Periodic Temperature Cycling for Gas Sensing Accuracy
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Solution Overview
Problem
Existing chemoresistive gas sensors face challenges in accurately distinguishing between gases in mixtures due to cross-sensitivities and instability, particularly with high temperature requirements that lead to energy consumption and miniaturization issues, and lack effective feature extraction methods.
Innovation Solution
A gas sensing device utilizing chemoresistive sensors with a periodic temperature profile, preprocessing, feature extraction, and machine learning algorithms to generate accurate gas concentration results, incorporating graphene or reduced graphene sensors functionalized with specific chemicals for enhanced sensitivity, and employing time and frequency domain analysis to mitigate cross-sensitivities and drift.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high temperature is used for chemoresistive gas sensing, then gas sensitivity is improved, but energy consumption increases and miniaturization becomes complex
Solution Approach 1:
The patent implements periodic temperature cycling of the chemoresistive sensor, alternating between high temperature (for gas sensitivity) and low temperature (for energy saving). This periodic action allows the sensor to achieve adequate gas detection performance while significantly reducing average energy consumption compared to continuous high-temperature operation
Solution Approach 2:
The patent dynamically adjusts the sensor operating temperature based on detection needs, transitioning between different temperature states. This dynamic temperature control enables the system to optimize the balance between sensing performance and energy consumption, avoiding the need for continuous high-temperature operation
2Measurement precision
If high temperature is used for chemoresistive gas sensing, then gas sensitivity is improved, but device complexity for miniaturization increases
Solution Approach 1:
By using periodic temperature cycling instead of continuous high temperature, the thermal management requirements are relaxed, enabling more compact and simpler device designs that can be miniaturized more effectively while maintaining adequate sensing performance
3Device complexity
If single sensor is used for gas detection, then device simplicity is maintained, but ability to differentiate gases in mixture is insufficient
Solution Approach 1:
The patent applies periodic temperature cycling to a single chemoresistive sensor, creating time-varying response patterns that encode gas composition information. This temporal modulation enables a single sensor to differentiate between multiple gases in mixture, achieving the functionality of a sensor array without the corresponding complexity
4Measurement precision
If conventional signal processing is used, then processing simplicity is maintained, but gas concentration estimation accuracy is insufficient
Solution Approach 1:
The patent replaces conventional mechanical/signal processing methods with machine learning algorithms that automatically extract features from the temperature-cycled sensor signals. This substitution enables accurate gas concentration estimation from complex periodic signals while managing processing complexity through intelligent algorithms
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
The device effectively differentiates gases in mixtures with improved accuracy and stability, reducing energy consumption and enabling miniaturization, while addressing calibration inaccuracies and environmental effects, and can be used in various applications including portable devices.
Implementation Method 1
a heating arrangement configured in such way that the gas sensors are heated according to a periodic temperature profile
Implementation Method 2
one or more chemoresistive gas sensors, wherein each of the gas sensors is configured for generating signals corresponding to concentrations of the one or more gases
Implementation Method 3
The signals are typically electrical signals, which refer to electrical properties of the sensing material of one of the gas sensors
Implementation Method 4
one or more time domain feature values, which are based on time domain characteristics of one of the preprocessed signal samples
Implementation Method 5
one or more frequency domain feature values, which are based on frequency domain characteristics of one of the preprocessed signal samples
Data Source
AI summary
A gas sensing device includes chemo-resistive gas sensors, wherein each of the gas sensors generates signals corresponding to concentrations of gases in a mixture of gases; a heating arrangement for heating gas sensors according to a periodic temperature profile; a preprocessing processor for receiving the signals from each of the gas sensors and for preprocessing the received signals to generate a preprocessed signal sample for each of the gas sensors for each period of the periodic temperature profile; a feature extraction processor configured for receiving the preprocessed signal samples and for extracting for each of the periods a set of feature values from the preprocessed signal samples received for the respective period; and a gas concentration processor for receiving sets of feature values.