction
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Solution Overview
Problem
Existing gas detection methods using temperature-dependent gas-selective membranes are hindered by offset signals that depend on temperature and sensor age, which interfere with the measurement signal.
Innovation Solution
The method involves periodically changing the membrane temperature between two non-zero values to record measurement signals at different temperatures, calculating the difference between these signals to reduce the offset component and enhance the detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the membrane temperature is adjusted to maximize gas permeability, then the detection sensitivity is improved, but the offset signal increases
Solution Approach 1:
The patent applies periodic temperature modulation of the membrane, alternating between a first temperature (maximizing permeability for target gas) and a second temperature (reducing offset signal). By periodically switching temperatures and synchronously demodulating the detector signal, the system extracts the AC component corresponding to target gas permeation while rejecting the DC offset component, thus resolving the contradiction between detection sensitivity and offset signal
Solution Approach 2:
The system uses feedback by continuously monitoring the detector signal at both temperature states and using synchronous demodulation to separate the target gas signal from the offset. The control system adjusts the heating element based on the detected signal to maintain optimal temperature modulation, creating a closed-loop feedback mechanism that resolves the contradiction
2Quantity of substance
If the membrane temperature is increased to enhance gas permeation, then the measurement signal increases, but the temperature-dependent offset component increases
Solution Approach 1:
Instead of maintaining continuously high temperature, the system uses periodic temperature modulation - switching between high temperature (for enhanced permeation during measurement phase) and low temperature (for offset reduction during reference phase). This periodic action allows the system to achieve high gas permeation only when needed while minimizing temperature-dependent offset during other phases
Solution Approach 2:
The system dynamically changes the membrane temperature parameter between two distinct states rather than maintaining a fixed high temperature. This parameter change strategy allows optimization of gas permeation during the measurement phase while reducing thermal offset during the reference phase, resolving the contradiction between permeation amount and temperature
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 effectively separates the offset signal from the useful gas detection signal, providing accurate gas detection by minimizing the influence of temperature-dependent offset components.
Implementation Method 1
gas-selective membrane with temperature-dependent permeability for the gas to be detected
Implementation Method 2
The temperature device is preferably a heater
Data Source
Figure 1~2
Figure 3
AI summary
In a method for the detection of gas using a gas-selective membrane (12), a temperature device (14) that is designed to change the temperature of the membrane (12), and a detector (20) that is designed to acquire a measurement signal (S) on the basis of the amount of gas passing through the membrane (12), provision is made for the following steps: - changing the temperature of the membrane (12) using the temperature device (14), - acquiring at least one first measured value (Hn, Hn+1, Hn+2) using the detector (20) at a time (t) at which the membrane temperature adopts a first temperature value (T1), - acquiring at least one second measured value (Ln, Ln+1) using the detector (20) at a time (t) at which the membrane temperature adopts a second temperature value (T2) different from the first temperature value, - calculating the difference between the two measured values and - using the difference to assess whether a gas to be detected is present.