Gas Sensor Acoustic Resonance Low Optical Power
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Solution Overview
Problem
Conventional photoacoustic gas sensors are not robust and require high optical power, making them inefficient and inconvenient for gas detection, especially with MEMS-based systems.
Innovation Solution
A gas sensor using an intensity modulatable light source, such as an LED or laser diode, with a detection cell designed as an acoustic resonator, where the light source's modulation frequency differs from the resonant frequency of the detection cell by less than 0.5 times, allowing for low-energy, robust, and cost-effective gas concentration determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional photoacoustic gas sensors use intensity modulated radiation with broadband light sources, then gas concentration measurement is achieved, but high optical power is required and the system is not robust
Solution Approach 1:
The patent applies acoustic resonance (mechanical vibration) in the detection cell to amplify pressure and density fluctuations caused by gas absorption. By tuning the modulation frequency of the light source to match the resonant frequency of the detection cell, the system achieves enhanced measurement sensitivity with significantly reduced optical power requirements compared to conventional photoacoustic sensors.
Solution Approach 2:
The patent changes the operating parameters by using intensity modulatable light sources (LEDs or laser diodes) with modulation frequencies specifically tuned to match the acoustic resonant frequency of the detection cell. This parameter optimization allows efficient energy transfer and amplification of the photoacoustic signal, reducing the need for high optical power.
2Measurement precision
If mechanical choppers are applied for modulating intensity with thermal radiators, then gas detection is achieved, but the system is not robust
Solution Approach 1:
The patent replaces mechanical choppers with electronically modulated light sources (LEDs or laser diodes). The intensity modulation is achieved through electronic control of the light source driver circuit, eliminating moving mechanical parts and thereby significantly improving system robustness and reliability while maintaining the ability to perform gas detection.
3Volume of moving object
If detection cell is formed in multi-ply substrate by MEMS method, then compact structure is achieved, but manufacturing complexity increases
Solution Approach 1:
The patent segments the detection system into distinct functional components: a separately manufacturable detection cell (which can be formed by various methods including but not limited to MEMS) and the optical/electronic components. This segmentation allows flexibility in manufacturing approach and simplifies the overall production process while maintaining compact dimensions.
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 solution enables efficient and robust gas concentration measurement with reduced optical power requirements, utilizing LEDs or laser diodes and acoustic resonator design to amplify pressure and density fluctuations for accurate gas detection.
Implementation Method 1
gas molecules are excited to execute mechanical (e.g., molecular) oscillations by intensity modulated radiation of an emitter unit, for example, a light source
Implementation Method 2
an essentially gas-sealed detection cell having an optical window, wherein the detection cell forms an acoustic resonator
Data Source
AI summary
A gas sensor for determining a concentration of at least one gas in a gas mixture includes: at least one intensity modulatable light source; a measuring section, into which the gas mixture to be investigated can be allowed to flow; and an essentially gas-sealed detection cell, wherein the gas sensor is embodied such that light emitted from the light source is radiated into a measuring section, wherein the intensity of the emitted light is modulated with a modulation frequency, which differs from the resonant frequency of a mode of the acoustic resonance of the detection cell by less than 0.5 times, especially less than 0.25 times, the half-width of the mode. Further, a method for determining the concentration of the at least one gas in the gas mixture uses the gas sensor.