Midea Develops Carbon Nanotube Highly Sensitive Micro Gas Sensor

According to overseas media reports, a joint research group of the Department of Materials Science and Mechanical Engineering of the Rensselaer Polytechnic Institute (United States) recently successfully developed a miniature gas sensor sample using carbon nanotubes, which enables very sensitive quantitative and qualitative analysis. Analyze various gases in the atmosphere.
The sensor structure is very simple. The fabrication method is as follows: First, a multi-walled carbon nanotube (MWCNT) is formed on a silicon dioxide substrate by chemical vapor deposition (CVD). Mainly based on the method developed last year. The MWCNTs have a diameter of about 25-30 nm and a length of about 30 microns. Each MWCNT is arranged at about 50 nm intervals. A gas sensor was completed by applying a 180-μm-thick insulating glass plate at both ends of the MWCNT and then covering it with an aluminum film. The sensor dimensions are: about 20 mm wide, about 20 mm long, and about 700 μm thick.
When a gas sensor was used to measure the surrounding gas composition, the MWCNT terminal was used as the anode (+), and the aluminum film terminal was used as the cathode (-), and a DC voltage was applied. At the MWCNT tip, a very low voltage generates a strong electric field, causing Dielectric Breakdown in the surrounding ionized gas. The test results show that the voltage at which dielectric breakdown occurs is significantly different depending on the type of gas, and qualitative analysis can be performed. The range of gases that can be analyzed is very wide and can even be applied to inert gases such as argon and helium. In addition, although the dielectric breakdown voltage does not depend on the gas concentration, it is known that the generated current value is proportional to the logarithm of the concentration, indicating that the quantitative analysis of the gas can be performed.
The content of this study has been published in the British scientific journal Nature recently published.

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