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Honolulu, Hawaii, United States, 2006/09/26 - A group od Danish and UK researchers found that self-assembled organic nanofibers, which are otherwise totally impossible to remove from any normal surface, can be lifted straight off from a nanotube forest.
The ubiquitous static friction (stiction) and adhesion forces comprise a major obstacle in the manipulation of matter at the nanoscale. In order to realize the potential of nanotubes and nanowires as components in electronic devices or other microsystems, methods for reliable pick-and-place assembly must be established. A major obstacle here is the delicate balance required between the adhesion forces acting between the object to be manipulated, and the surface and the manipulation tool, respectively. A group od Danish and UK researchers found that self-assembled organic nanofibers, which are otherwise totally impossible to remove from any normal surface, can be lifted straight off from a nanotube forest. It means that the notorious stickiness of even the most soft and fragile materials, which immobilizes them and prevent handling, is a problem that now can be solved.
Kjetil Gjerde, a Ph.D. student at the Department of Micro- and Nanotechnology at the Technical University of Denmark, explains the new findings to Nanowerk: "A forest of carbon nanotubes has an incredible low adhesion to most materials. The key is the extremely small effective surface area. Any object suspended on a nanotube forest will in a sense hardly touch it."
Gjerde is first author of a recent paper, titled "Carbon nanotube forests: a non-stick workbench for nanomanipulation", that was published in the September 11, 2006 online edition of Nanotechnology. Also involved in this work were researchers from the Nanointegration project at Technical University of Denmark, the nanotube research at Cambridge University in the UK, and the nano research at the University of Southern Denmark.
In general, adhesive and frictional forces depend on the effective surface area in contact between two objects. Uniquely, when using the nanotube forest, only the nanotube tips are in contact with the object, minimizing the effective contact area greatly and hence lowering the total stiction and adhesion forces. The ability of each individual carbon nanotube (CNT) to bend in any direction as a response to an applied force makes the nanotube forest mechanically compliant, expanding the possibilities for three-dimensional manipulation compared to existing techniques.
Read the full article on the Nanowerk website.
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By Michael Berger, Copyright 2006 Nanowerk LLC.