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Technology Opportunity: Application of Carbon Nanotube Hold-off Voltage for Determining Gas Composition
June 4, 2014


NASA has developed a lightweight, small sensor that detects one or more inert gas components and measures gas concentration with accuracy comparable to conventional sensors. Few sensors are available to detect inert gases. Conventional inert gas analysis tools primarily rely upon infrared (IR) spectroscopy, mass spectroscopy (MS) and/or thermal conductivity measurements. Thermal conductivity sensors are available for fixed and portable instruments, but this conventional technique is not suitable for measuring extremely low levels of a gas (e.g., less than 1 percent by volume resolution), and the technique has difficulties when the target gas has a thermal conductivity close to that of a background gas.

The new technology uses variable voltages, applied to an exposed end of a carbon nanotube immersed in a gas mixture for a variable time interval, to estimate gas composition. It distinguishes between a gas component discharge that occurs substantially instantaneously and a discharge in the same gas component that occurs after a substantial time delay. The sensor is able to detect and identify the presence of one, two or more gas components, some or all of which may be relatively inert (e.g., Ne, Ar, Xe, Kr, CO, etc.). It also provides an estimate of the concentration of at least one gas component. Use of one or more carbon nanotube contacts may allow a more precise determination of discharge voltage holdoff than would be available where a larger diameter electrical contact is used.


• Use constant non-pulse hold-off voltages
• Can be combined with other gas discharge methods
• Measures extremely low levels of gases
• Accurate
• Low cost
• Light weight
• Consumes small amounts of power
• Can be automated


Technology Detail

This technology is a method and system for identifying chemical composition of a single-component or multiple-component gas, using a discharge holdoff mechanism. A voltage difference, V, between two spaced-apart electrodes is brought to a selected value and held, the hoIdoff time interval, Δt(V;ho), required before gas discharge is measured, and the associated electrical current or cumulative electrical charge is measured. As the voltage difference V increases, the time interval length Δt(V;ho) decreases monotonically. Particular voltage values, V∞ and Vₒ, correspond to initial appearance of discharge (Δt ≈∞) and prompt discharge (Δt ≈O). The values V∞ and Vₒ and the rate of decrease of Δt(V;ho) and/or the rate of increase of current or cumulative charge with increasing V are characteristic of one or more gas components present.

Commercial Applications

• Space exploration
• Oil and Gas industry
• Terrestrial environment
• Air monitoring in buildings, tunnels, and mines
• Public safety
• Fire detection
• Automobile industry
• Healthcare
• Leak detection


This technology has been patented (U.S. Patent 7,529,633). Reference: ARC-15506-1.

Licensing and Partnering Opportunities

NASA’s Technology Transfer Program seeks to transfer this technology out of NASA’s space program to benefit U.S. industry. NASA invites companies to inquire about licensing possibilities for this technology for commercial applications.

For More Information

If you would like more information about this technology, please contact:
Technology Partnerships Division
NASA Ames Research Center

Printable Fact Sheet: Application of Carbon Nanotube Hold-off Voltage for Determining Gas Composition


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Application of Carbon Nanotube Hold-off Voltage for Determining Gas Composition
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Page Last Updated: June 26th, 2014
Page Editor: Yael Kovo