Single-walled carbon nanotubes enable strain sensing

Sensor Review

ISSN: 0260-2288

Article publication date: 1 September 2004



(2004), "Single-walled carbon nanotubes enable strain sensing", Sensor Review, Vol. 24 No. 3.



Emerald Group Publishing Limited

Copyright © 2004, Emerald Group Publishing Limited

Single-walled carbon nanotubes enable strain sensing

Single-walled carbon nanotubes enable strain sensing

One of the hottest fields of nanotechnological research involves the study of carbon nanotubes. Ever since they were discovered, they have found numerous applications in varied areas of engineering and science. Recently, researchers at Rice University in Houston, Texas, found a potential application for single-walled carbon nanotubes (SWNT) as strain sensors.

The scientists have discovered changes in the electrical properties of carbon nanotubes when subjected to strains. This property has been tapped in the development of a carbon nanotube film sensor that could be used to sense strain on a macroscale. It is expected that strain sensors based on carbon nanotubes could potentially address the limitations of directionality associated with existing macroscale strain-sensing systems.

Existing strain sensors, apart from being directional, are also separate from the material or structure that is being monitored. Recently, there has been an increased push towards developing new sensors that can be embedded into the system. The properties of SWNTs facilitate their use as fibres in composites for producing high strength materials.

Carbon nanotube films have many useful properties, among which is their isotropic nature. This occurs because of the random orientation of the SWNT bundles during fabrication. Such films have demonstrated the ability to effect a linear change in voltage across the film, when subjected to tensile and compressive stresses. This voltage change could be measured by a movable four-point probe attached to the film.

The potential applications for such films are only limited by imagination. Many critical surface stress measurements such as the stress on an aircraft's skin could be measured with ease. Traditional measurement would use methods like Raman Spectroscopy, which is constrained by bulky hardware in field applications. The researchers feel that in such applications, carbon nanotube films could be the easier alternative. The sensing film could potentially be integrated into the material (composites) and serve both sensory and structural functions.

The researchers have claimed that experimental testing of the sensor film has demonstrated a nearly linear relationship between the measured parameter and voltage change. The researchers are upbeat about the results and hope to find applications in multidirectional and multiple location strain sensors on a macroscale.

The work has been published in the recent issue of the journal Nanotechnology.

For further details, contact: Satish Nagarajaiah, Associate Professor, Dynamical Systems Group, Computer and Information Technology Institute, Rice University, 6100 Main Street Houston, TX 77005. Tel: 713-348-6207; Fax: 713-348-5268; E-mail:

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