Gas Sensor Recalibration Using Intermediary Reference Gas
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Solution Overview
Problem
Metal oxide gas sensors face challenges in accurately measuring absolute target gas concentrations due to unstable baseline resistance and errors caused by varying target gas baseline concentrations, especially in environments with low concentrations and contamination, leading to incorrect readings of gas ingress events.
Innovation Solution
The method involves recalibrating the gas sensor using a recalibration gas with a defined constant baseline concentration, such as hydrogen or methane, and employing sensors like ozone or humidity detectors to identify suitable recalibration environments, allowing for accurate determination of target gas concentrations by measuring the recalibration gas baseline resistance and updating calibration parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If baseline correction algorithm using target gas baseline concentration is used, then gas sensor readings can be normalized, but measurement precision deteriorates due to varying baseline concentrations in different environments
Solution Approach 1:
The patent introduces a recalibration gas (such as hydrogen or methane) as an intermediary substance with a defined constant baseline concentration. This recalibration gas serves as a mediator between the sensor and the target gas, providing a stable reference point for calibration that is independent of varying environmental target gas baseline concentrations. The sensor is calibrated using the recalibration gas to establish baseline resistance values, which then enables accurate measurement of target gas concentrations without being affected by environmental variations in target gas baseline.
2Adaptability or versatility
If gas sensor operates in high target gas concentration without prior clean air exposure, then baseline adjustment occurs, but measurement precision deteriorates due to strong underestimation of target gas concentrations
Solution Approach 1:
The patent performs preliminary calibration using a recalibration gas with a defined constant baseline concentration before the sensor is deployed to measure target gas concentrations. This preliminary calibration establishes accurate baseline resistance values in advance, preventing the sensor from incorrectly adapting its baseline when first exposed to high target gas concentrations in the field. The recalibration gas provides a known reference state that prepares the sensor for accurate measurements in varying environmental conditions.
Solution Approach 2:
The patent changes the calibration parameter from using target gas baseline concentration (which varies with environment) to using recalibration gas baseline concentration (which is defined and constant). By changing the reference substance used for calibration from the target gas itself to a different gas with stable known concentration, the sensor's baseline resistance is established based on a invariant parameter rather than a variable one, thereby maintaining measurement precision across different environments.
3Adaptability or versatility
If target gas baseline concentration varies significantly in different locations, then adaptability to local conditions improves, but measurement precision deteriorates due to error propagation from power law relationship
Solution Approach 1:
The patent introduces a recalibration gas as an intermediary reference substance that decouples the calibration process from environmental target gas baseline variations. The recalibration gas with its defined constant baseline concentration serves as a stable mediator that provides consistent calibration reference across all locations, preventing error propagation that would otherwise occur due to the power law relationship between target gas baseline concentration and measured concentrations.
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 enables high-accuracy identification of absolute target gas concentrations by stabilizing baseline resistance and reducing errors, ensuring reliable gas monitoring even in varying environments and during recalibration, thus improving the reliability of gas sensor readings.
Implementation Method 1
A metal oxide based gas sensor changes an electrical resistance of the sensing element, the material of which sensing element contains the metal oxide, as a function of a concentration of the gas desired to be detected
Implementation Method 2
a sensing element of a material including or consisting of metal oxide that typically is to be heated to become operational to a temperature in a range between 100° C. and 400° C.
Data Source
AI summary
A gas sensor includes a sensing element of a material including metal oxide and is sensitive to a target gas and to a recalibration gas different from the target gas. For recalibrating the gas sensor, a resistance of the sensing element is measured as an updated recalibration gas baseline resistance in a recalibration environment showing a recalibration gas baseline concentration.