Gas Sensor Impedance Linearity Control
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Solution Overview
Problem
Conventional gas sensors, particularly those using metal oxide semiconductors, experience saturation at high gas concentrations, leading to inaccurate readings due to their narrow dynamic range and non-linear response mechanisms.
Innovation Solution
A sensor system that applies electrical stimuli at a single excitation frequency to a sensing material, with a modifier assembly changing the electrical impedance of the sensing element to adjust the linearity of the electrical signal, allowing for improved sensitivity and dynamic range across various gas concentrations without altering the excitation frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional resistance measurement is used for MOS sensing material, then the sensor can detect gas concentration, but the response saturates at high concentrations leading to false readings
Solution Approach 1:
The patent changes the measurement parameter from resistance to impedance by applying AC electrical stimuli at specific excitation frequencies. This parameter change enables the sensor to operate in a frequency domain where the power law saturation effect is avoided, allowing accurate measurements across a broader gas concentration range from low to high concentrations.
Solution Approach 2:
The patent introduces dynamic measurement by applying AC electrical stimuli at varying excitation frequencies rather than using static DC resistance measurement. The sensor system dynamically adjusts the excitation frequency to optimize the impedance response, enabling the sensing element to maintain sensitivity across different gas concentration levels without saturation.
2Adaptability or versatility
If MOS materials are used for gas sensing, then broad applications for gas alarms are achieved, but the sensor response follows power law with saturation at high concentrations
Solution Approach 1:
The patent replaces the conventional DC resistance measurement mechanism with AC impedance measurement mechanism. By substituting the measurement approach from time-domain resistance to frequency-domain impedance, the system eliminates the power law saturation behavior while maintaining the broad applicability of MOS sensing materials for various gas detection applications.
Solution Approach 2:
The patent makes the sensing system universal by enabling it to accurately measure gas concentrations across the entire range from low to high levels using a single MOS sensing element. The impedance-based measurement approach allows the same sensor to function effectively in diverse application scenarios without being limited by concentration-dependent saturation effects.
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 enhances the sensor's ability to accurately measure a broad range of gas concentrations with increased sensitivity, maintaining similar sensitivity at low, medium, and high concentrations, and extends the dynamic range of gas measurements with a single sensor.
Implementation Method 1
A second electrical signal is received from the sensing element that is representative of an impedance response of the sensing material
Implementation Method 2
A linearity of the first electrical signal received from the sensing element is changed by changing an electrical impedance of the sensing element
Data Source
AI summary
A sensor system includes a sensing element that includes a sensing material and electrodes configured to apply a first electrical stimuli to the sensing material at an electrical excitation frequency, a modifier assembly including one or more circuits configured to change an electrical impedance of the sensing element, and one or more processors configured to control the modifier assembly. Responsive to exposure of gas to the sensing element, the one or more processors change a linearity of a first electrical signal received from the sensing element by changing the electrical impedance of the sensing element and applying a second electrical stimuli to the sensing material at the electrical excitation frequency.