Understanding of actuator properties of carbon nanotubes bring micro machines closer

Imagine machines smaller than microscopic in size working around us, in us and for us. Imagine them seeking out diseases, cleaning the environment and making the world a better place. Just as a car is a combination of a whole series of separate items, engine, suspension, wheels, electronics, chassis, etc, nanomachines too need to be constructed from a range of components.

One such component is a type of actuator to open and close things, to absorb shock, lift or lower loads and provide other forms of linear movement. It is known that forms of carbon nanotubes can function as actuators, but thanks to some new research we have a better understanding of what they do and how well they do it.

A Fraunhofer Techologie-Entwicklungsgruppe based research team have published a paper looking at an actuation measurement set-up constructed to perform electromechanical characterization of bucky papers. Bucky papers are sheets of carbon nanotubes obtained via filtration process. The research paper has been published in a special edition of the open access journal, AZoJono*. This special edition of AZoJono features a number of papers from DESYGN-IT, the project seeking to secure Europe as the international scientific leader in the design, synthesis, growth, characterisation and application of nanotubes, nanowires and nanotube arrays for industrial technology.

The researchers, Urszula Kosidlo, Daniel Georg Weis, Klaus Hying, Mohammad H. Haque and Ivica Kolaric, constructed a special measurement device and performed their tests in liquid electrolyte to allow the build up of the electrochemical double-layer, which is necessary for the actuation of carbon nanotubes. The measurements are performed with focus on the out-of-plane strain and stress generated by the structure of interest.

The device they designed was found to be useful for characterising electromechanical properties of bucky paper. Using their device, they were able to determine the dependence on applied voltage, electrolyte used as well as performance under additional load applied on the sample. They also concluded that to gain a better understanding of the actuation mechanism of bucky paper, galvanodynamic tests, current/charge controlled should be performed. The device that was used in this investigation is also suitable for this application.

The article is available to view in full in AZoJono at http://www.azonano.com/Details.asp?ArticleID=2043