Dual-Sensing Gas Detection with Environmental Compensation
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Solution Overview
Problem
Gas sensing devices, particularly MOX devices, face challenges in accuracy due to environmental factors like temperature and humidity variations, and material aging, leading to unstable oxygen adsorption and sensitivity issues.
Innovation Solution
A gas concentration sensing method utilizing a gas sensing device with a reference sensing portion and a target sensing portion, where the sensitivity of the reference portion is lower than the target portion, allowing for calibration through detected immittance values and correlation functions to calculate accurate target gas concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a MOX gas sensing device is used to detect target gas concentration, then the device can provide gas sensing function, but the detection accuracy deteriorates due to environmental factors (temperature, humidity) and material aging causing unstable oxygen adsorption and sensitivity variation
Solution Approach 1:
The sensing device is divided into two independent sensing portions: a target sensing portion that detects both target gas and environmental factors, and a reference sensing portion that detects only environmental factors. By segmenting the sensing functions, the system can separately measure and compensate for environmental interference, thereby maintaining detection accuracy despite environmental variations and material aging.
Solution Approach 2:
The reference sensing portion acts as an intermediary that measures environmental factors (temperature, humidity) affecting the target sensing portion. This intermediary measurement enables the system to calculate compensation values that correct the target gas detection results, eliminating the harmful effects of environmental variations on detection accuracy.
2Measurement precision
If the sensitivity of the sensing portion is increased to improve detection accuracy, then the response to target gas is enhanced, but the sensitivity to environmental interference is also increased
Solution Approach 1:
The sensing system is segmented into a target sensing portion with high sensitivity to both target gas and environmental factors, and a reference sensing portion with sensitivity only to environmental factors. This segmentation allows the high-sensitivity target sensing portion to maintain its detection accuracy while the reference portion separately captures environmental interference for compensation.
Solution Approach 2:
The reference sensing portion provides feedback information about environmental factors to the control unit, which then calculates compensation values and adjusts the target gas detection results. This feedback mechanism enables the system to maintain high sensitivity to target gas while eliminating environmental interference through real-time compensation.
3Measurement precision
If a reference sensing portion with lower sensitivity to target gas is added to the device, then environmental compensation capability is improved, but the device complexity increases
Solution Approach 1:
The reference sensing portion and target sensing portion are merged into a single integrated sensing device structure, sharing common components such as the heater and substrate. This merging approach enables environmental compensation functionality to be added without proportionally increasing overall device complexity, as the two sensing portions can be fabricated together on the same platform.
Data Source
AI summary
A gas sensing device is adapted to detect a concentration of a target gas. The gas sensing device comprises a dielectric layer, a reference sensing portion, a target sensing portion, and a controller. The dielectric layer is disposed on a surface. The reference sensing portion and the target sensing portion are respectively disposed on a supporting side of the dielectric layer, with said supporting side facing away from the surface. The reference sensing portion includes a first conductive layer and a first sensing layer with low sensitivity to the target gas. The target sensing portion includes a second conductive layer and a second sensing layer with high sensitivity to the target gas. The controller obtains the immittance values of the first conductive layer and the second conductive layer, and calculates a concentration value of the target gas according to the immittance values and a correlation function.