Smart gas sensor detects chemicals more sensitive

According to the website of the American Association for the Advancement of Science (USA) on May 2 (Beijing time), researchers at the University of Michigan are developing a portable, adjustable, two-dimensional micro gas chromatograph that can recognize and detect chemical gas components and is more sensitive and intelligent. Detection of explosives, chemical weapons, volatile gases, but also through the patient's breathing diagnosis of the disease, to detect whether the mine is safe. The instrument is also very energy-efficient and has great advantages for mine operations and medical facilities in remote areas. Related papers were recently published in the journal Analytical Chemistry.

Fan Xudong, a professor at the school’s Department of Biomedical Engineering, explained that the various components of the volatile gas are like a cloud of tiny clouds that overlap. Before testing, separate them. In a volatile mixture, identify each The ingredients are very difficult. At present, most sensors pass mixed gas through two test tubes in sequence. The first test tube is coated with a layer of polymer, which will slow down the speed of the heavier molecules and roughly separate the gases by weight.

Sensors being developed by researchers are more effective at separating various chemical components. Let the gas pass through the first tube first to get preliminary clues, then use a pump and compressor to collect the gas from the first tube and send it regularly to the second tube for a second test. The second tube is coated with a layer of polar polymer, one end with a positive charge and the other with a negative charge, which slows down the speed of those polarized gas molecules. Unpolarized molecules can pass faster. Based on this information, researchers can identify the chemical composition of the gas. Add a decision device to the system and connect the computer. Through the computer, you can see the whole process of gradual separation of various chemical components.

Under the guidance of the decision-making device, the compressor can only operate again after a small cloud has completely passed. This method allows the same kind of molecules to gather and analyze the data easier. The second detection process can also add a rotating test tube to allow faster gas passage. At this point, the decision device also acts as an “operator”. When a test tube is “busy”, the gas is sent to another test tube. This will not stop the gas from entering the first test tube and entering the second test tube.

The second test tube can also be customized, using different coatings made of various lengths of test tubes to separate special gases, such as a special molecular "hot line", which can detect certain special molecules. Fan Xudong said: "If we suspect that there are chemical weapons leaked in a certain place, we will send a batch of this special molecular 'hotline' in the past and we will be able to identify these ingredients very sensitively."

At present, the research team has demonstrated that the new device can distribute gas between the two test tubes. The smart sensor can recognize chemical gases containing 20 different components and the composition of the mixture released by plants. (Reporter Chang Lijun)

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