Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

NIST shows ultrasonically propelled nanorods spin dizzyingly fast

23.07.2014

Vibrate a solution of rod-shaped metal nanoparticles in water with ultrasound and they'll spin around their long axes like tiny drill bits. Why?

No one yet knows exactly. But researchers at the National Institute of Standards and Technology (NIST) have clocked their speed—and it's fast. At up to 150,000 revolutions per minute, these nanomotors rotate 10 times faster than any nanoscale object submerged in liquid ever reported.


In this image, a nanoparticle traces the microvortical flow around a nanorod rotating at up to 150,000 RPM propelled by ultrasound.

Credit: Balk/NIST

The discovery of this dizzying rate has opened up the possibility that they could be used not only for moving around inside the body—the impetus for the research—but also for high-speed machining and mixing.

Scientists have been studying how to make nanomotors move around in liquids for the past several years. A group at Penn State looking for a biologically friendly way to propel nanomotors first observed that metal nanorods were moving and rotating in response to ultrasound in 2012. Another group at the University of California San Diego then directed the metal rods' forward motion using a magnetic field. The Penn State group then demonstrated that these nanomotors could be propelled inside of a cancer cell.

But no one knew why or how fast the nanomotors were spinning. The latter being a measurement problem, researchers at NIST worked with the Penn State group to solve it.

"If nanomotors are to be used in a biological environment, then it is important to understand how they interact with the liquid and objects around them," says NIST project leader Samuel Stavis. "We used nanoparticles to trace the flow of water around the nanomotors, and we used that measurement to infer their rate of rotation. We found that the nanomotors were spinning surprisingly rapidly."

The NIST team clocked the nanomotors' rotation by mixing the 2-micrometer-long, 300-nanometer-wide gold rods with 400-nanometer-diameter polystyrene beads in water and putting them between glass and silicon plates with a speaker-type shaker beneath. They then vibrated the shaker at an ultrasonic tone of 3 megahertz—much too high for you or your dog to hear—and watched the motors and beads move.

As the motors rotate in water, they create a vortex around them. Beads that get close get swept up by the vortex and swirl around the rods. By measuring how far the beads are from the rods and how fast they move, the group was able to work out how quickly the motors were spinning—with an important caveat.

"The size of the nanorods is important in our measurements" says NIST physicist Andrew Balk. "We found that even small variations in the rod's dimensions cause large measurement uncertainties, so they need to be fabricated as uniformly as possible for future studies and applications."

According to the researchers, the speed of the nanomotors' rotation seems to be independent of their forward motion. Being able to control the "speed and feed" of the nanomotors independently would open up the possibility that they could be used as rotary tools for machining and mixing.

Future avenues of research include trying to discover exactly why the motors rotate and how the vortex around the rods affects their interactions with each other.

###

*A.L. Balk, L.O. Mair, P.P. Mathai, P.N. Patrone, W.Wang, S. Ahmed, T.E. Mallouk, J.A. Liddle and S.M. Stavis. Kilohertz rotation of nanorods propelled by ultrasound, traced by microvortex advection of nanoparticles. ACS Nano, Articles ASAP (As Soon As Publishable) Publication Date (Web): July 14, 2014. DOI: 10.1021/nn502753x.

Mark Esser | Eurek Alert!
Further information:
http://www.nist.gov

Further reports about: NIST Nanoparticles Standards mixing motors nanoparticles spinning

More articles from Physics and Astronomy:

nachricht Introducing the disposable laser
04.05.2016 | American Institute of Physics

nachricht New fabrication and thermo-optical tuning of whispering gallery microlasers
04.05.2016 | Okinawa Institute of Science and Technology (OIST) Graduate University

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Nuclear Pores Captured on Film

Using an ultra fast-scanning atomic force microscope, a team of researchers from the University of Basel has filmed “living” nuclear pore complexes at work for the first time. Nuclear pores are molecular machines that control the traffic entering or exiting the cell nucleus. In their article published in Nature Nanotechnology, the researchers explain how the passage of unwanted molecules is prevented by rapidly moving molecular “tentacles” inside the pore.

Using high-speed AFM, Roderick Lim, Argovia Professor at the Biozentrum and the Swiss Nanoscience Institute of the University of Basel, has not only directly...

Im Focus: 2+1 is Not Always 3 - In the microworld unity is not always strength

If a person pushes a broken-down car alone, there is a certain effect. If another person helps, the result is the sum of their efforts. If two micro-particles are pushing another microparticle, however, the resulting effect may not necessarily be the sum their efforts. A recent study published in Nature Communications, measured this odd effect that scientists call “many body.”

In the microscopic world, where the modern miniaturized machines at the new frontiers of technology operate, as long as we are in the presence of two...

Im Focus: Tiny microbots that can clean up water

Researchers from the Max Planck Institute Stuttgart have developed self-propelled tiny ‘microbots’ that can remove lead or organic pollution from contaminated water.

Working with colleagues in Barcelona and Singapore, Samuel Sánchez’s group used graphene oxide to make their microscale motors, which are able to adsorb lead...

Im Focus: ORNL researchers discover new state of water molecule

Neutron scattering and computational modeling have revealed unique and unexpected behavior of water molecules under extreme confinement that is unmatched by any known gas, liquid or solid states.

In a paper published in Physical Review Letters, researchers at the Department of Energy's Oak Ridge National Laboratory describe a new tunneling state of...

Im Focus: Bionic Lightweight Design researchers of the Alfred Wegener Institute at Hannover Messe 2016

Honeycomb structures as the basic building block for industrial applications presented using holo pyramid

Researchers of the Alfred Wegener Institute (AWI) will introduce their latest developments in the field of bionic lightweight design at Hannover Messe from 25...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

The “AC21 International Forum 2016” is About to Begin

27.04.2016 | Event News

Soft switching combines efficiency and improved electro-magnetic compatibility

15.04.2016 | Event News

Grid-Supportive Buildings Give Boost to Renewable Energy Integration

12.04.2016 | Event News

 
Latest News

New fabrication and thermo-optical tuning of whispering gallery microlasers

04.05.2016 | Physics and Astronomy

Introducing the disposable laser

04.05.2016 | Physics and Astronomy

A new vortex identification method for 3-D complex flow

04.05.2016 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>