Golay Cell Gas Detector Using MEMS Microphone on PCB
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Solution Overview
Problem
Gas detection systems based on non-dispersive infrared (NDIR) techniques in the mid-wavelength IR range face challenges with inefficient optical sources, high power consumption, and the expense and complexity of sensitive detectors, particularly in portable and wireless applications.
Innovation Solution
A gas detecting system utilizing a Golay cell with a microphone integrated into a printed circuit board (PCB) substrate, where the gas cavity and microphone work together as a pressure-sensitive unit, leveraging low-cost MEMS microphones for sensitive detection of low-level MWIR radiation, and allowing for low power consumption and compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical power is raised to achieve high signal to noise ratio in MWIR gas detection, then detection sensitivity is improved, but power consumption increases
Solution Approach 1:
The patent replaces traditional thermal detectors or cooled detectors with a MEMS microphone-based acoustic detection system. The microphone detects pressure waves generated by gas absorption of MWIR radiation, converting an optical measurement problem into an acoustic measurement problem. This substitution enables high sensitivity detection with much lower power consumption since MEMS microphones are piezoelectric or capacitive devices requiring minimal power compared to thermal or photodetector systems.
Solution Approach 2:
The patent changes the detection parameter from direct optical intensity measurement to acoustic pressure wave measurement. By detecting the pressure changes caused by gas absorption of MWIR radiation rather than measuring optical power directly, the system achieves high sensitivity with low power consumption. The acoustic signal provides a different physical parameter that is more efficient to measure in the MWIR range.
2Measurement precision
If commercially available MWIR detectors are used to achieve sensitive detection, then detection sensitivity is improved, but system cost increases
Solution Approach 1:
The patent uses inexpensive MEMS microphones, which are mass-produced components from the consumer electronics industry, replacing expensive specialized MWIR detectors. These microphones are cheap, readily available, and can be integrated using standard PCB mounting techniques. The gas cell and optical components are also chosen to be cost-effective, creating an overall low-cost system that achieves comparable sensitivity to expensive commercial detectors.
Solution Approach 2:
The patent extracts the detection function from expensive specialized detectors and implements it using a separate, inexpensive acoustic sensing mechanism. By separating the optical interaction (which occurs in the gas cell) from the detection mechanism (the MEMS microphone), the system can use cheap off-the-shelf components rather than expensive integrated MWIR detector assemblies.
3Measurement precision
If sensitive detectors are used to achieve high performance without raising power consumption, then detection sensitivity is improved, but system complexity increases due to cooling requirements
Solution Approach 1:
The patent replaces complex cooled detectors with simple ambient-temperature MEMS microphones. The acoustic detection mechanism works at room temperature, eliminating the need for cryogenic cooling systems, thermoelectric coolers, or complex thermal management infrastructure. This substitution dramatically reduces system complexity while maintaining detection sensitivity.
4Adaptability or versatility
If NDIR technique with MWIR is used for gas detection, then detection capability for various gases is improved, but portability is reduced due to power consumption
Solution Approach 1:
The patent substitutes the high-power optical detection system with a low-power acoustic detection system using MEMS microphones. This enables portable and potentially wireless gas detection devices because the power consumption is low enough to be supported by batteries. The MWIR optical source can be pulsed or modulated to further reduce average power while maintaining detection capability through the acoustic signal.
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 system achieves sensitive detection of MWIR radiation with low power consumption and cost-effectiveness, reducing interference from environmental factors and enabling compact, portable gas detection for various gases, including flammable, toxic, and environmentally relevant species.
Implementation Method 1
a photoacoustic detector, comprising at least a first chamber (VO) suppliable with a gas to be analyzed, a window for letting modulated and/or pulsed infrared radiation and/or light in the first chamber (VO), a second chamber (V), which constitutes a measuring space with a volume V and which is in communication with the first chamber by way of an aperture provided in a wall of the first chamber, at least one sensor, which is arranged in the wall aperture of the first chamber and arranged to be movable in response to pressure variations produced in the first chamber by absorbed infrared radiation and/or light
Data Source
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AI summary
A gas detecting system (200) comprising: a gas detector device (100) with a Golay cell, the Golay cell comprising: a microphone (102) having a front surface (104) with a sound collecting aperture (108) for receiving sound; a substrate (110); a gas cavity (112) configured to detect a first gas formed in the substrate (110) such that the gas cavity (112) is in gas communication with the sound collecting aperture (108) and the front surface (104) forms a side surface of the gas cavity (112); wherein the gas cavity (112) includes a fill gas comprising at least one or more of hydrogen, argon, nitrogen, krypton, xenon, hydrocarbons, or fluorocarbons; wherein the gas cavity (112) is sealed such that ambient gas cannot enter the gas cavity (112) once it is sealed; a window (114) abutting the substrate (110) to form a side surface of the gas cavity (112), characterized in that the substrate (110) is a printed circuit board, and in that the microphone (102) is electrically connected with the substrate (110); and wherein the gas detector device (100) is replaceable to allow the replacement of the gas detector device (100) from the gas detecting system (200).