Nano-liquids promise next-gen mobile displays

Liquids embedded with nanoparticles show enhanced performance and stability

Robert Jaques, vnunet.com 21 Feb 2008

A combination of nanoparticles and liquids could pave the way for new miniature camera lenses, mobile phone displays and other microscale fluidic devices, according to US scientists.

Researchers at Rensselaer Polytechnic Institute have demonstrated that liquids embedded with nanoparticles show enhanced performance and stability when exposed to electric fields.

"This study may open up a new vista for using nanofluids in microscale and nanoscale actuator device applications," said Theodorian Borca-Tasciuc, a professor of mechanical engineering at Rensselaer, who led the research project.

Professor Borca-Tasciuc explained that the manipulation of small volumes of liquid is critical for fluidic digital display devices, optical devices and microelectromechanical applications such as lab-on-chip analysis systems.

Most research into such systems has been conducted with regular liquids, but not nanofluids which are embedded with different nanoparticles.

The team placed droplets of water-based solutions containing bismuth telluride nanoparticles onto a Teflon-coated silicon wafer.

When an electric field was applied to the droplet, the researchers observed a strong change in the angle at which the droplet contacted the wafer.

This change was much higher than that observed in liquids without the nanoparticles when tested under the same conditions.

"You use the same electrical field, but you get more change in shape with the nanofluid. We know the nanoparticles are critical in this process because without them the effect is much less strong," said Professor Borca-Tasciuc.

The scientist went on to point out that the ability to easily change the contact angle of droplets of nanofluids has potential applications for efficiently moving liquids in microsystems, creating new methods of focusing lenses in miniature cameras or cooling computer chips.

Professor Borca-Tasciuc said that his investigations were fostered by a strong interdisciplinary collaboration with Rensselaer Materials Science and Engineering professor Ganapathiraman Ramanath.

"At first, we were curious to see what would happen if we introduced charged nanostructures, such as the ones we synthesise for exploring new cooling strategies in nanodevices, to the process of liquid wetting," said Professor Ramanath.

"But what started as a single one-off experiment has now mushroomed into an exciting new research topic and expanded the scope of our collaboration."

The research article, titled Electrowetting on Dielectric-Actuation of Microdroplets of Aqueous Bismuth Telluride Nanoparticle Suspensions, was published in a recent issue of Nanotechnology.

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