Editorial Feature

Carbon Nanotubes – Application as Gas Sensors

Cylindrical allotopes of carbon are grouped together as nanotube structures. The importance of carbon nanotubes is starting to become more apparent in the sensor industry. A recent paper by Dr. Katherine A. Mirica et al (2012) describes the structural and functional principle to carbon nanotubes for their application in the detection of harmful gases.

Structurally, carbon nanotubes are long, thin sheets of carbon atoms that can then be shaped into cylindrical forms. The key functional capacity to these carbon nanotubes is their ability to conduct electricity and transmit this wave of energy across their structure, making these nanotubes ideal for the development of highly-sensitive sensor components. The tensile strength and elastic modulus to a carbon nanotube structure allows for a wider range of application for this material in multiple industries.

Carbon Nanotubes

The electrical property to carbon nanostructures is possible due to the symmetry and electronic configuration to this material. The chiral vector to the single-walled carbon nanotube determines the sensitivity of the nanotubes. By having a cylindrical form, carbon nanotubes maintain their level of conductance.

This also means that the electrical transport that takes place along the nanotube structure is enhanced.  During electrical conductance, the single free electron to the carbon atom will travel along the length of the nanostructure in a unidirectional manner.

During exposure to a noxious gas, the gas particle will land on the nanotube structure and change the shape of the nanotube by creating a kink in the shape of this structure, which alters the unidirectional electrical conductance that travels along this material, and this is the main principle to carbon nanotube sensors.

Development of Carbon Nanotube-based Sensors

Chemists at Massachusetts Institute of Technology (MIT) have developed carbon nanotube powder and compressed this material into a new form of pencil lead that can inscribe sensors onto a sheet of paper. The following video focuses on making gas sensors out of carbon nanotubes, which opens application fields for this technology in the food industry, healthcare and homeland security.

Drawing carbon nanotubes on paper at MIT

The current sensor by MIT researchers is designed to detect ammonia gas, which is known to be an industrial toxic chemical. This research opens an exciting new path for customising carbon nanotube-based sensors for a range of volatile gases. A key process in the fabrication of these gas sensors involves dissolving these nanotubes in dichlorobenzene, a solvent used to purify the nanotubes. However, with dichlorobenzene being a chemical carcinogen, this process becomes hazardous and not as accurate.

The research by Katherine A. Mirica et al (2012) tested the pencil containing the carbon nanotube powder by inscribing a line onto a sheet of paper made out of gold particles (the gold sheet delivered the electrode elements to help the electrical conductance move through the inscribed sensors). Application of an electrical current to the carbon nanotube material, a voltage runs through this structure in the presence of gas particles, and as mentioned earlier in this article, if the electrical current is altered it indicates that a gas particle has attached to the carbon structure and changed the flow of electrical energy.

Future research

Carbon nanotubes are sensitive to the surrounding environment because they are structurally capable of absorbing gas particles. For this reason, further research should focus on the thermopower, resistance, and the density of the nanotube complex to provide a deeper understanding of how these parameters can affect the electrical impedance of this material and, furthermore, how ambient conditions could also impact the sensitivity to such carbon-based sensors.

Due to the inherent form and structure of carbon nanotubes, this material has made some impressive progress to say it has a history of less than 20 years in its application. There are various methods to integrating nanotubes with different sensors via processes such as direct-growing, drop-deposition, printing, etc.

As mentioned, the purification method for nanotubes is hazardous and can be unreliable, which makes the production of such sensors on a large scale a costly operation.  Future challenges will aim to find reliable and efficient methods to purify carbon nanotube material without being hazardous to the human and nanostructure.

Sources and Further Reading

  • Wang Y et al. A review of carbon nanotubes-based gas sensors. Journal of Sensors 2009 (2009): 1–24.
  • Bandaru P.R. Electrical properties and applications of carbon nanotubes structures. Journal of Nanoscience and Nanotechnology 2007 (7): 1–29.
  • Mirica K.A., et al. Mechanical drawing of gas sensors on paper. Angewandte Chemie International Edition. 2012 (51).

Disclaimer: The views expressed here are those of the author expressed in their private capacity and do not necessarily represent the views of AZoM.com Limited T/A AZoNetwork the owner and operator of this website. This disclaimer forms part of the Terms and conditions of use of this website.

Citations

Please use one of the following formats to cite this article in your essay, paper or report:

  • APA

    Kaur, Kalwinder. (2019, May 15). Carbon Nanotubes – Application as Gas Sensors. AZoNano. Retrieved on April 14, 2024 from https://www.azonano.com/article.aspx?ArticleID=3107.

  • MLA

    Kaur, Kalwinder. "Carbon Nanotubes – Application as Gas Sensors". AZoNano. 14 April 2024. <https://www.azonano.com/article.aspx?ArticleID=3107>.

  • Chicago

    Kaur, Kalwinder. "Carbon Nanotubes – Application as Gas Sensors". AZoNano. https://www.azonano.com/article.aspx?ArticleID=3107. (accessed April 14, 2024).

  • Harvard

    Kaur, Kalwinder. 2019. Carbon Nanotubes – Application as Gas Sensors. AZoNano, viewed 14 April 2024, https://www.azonano.com/article.aspx?ArticleID=3107.

Tell Us What You Think

Do you have a review, update or anything you would like to add to this article?

Leave your feedback
Your comment type
Submit

While we only use edited and approved content for Azthena answers, it may on occasions provide incorrect responses. Please confirm any data provided with the related suppliers or authors. We do not provide medical advice, if you search for medical information you must always consult a medical professional before acting on any information provided.

Your questions, but not your email details will be shared with OpenAI and retained for 30 days in accordance with their privacy principles.

Please do not ask questions that use sensitive or confidential information.

Read the full Terms & Conditions.