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Professor Frank Ko, left, and Professor Thomas Hahn stand in front of their electrospinning device at the Multi-Functional Composite lab at UCLA.

Researchers at UCLA have taken an old method from a common spider and spun it into a new idea for creating stronger materials.

The idea was to copy the approach spiders use in spinning a web and to apply this to a method for creating stronger nano-sized fiber materials, according to Thomas Hahn, mechanical and aerospace engineering professor at UCLA’s Henry Samueli School of Engineering and Applied Science, and Frank Ko, a materials engineering professor from Drexel University.

For the last seven months, the two professors worked at the Multi-Functional Composite Laboratory at UCLA, developing the “electrospinning” technique, which spins a web of fibers using an electrostatic force.

The process starts with a polymer solution mixed with nano-sized particles to form a composite solution. The particles are so small that they can only be seen through high-powered microscopes.

“In general, nanotechnology and nano-sized particles allow us to get down to the quantum level,” Ko said. “This effect describes how performance can be enhanced exponentially, where chemical reactions can occur much more quickly, electrons move faster, and heat is conducted much better.”

“And because of the fineness of the material, and the cohesion between the atoms, the material is much stronger,” he added.

The fibers Hahn and Ko are spinning measure approximately 100 nanometers in diameter. A typical strand of human DNA measures just 1.5 nanometers in diameter.

With the solution mixed with nano-sized particles in place, Hahn and Ko connect it to a positive voltage supply to create an electric field, which induces an electrostatic force that pulls the solution out of its container.

Once the solution is drawn out of its container, it passes through an open space and is drawn toward a “collector plate,” where it solidifies into fiber form.

“You can’t see (the fiber), because it’s on a nano scale,” Ko said. “But if you put your hand (in the electric field), you can feel a nanofiber in your hand, so you know it’s there.”

Once the fibers solidify onto the collection plate, researchers then analyze them for their strength, conductivity and overall functionality using a scanning electron microscope.

Analyzing the samples and their content is a job left up to Russell Luoh, one of Hahn’s graduate students working with the device.

“We are discovering that depending on the composite material used, they react differently with the polymer, and that’s something we are trying to understand more,” Hahn said.

While Hahn focuses on mixing nano-particles into the polymer solution to add different functions, Ko’s expertise lies with the nanocomposites in fiber form.

Ko believes these nanofibers will have many applications for electronic, biological and structural components. Their experiments using nanofibers as a conductive layer have already yielded better results than some of the most state-of-the-art materials for electronic components, according to Ko.

He believes nanofibers will also play a role in biomedical engineering.

“You can use this material as a sensor or use it for regeneration of tissues, and it’s compatible to nature’s (nano-sized) scale, so you can grow cells and implant it in your skin, muscles or even nerves,” Ko said. “The biological implication is really an area of great interest for both of us.”

These nanofibers can also be applied to structural engineering and building techniques, from tennis rackets to military aircraft.

Hahn, who has worked with the U.S. Navy and Air Force for many years, believes that the aerospace industry has many applications for strong and lightweight materials, including military aircraft and satellites.

The whole project has been a learning process for both Hahn and Ko, who are experts in working with composite materials and have known each other for over twenty years.

Part of this learning process was the interdisciplinary nature of their work.

“Suddenly, we find that we have to know a lot of chemistry and electrical engineering,” Ko said. “One thing about nano is you have to work with many groups with good cooperation.”

One such group is led by chemistry professor Richard Kaner, who was responsible for supplying the researchers with the nano-particles used in testing the device.

“A lot of tests still have to be done, but this is extremely exciting,” Ko said. “In industry, they look at this data and they are very interested, and we need to start working with industry to scale this up. But it’s still a long way between where we are now and covering the wing of an airplane.”

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