Secrets of nanohair adhesion un-peeled by UA polymer scientists

Nov 19, 2010
Fine hairs on the soles of gecko feet allow the lizards to climb vertical surfaces with ease. UA polymer researchers have discovered a synthetic glue (carbon nanotubes) with nearly four times the adhesion power of gecko hairs. Now the scientists reveal why the mimic version offers its remarkable staying power.

Not long after Dr. Ali Dhinojwala, chairman of The University of Akron Department of Polymer Science, unpeeled the secret (fine, clingy hairs) behind the remarkable adhesion of gecko feet, he and fellow researchers came up with a synthetic replica: carbon nanotubes. Now, five years after that initial discovery, the basis of the success of these nanotubes is published in the Oct. 12, 2010, issue of the American Chemical Society’s Nano Letters.

While the story of nanotubes is one of success, not all carbon nanotubes are equal, nor is the individual adhesion performance of each strand, according to Dhinojwala. Although Dhinojwala and UA science graduate student Liehui Ge determined that these 8-nanometer-diameter carbon hairs — each 2,000 times smaller than the diameter of a human hair — adhere powerfully to glass and similar substrates, they furthered their research to learn why some strands have a firmer grip than others.

This video is not supported by your browser at this time.

Getting a grip on adhesion

Findings by the UA scientists, in collaboration with Lijie Ci and Anubha Goyal, researchers with the Department of Mechanical Engineering and Materials Science at Rice University; Rachel Shi, UA Research Experience for Undergraduates (REU) intern; and L. Mahadevan, professor of applied mathematics and professor of organismic and evolutionary biology at Harvard University, reveal that the softer the nanotube, the greater its adhesion.

Using a combination of mechanics, electrical resistance and scanning electron microscopy (SEM) to study the contact between hairs of a large number of vertically aligned carbon nanotubes with glass or silicon substrates, the researchers found that soft nanotubes clasp and curve when pressure is applied, contributing to their adhesive strength.

“We found out that the diameter of the tubes is an important parameter for adhesion because we have to balance the adhesion and bending rigidity of the tubes,” Ge says. “Also, if you apply a high pressure, the tubes bend and buckle and make a larger contact area with the surface, which is the reason for higher .”

The dry adhesive, unlike liquid glue counterparts, promises successful use in extreme atmospheric and temperature conditions and in other applications that present challenges.

“The carbon nanotube-based gecko adhesives are going to open up opportunities to using these materials on robots, to climb vertical walls, and could actually be used in outer space (vacuum condition) because these materials stick without any liquid glue,” Dhinojwala says.

Explore further: Thinnest feasible nano-membrane produced

Provided by University of Akron

5 /5 (1 vote)

Related Stories

Sticky gecko feet: The role of temperature and humidity

May 14, 2008

A team of five University of Akron researchers has published the paper, “Sticky gecko feet: the role of temperature and humidity” in PLoS ONE, an open-access, online journal for peer-reviewed scientific and medical research.

Carbon nanotubes twice as strong as once thought

Sep 15, 2010

Carbon nanotubes -- those tiny particles poised to revolutionize electronics, medicine, and other areas — are much bigger in the strength department than anyone ever thought, scientists are reporting.

Nanotubes find niche in electric switches

Mar 10, 2009

New research from Rice University and the University of Oulu in Oulu, Finland, finds that carbon nanotubes could significantly improve the performance of electrical commutators that are common in electric ...

Recommended for you

Thinnest feasible nano-membrane produced

Apr 17, 2014

A new nano-membrane made out of the 'super material' graphene is extremely light and breathable. Not only can this open the door to a new generation of functional waterproof clothing, but also to ultra-rapid filtration. The ...

Wiring up carbon-based electronics

Apr 17, 2014

Carbon-based nanostructures such as nanotubes, graphene sheets, and nanoribbons are unique building blocks showing versatile nanomechanical and nanoelectronic properties. These materials which are ordered ...

Making 'bucky-balls' in spin-out's sights

Apr 16, 2014

( —A new Oxford spin-out firm is targeting the difficult challenge of manufacturing fullerenes, known as 'bucky-balls' because of their spherical shape, a type of carbon nanomaterial which, like ...

User comments : 0

More news stories

'Exotic' material is like a switch when super thin

( —Ever-shrinking electronic devices could get down to atomic dimensions with the help of transition metal oxides, a class of materials that seems to have it all: superconductivity, magnetoresistance ...

Innovative strategy to facilitate organ repair

A significant breakthrough could revolutionize surgical practice and regenerative medicine. A team led by Ludwik Leibler from the Laboratoire Matière Molle et Chimie (CNRS/ESPCI Paris Tech) and Didier Letourneur ...

Treating depression in Parkinson's patients

A group of scientists from the University of Kentucky College of Medicine and the Sanders-Brown Center on Aging has found interesting new information in a study on depression and neuropsychological function in Parkinson's ...