Dry glue

Dry glue is a method of adhesion based upon the naturally occurring adaptations of the feet of geckos, which allow them to climb sheer surfaces, and even glass walls.

Background

Gecko climbing glass using its natural seta

A gecko can hang on a glass surface using only one toe. This ability of geckos has been attributed to van der Waals force,^[1][2] although a more recent study suggests that water molecules of roughly monolayer thickness (present on virtually all natural surfaces) also play a role.^[3]

Developments

University of Akron and the Rensselaer Polytechnic Institute

Researchers announced in a paper published in the June 18–22, 2007 issue of the Proceedings of the National Academy of Sciences that using this technique they have created a synthetic “gecko tape” with four times the sticking power of a natural gecko foot.^[4] Particularly effective has been a checkerboard carpet of this material, which can be peeled and re-adhered repeatedly without weakening.^[5][6][7] The material is made of columns of carbon nanotubes rooted in pieces of flexible polymer. The nanotubes were grown on a silicon base and then transferred to the polymer to provide a flexible base, similar to a gecko's foot. When dried, the polymer holds the silicon base, which in turn, holds the nanotubes.

Stanford University and Carnegie Mellon University

In 2006, researchers at Stanford University and Carnegie Mellon University developed a gecko-like robot which uses synthetic setae to mount walls.^[8]

Georgia Institute of Technology in Atlanta

On October 9, 2008, the discovery of a new type of dry glue designed to mimic gecko feet was announced. The glue is 10 times stickier than that of the gravity-defying lizards, and three times stickier than other gecko-inspired glues. Liming Dai of the University of Dayton said "It's the stickiest dry glue yet".^[9]

Defense Advanced Research Projects Agency

DARPA (Defense Advanced Research Projects Agency) is also currently working on this technology to enable a soldier to scale a wall at .5 m/s^{[citation needed]}. This project is named Z-Man. Experiments are currently under way to develop nano-adhesives using the van der Waals effect.

References

1. ^ http://www.clemson.edu/newsroom/articles/2009/august/geckos.php5
2. ^ Autumn, Kellar; Sitti, Metin; Liang, Yiching A.; Peattie, Anne M.; Hansen, Wendy R.; Sponberg, Simon; Kenny, Thomas W.; Fearing, Ronald et al. (2002). "Evidence for van der Waals adhesion in gecko setae". Proceedings of the National Academy of Sciences of the USA 99 (19): 12252–12256. Bibcode 2002PNAS...9912252A. doi:10.1073/pnas.192252799. PMC 129431. PMID 12198184. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=129431. 
3. ^ Huber, G.; Mantz, H.; Spolenak, R.; Mecke, K.; Jacobs, K.; Gorb, S. N.; Arzt, E. (2005). "Evidence for capillarity contributions to gecko adhesion from single spatula nanomechanical measurements". Proceedings of the National Academy of Sciences of the USA 102 (45): 16293–16296. Bibcode 2005PNAS..10216293H. doi:10.1073/pnas.0506328102. PMC 1283435. PMID 16260737. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1283435. 
4. ^ Nanotube adhesive sticks better than a gecko's foot, PhysOrg.com retrieved 7 July 2007
5. ^ http://www.nsf.gov/discoveries/disc_summ.jsp?cntn_id=112442&org=NSF
6. ^ Will Knight (2003-06-01). "Gecko-like robot scampers up the wall". New Scientist. Archived from the original on 2007-12-13. http://web.archive.org/web/20071213181425rn_1/www.newscientist.com/article.ns?id=dn3785. Retrieved 2009-05-02  Cites Geim, A. K.; Dubonos, S. V.; Grigorieva, I. V.; Novoselov, K. S.; Zhukov, A. A.; Shapoval, S. Yu. (2003). "Microfabricated adhesive mimicking gecko foot-hair". Nature Materials 2 (7): 461–463. Bibcode 2003NatMa...2..461G. doi:10.1038/nmat917. PMID 12776092. 
7. ^ http://www.uakron.edu/news/articles/uamain_1293.php
8. ^ Gecko-like robot scampers up the wall. New Scientist. 2006-05-23. pp. 29. Archived from the original on 2007-12-16. http://web.archive.org/web/20071216191024/technology.newscientist.com/channel/tech/mg19025526.500.html. Retrieved 2009-05-02 
9. ^ Gecko-like glue is said to be stickiest yet, "reuters.com" 8 October 2008