Frogs feet and nano hopes

What is common to the feet of a tree frog and scotch tape?

Both are sticky. Both are marvels—one of nature, the other of human ingenuity.

In comparison to nature’s design, human science comes off poorly. Scotch tape is only good for light objects, such as paper, and you can use scotch tape only once. Now, think of the tree frog. Its glue is super-sticky: a frog’s tiny, sticky foot pads can support its entire weight when it is upside down. And the frog’s stickiness lasts a lifetime.

In 2007, in a study published in the journal Science, scientists from the Indian Institute of Technology-Kanpur (IIT-K) revealed they had created a new sticky tape. Not only was the tape reusable, it was about 30 times stronger than normal. Conventional tape cracks when pulled off. So, the IIT researchers mimicked a frog’s footpad—it has surface patterns, laced underneath with vessels, glands and blood vessels—by running air- or oil-filled micro-channels through a soft, elastic material.

It was a clever trick. But it was a laboratory demonstration. No one knew how to get the new sticky tape to a production line. Now, the same team of IIT-K scientists, led by Ashutosh Sharma, a winner of the Infosys Science Prize for 2010, says its science has advanced enough to manufacture the frog-inspired scotch-tape. The scientists have filed a global patent for their technique, and their secrets will be revealed later this month in a paper due to be published in Langmuir, the journal of the American Chemical Society.

This advance isn’t only about a better scotch tape. It reveals the myriad possibilities of the arcane, emerging world of nanotechnology and its endless applications, some of which are the research interests of Sharma, institute chair professor and principal investigator of the Centre of Nanosciences at IIT-K, and a scientist with many awards and a rare ability to see the big picture.

The underlying theme of Sharma’s work is the power of self-organization, getting something simple to change to something more complex. Stretch a string, says Sharma. You give it energy to be taut. Let go. It collapses to its original shapelessness, a low-energy state that everything aspires to. Sharma and his team try to understand, predict and control the ability of things to self-organize, so new and more efficient materials can be created.

How do you get things to self-organize? “About 99% of things are unstable,” says Sharma. “They are not happy the way they are. They want to change.”

The key to this change lies on the surface of things (appropriately called surface science). We are now dealing with nano science, of things that are invisible, and the manipulation of their atoms. Nanotechnology creates new products and new ways of doing things by controlling the components of matter, of things.

One of the new paradigms of manufacturing in nanotechnology is self-assembly, the next step from self-organization. The idea is simple, the execution is not: Persuade the atoms and molecules of things a thousand times smaller than the width of a human hair to assemble themselves into a tiny, useful object. This kind of manufacturing uses quieter, gentler tools; for instance, an electric field or temperature change, instead of a power drill.

In the nano world, materials do not alone determine properties. Size is important as well. We know the colour of gold—or so we think. But at the atomic level, gold has no fixed colour. It looks and behaves differently depending on its size. At different sizes, particles of materials can be persuaded to behave as insulators, metals or semiconductors. They can exhibit electronic, mechanical, chemical or magnetic properties.

The applications of such nanotechnology are not all high-tech, but they can impact products and processes in a quietly disruptive way. Among the biggest real-world users of nanotechnology are pharmaceutical and cosmetics companies. Globally, the beauty products company L’Oreal probably holds more nanotech patents than anyone else, controlling atoms and molecules to produce better sunscreens and skin lotions.

Sharma’s team focuses on carbon-based manufacturing as its area of interest. (Plastics and silicon are well known to industry. Carbon—the building block of human beings—is relatively new.) The applications include: Micro batteries for new electronics; carbon nano capsules for sharper, smarter drug delivery; nano lenses for better imaging; new materials to clean up land or water. The last area of research has led Sharma to collaborative agreements with Thermax, an energy and environmental solutions company, and the Tata Research Development and Design Centre, the organization that deployed bacteria-killing nano silver particles to create the path-breaking water-filter Swach.

Sharma says he imparts his scientific work on the power of self-assembling with a beyond-the-laboratory approach he calls 3M—mechanics, materials and manufacturing. This is how the super-sticky tape will, hopefully, be as useful as it is clever.

Samar Halarnkar is editor-at-large, the Hindustan Times and Mint. This is a fortnightly column that explores the cutting edge of science and technology. Comments are welcome at frontiermail@livemint.com

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