Suspended Gas Sensor Phase Shift Detection
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Solution Overview
Problem
Existing gas concentration sensors are sensitive to parasitic phenomena and have complex constructions, making them less robust and more challenging to manufacture, while also being larger in size, which limits their integration and application in nanostructures.
Innovation Solution
A gas concentration sensor with a suspended structure that uses dynamic polarization and phase shift measurement between the excitation signal and response signal, reducing sensitivity to parasitic phenomena and allowing for smaller, more robust, and high-resolution devices with reduced thermal response time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If amplitude measurement is used to determine gas concentration, then the measurement can be performed with simple equipment, but the device becomes sensitive to parasitic phenomena such as adsorption effects
Solution Approach 1:
The patent changes the measurement parameter from amplitude to phase shift. By measuring the phase difference between excitation and response signals instead of amplitude variations, the system achieves immunity to parasitic phenomena while maintaining measurement capability. This parameter transformation resolves the contradiction between simple equipment and reliable measurement.
2Volume of moving object
If the sensor size is reduced to facilitate integration, then the number of areas of application increases, but the surface/volume ratio increases making the device more sensitive to surface phenomena
Solution Approach 1:
The patent measures phase shift rather than amplitude, which fundamentally changes the measurement parameter to one that is insensitive to surface effects. This allows the sensor to be miniaturized without increasing sensitivity to parasitic phenomena, as the phase-based measurement does not depend on surface area.
3Measurement precision
If a support plate with heating element is used, then thermal exchange measurement can be performed, but the device becomes complex to manufacture
Solution Approach 1:
The patent combines the heating function and the measurement function into a single suspended structure. The same structure that is heated also serves as the temperature sensor through its electrical resistance, eliminating the need for separate heating elements and support plates. This merging simplifies manufacturing while maintaining measurement precision.
Solution Approach 2:
The suspended structure performs multiple functions: it serves as the heating element, the temperature sensor, and the thermal exchange measurement device all in one. This multi-functionality reduces the number of components needed and simplifies the manufacturing process while maintaining the ability to perform precise thermal exchange measurements.
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 sensor provides more reliable and less sensitive measurements to parasitic effects, achieving high resolution and enabling the production of small, high-performance detectors compatible with microelectronics and CMOS technologies, suitable for use in gas chromatography applications.
Implementation Method 1
means for dynamic polarization of said suspended structure forming means of dynamic excitation... Under the effect of the dynamic excitation signal, the suspended structure is heated
Implementation Method 2
The variation of this phase shift is a function of the thermal conductivity of the gas and the thermal capacity of the gas
Implementation Method 3
The variation of this phase shift is a function of the thermal conductivity of the gas and the thermal capacity of the gas
Implementation Method 4
The voltage variation is measured across the heated support plate to determine the variation in electrical resistance which depends on the temperature of the support plate
Data Source
Figure 1~5
Figure 3A~3C
Figure 4A~4D
AI summary
A concentration sensor for at least one given gas comprising at least one structure suspended (2) relative to a support, said suspended structure (2) being made of an electrically conductive material and said structure having a low thermal response time, means for polarizing said suspended element (2) and means for measuring (8) the variation of the electrical voltage across the terminals of the suspended structure (2), the polarization means (6) being formed by an alternating current source whose intensity heats the suspended structure (2) and whose frequency causes a phase shift between a signal from the polarization means and a signal measured by the measurement means, and means for determining a variation of the phase shift due to a variation in gas concentration and means for determining the variation in the concentration of said gas from the phase variation.