Multi-Channel Gas Sensor System with Adaptive Resistance Analysis
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Solution Overview
Problem
Conventional multi-channel gas sensor systems face resolution degradation when analyzing resistance values below 1 M ohms or above 10 M ohms, and the use of digital-to-analog converters can lead to circuit damage due to instantaneous high voltage application.
Innovation Solution
A multi-channel resistance-based gas sensor system that selects analysis modes (current mode, resistance mode, and external resistance mode) based on resistance ranges and determines current sources sequentially from least significant to most significant bit to prevent circuit damage, using pre-processing units and analog-to-digital converters to maintain high-resolution analysis across various resistance values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional sensor monitoring device uses a multi-channel sensor array to detect various gases simultaneously, then high-resolution signal detection is achieved, but resolution degradation occurs at relatively low sensing values (1 M ohms or smaller) or at relatively high sensing values (10 M ohms or greater)
Solution Approach 1:
The system dynamically switches between different analysis modes (current mode, resistance mode, external resistance mode) based on the detected resistance range. The control unit adjusts the operating parameters and circuit configuration according to the sensing value magnitude, enabling the system to maintain high resolution across the entire resistance range from 100 kOhms to 10 MOhms.
Solution Approach 2:
The system changes key parameters including the current source selection, mode switching, and analysis methodology based on the resistance range. For low resistance values, the system uses current mode with specific current sources; for medium values, resistance mode; and for high values, external resistance mode. This parameter adaptation resolves the contradiction between maintaining high resolution and covering wide resistance ranges.
2Ease of operation
If a digital-to-analog converter is used to determine the resistance range by flowing current from the most significant bit current source to the least significant bit current source, then the resistance value can be determined, but an instantaneous high voltage is applied if the resistance value is relatively large, which may damage the circuit
Solution Approach 1:
The patent inverts the conventional DAC scanning sequence by starting from the least significant bit current source (LSB) and progressing to the most significant bit current source (MSB). This reverse scanning order ensures that only small currents are applied initially, and only larger currents are applied after smaller ones have been tested, thereby preventing instantaneous high voltage application and circuit damage while still enabling accurate resistance determination.
Solution Approach 2:
The system performs preliminary current source activation starting from the LSB before attempting to activate larger current sources. This preliminary action sequence ensures that the circuit is progressively loaded with increasing current levels, preventing the sudden application of high voltage that would occur with conventional MSB-to-LSB scanning, thus protecting the circuit while maintaining measurement capability.
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
Enables high-resolution analysis of various resistance ranges without resolution degradation and prevents circuit damage by sequentially switching current sources, effectively managing voltage levels.
Implementation Method 1
a plurality of resistive type gas sensors; analyze, based on the selected mode, a sensing value obtained from any one of the gas sensor channels
Implementation Method 2
a first analog-to-digital converter (ADC) configured to convert the first voltage value to digital data
Data Source
AI summary
In a multi-channel resistance-based gas sensor system, the multi-channel array includes gas sensor channels respectively connected to resistive type gas sensors. The pre-processing unit selects a current mode, a resistance mode, or an external resistance mode, analyzes a sensing value obtained from any one of the gas sensor channels based on the selected mode and outputs a voltage value corresponding thereto. The analog-to-digital converter (ADC) converts the voltage value to digital data. The control unit controls the pre-processing unit to execute one of the current mode for analyzing a sensing value smaller than or equal to a preset first resistance value, the external resistance mode for analyzing a sensing value greater than or equal to a preset second resistance value greater than the preset first resistance value and the resistance mode for analyzing a sensing value between the preset resistance first value and the preset second resistance value.