The process of extracting natural gas from the earth and transporting it through pipelines releases methane into the atmosphere, which is the main component of natural gas and is a greenhouse gas that affects about 25 times that of global warming, Atmospheric heat is very effective. A new chip-based methane spectrometer, which is smaller than a corner coin, may one day be more efficient and easier to monitor large areas of methane leaks.
Scientists from the IBM Thomas J. Watson Research Center in Yorkshire, New York, have developed a new type of methane spectrometer that is smaller and more costly than the current standard spectrometer. In the Optics High Impact Factor magazine "Optica" The researchers described the new spectrometer in detail and showed that it could detect methane gases as low as one ten thousandth.
Only a small amount of maintenance, with high impact resistance
This spectrometer is based on silicon photonics, which means that it is made of silicon optics, that is used to make computer chip materials.As the use of computer chips can be used the same high-capacity processing methods to manufacture this chip-based Methane spectrometer, so the spectrometer together with the shell and the battery or solar power, if the mass production, the cost may be as low as several hundred dollars.
"With the cost of tens of thousands of commercially available methane detection optical sensors available today, large-capacity machining can make the chip spectrometer a more important value proposition." 'And there's no, "said William Green, head of the IBM research team. Movable parts, and no precise temperature control of the basic requirements of this type of sensor can run for many years and almost no maintenance.
This low-cost, high-quality spectrometer can bring exciting new applications, for example, the IBM team is working with a partner in the oil and gas industry to develop a project that will use a spectrometer to detect methane leaks, Thousands of leaked sites to find and repair the site, you can save the company's time and money.
"In the process of natural gas extraction and distribution, methane may leak into the air when the equipment in the well fails, the valve stuck or the pipe is cracked. 'We are looking for a kind of chip that can be distributed on the wellhead Sensor network, for example, the data collected by these sensors will be processed using IBM 's physical analysis software to automatically determine the location of the leak and the volume of the leak.
Methane is a trace of gas that accounts for less than 1% of the Earth's atmospheric volume. Although the researchers have demonstrated methane testing, the same method can be used to detect the presence of other individual trace gases, which can also be used simultaneously Gas detection.
Our long-term vision is to incorporate these types of sensors into everyday things such as mobile phones or vehicles that can be used to detect contaminants, dangerous levels of carbon monoxide or other molecules of interest. "Because this spectrometer provides a platform for multi - species testing, one day maybe it can also be used for breath analysis for health monitoring," said team member Eric Zhang.
Reduce the spectrometer
This new device uses a method called absorption spectroscopy that requires that the laser is at the wavelength of the only absorption of the molecule under which the laser passes through the air or free space until it reaches the detection The detection of the light reaching the detector results in the amount of molecules in the air that are of interest, and the current concentration can be calculated.
The new system uses a similar approach, but it is not a free space device, but the laser through a narrow silicon waveguide, it is located in the chip above the length of 10 cm long serpentine pattern can be measured in the range of 16 square millimeters. Some light is captured inside the waveguide, and about 25% of the light extends into the outside of the silicon into the air, where it can interact with the trace gas molecules passing through the sensor waveguide. Researchers use near-infrared lasers (1650 nm wavelength ) For methane detection.
In order to improve the sensitivity of the device, the researchers carefully measured and controlled the factors that led to noise and false absorption signals, fine-tuned the design of the spectrometer, and determined the geometric parameters of the waveguide to produce satisfactory results.
Side by side comparison
In order to compare the performance of the new spectrometer with the performance of standard free-space spectrometers, they placed the equipment in the ambient chamber, releasing and controlling the concentration of methane, and the researchers found that the chip-based spectrometer was more than the same level of free-space design Free space sensors are more accurate and reduce the interaction of 75% of the air with the air. In addition, the sensitivity of the chip sensor quantified by the minimum discernibility of the methane concentration and shows that it is superior to the free space spectrometer developed by other laboratories The performance.
Although the silicon photonics system - especially those using refractive index changes in the sensing system, has been previously explored, but the innovative part of our work is to use this type of system to detect low concentrations of methane with very weak absorption signals, and A comprehensive analysis of our sensor chip noise and minimum detection thresholds.
The current version of the spectrometer requires light to flow through the fiber into the chip.However, the researchers are trying to incorporate the light source and the detector onto the chip, which will create an essentially electrical device that does not require fiber connections, unlike the current free space sensor , This type of chip does not require special samples or optical preparation. Next year, they plan to place the spectrometer in a large network including other ready-made sensors for field testing.
"Our work shows that all the knowledge behind silicon photonics, packaging, and component design can be brought into the field of optical sensors, and the bulk mass is, in principle, low-cost sensor processing, and ultimately a new application of the technology." Green said.
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