Gas Sensor Resistance Shape Analysis for Interference Rejection
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Solution Overview
Problem
Existing gas sensors face accuracy issues due to interference from other gases in the air when measuring a target gas, as they rely on changes in electric resistance caused by gas molecules adsorbed or desorbed on the sensor surface.
Innovation Solution
A gas sensor with a sensing layer that changes electric resistance through oxidation or reduction reactions, coupled with a processor that monitors and analyzes these changes using a sigmoid function to determine the target gas concentration, accounting for both oxidation and reduction reactions, and corrects for environmental factors like pressure, temperature, and humidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If gas sensors use a method of measuring gas concentration based on change in electric resistance caused by gas molecules adsorbed/desorbed on the sensor surface, then the measurement method is simple and cost-effective, but the accuracy is reduced due to interference from various gases contained in the air
Solution Approach 1:
The patent segments the gas sensing measurement process into distinct phases: an initial measurement phase in air (containing interfering gases) and a target gas introduction phase. By separately measuring and comparing the resistance changes in these two phases, the system can isolate and identify the contribution of the target gas from the background air gases, thereby improving measurement accuracy while maintaining the simplicity of resistance-based sensing.
2Measurement precision
If the sensor measures all gas molecules adsorbed on the surface, then the response is strong, but the selectivity for target gas is reduced due to contribution from other gases
Solution Approach 1:
The patent implements a feedback mechanism where the initial measurement in air serves as a reference baseline. When target gas is introduced, the system compares the new resistance change against this baseline feedback, allowing it to subtract or account for the known contribution of air gases. This feedback approach enables the sensor to maintain strong response signals while achieving better selectivity for the target gas.
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
Enhances the accuracy of gas concentration measurement by distinguishing between target gas and interfering gases, providing precise concentration determination through advanced signal processing and environmental corrections.
Implementation Method 1
a sensing layer including an electric resistance that changes by an oxidation reaction or a reduction reaction between gas molecules and the sensing layer
Implementation Method 2
a sensing layer including an electric resistance that changes by an oxidation reaction or a reduction reaction between gas molecules and the sensing layer
Implementation Method 3
a method of measuring a gas concentration based on a change in electric resistance caused by gas molecules adsorbed/desorbed on the surface of the sensors
Implementation Method 4
a method of measuring a gas concentration based on a change in electric resistance caused by gas molecules adsorbed/desorbed on the surface of the sensors
Data Source
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Figure 3A
AI summary
An apparatus for measuring a concentration of a target gas includes: a gas sensor including a sensing layer having an electric resistance that changes by an oxidation reaction or a reduction reaction between gas molecules and the sensing layer; and a processor configured to, in response to the target gas being introduced along with air into the gas sensor, monitor a change of the electric resistance of the sensing layer and determine the concentration of the target gas by analyzing a shape of the change of the electric resistance.