New, invisible nano-fibers conduct electricity, repel dirt

Jun 28, 2007
New, invisible nano-fibers conduct electricity, repel dirt
A scanning electron microscope image of plastic fibers grown on a sheet of transparent film. Ohio State University researchers have invented a technique for carpeting a surface with tiny plastic fibers. The fibers can be made to attract or repel water and oil. Credit: Image courtesy of Ohio State University

Tiny plastic fibers could be the key to some diverse technologies in the future -- including self-cleaning surfaces, transparent electronics, and biomedical tools that manipulate strands of DNA.

In the June issue of the journal Nature Nanotechnology, Ohio State University researchers describe how they created surfaces that, seen with the eye, look as flat and transparent as a sheet of glass. But seen up close, the surfaces are actually carpeted with tiny fibers.

New, invisible nano-fibers conduct electricity, repel dirt
A drop of water balances perfectly on a plastic surface invented by researchers at Ohio State University. The surface is covered with microscopic fibers, and can be made to attract or repel water. The surface shown here is water repellant, so the drop can't spread out along the surface; instead, it retains its spherical shape. Credit: Photo by Jo McCulty, courtesy of Ohio State University

The patent-pending technology involves a method for growing a bed of fibers of a specific length, and using chemical treatments to tailor the fibers' properties, explained Arthur J. Epstein, Distinguished University Professor of chemistry and physics and director of the university's Institute for Magnetic and Electronic Polymers.

"One of the good things about working with these polymers is that you're able to structure them in many different ways," Epstein said. "Plus, we found that we can coat almost any surface with these fibers."

For this study, the scientists grew fibers of different heights and diameters, and were able to modify the fibers' molecular structures by exposing them to different chemicals.

They devised one treatment that made the fibers attract water, and another that made the fibers repel water. They found they could also make the surfaces attract or repel oil. Depending on what polymer they start with, the fibers can also be made to conduct electricity.

The ability to tailor the properties of the fibers opens the surface to many different applications, he said.

Since dirt, water, and oil don't stick to the repellant fibers, windows coated with them would stay cleaner longer.

In contrast, the attracting fibers would make a good anti-fog coating, because they pull at water droplets and cause them to spread out flat on the surface.

They devised one treatment that made the fibers attract water, and another that made the fibers repel water. They found they could also make the surfaces attract or repel oil. Depending on what polymer they start with, the fibers can also be made to conduct electricity.

What's more, researchers found that the attracting surface does the same thing to coiled-up strands of DNA. When they put droplets of water containing DNA on the fibers, the strands uncoiled and hung suspended from the fibers like clotheslines.

Epstein said scientists could use the fibers as a platform to study how DNA interacts with other molecules. They could also use the spread-out DNA to build new nanostructures.

"We're very excited about where this kind of development can take us," he added.

Epstein's research centers on polymers that conduct electricity, and light up or change color. Depending on the choice of polymer, the nano-fiber surface can also conduct electricity. The researchers were able to use the surface to charge an organic light-emitting device -- a find that could pave the way for transparent plastic electronics.

Finally, they also showed that the fibers could be used to control the flow of water in microfluidic devices --- a specialty of study co-author L. James Lee, professor of chemical and biomolecular engineering and head of Ohio State's Center for Affordable Nanoengineering of Polymeric Biomedical Devices.

Lee and Epstein are advisors to former graduate student Nan-Rong Chiou, who developed the technology to earn his doctorate. He is now a visiting scholar at the university. Other co-authors on the paper included former doctoral students Chunmeng Lu and Jingjiao Guan.

The technology is a merger of two different chemical processes for growing polymer molecules: one grows tiny dots of polymer "seeds" on a flat surface, and the other grows vertical fibers out from the top of the seeds. The fibers grow until the scientists cut off the chemical reaction, forming a carpet of uniform height.

The university will license the technology, and Epstein and his colleagues are looking for new applications for it.

Aside from anti-fog windows, self-cleaning windows, and organic LEDs, Chiou said that he foresees the surfaces working in glucose sensors, gene therapy devices, artificial muscles, field emission displays, and electromagnetic interference shielding.

Source: Ohio State University

Explore further: Making graphene in your kitchen

add to favorites email to friend print save as pdf

Related Stories

Scientists explore one of Earth's deepest ocean trenches

Apr 11, 2014

What lives in the deepest part of the ocean—the abyss? A team of researchers funded by the National Science Foundation (NSF) will use the world's only full-ocean-depth, hybrid, remotely-operated vehicle, ...

Bending the light with a tiny chip

Mar 10, 2014

(Phys.org) —Imagine that you are in a meeting with coworkers or at a gathering of friends. You pull out your cell phone to show a presentation or a video on YouTube. But you don't use the tiny screen; your ...

Engineers create ultra-sensitive artificial skin

Jul 30, 2012

(Phys.org) -- Engineers from South Korea and the United States working together have developed a new type of artificial skin that is less complex, cheaper to make and more sensitive than other electronic sensors ...

Recommended for you

Making graphene in your kitchen

1 minute ago

Graphene has been touted as a wonder material—the world's thinnest substance, but super-strong. Now scientists say it is so easy to make you could produce some in your kitchen.

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

(Phys.org) —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

Easter morning delivery for space station

Space station astronauts got a special Easter treat: a cargo ship full of supplies. The shipment arrived Sunday morning via the SpaceX company's Dragon cargo capsule.