Featured Research

from universities, journals, and other organizations

Ultrasonically propelled nanorods spin dizzyingly fast

Date:
July 22, 2014
Source:
National Institute of Standards and Technology (NIST)
Summary:
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 have clocked their speed -- and it's fast. At up to 150,000 revolutions per minute, ten times faster than any nanorotor 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

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.

Related Articles


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.


Story Source:

The above story is based on materials provided by National Institute of Standards and Technology (NIST). Note: Materials may be edited for content and length.


Journal Reference:

  1. Andrew L. Balk, Lamar O. Mair, Pramod P. Mathai, Paul N. Patrone, Wei Wang, Suzanne Ahmed, Thomas E. Mallouk, J. Alexander Liddle, Samuel M. Stavis. Kilohertz Rotation of Nanorods Propelled by Ultrasound, Traced by Microvortex Advection of Nanoparticles. ACS Nano, 2014; 140716010052004 DOI: 10.1021/nn502753x

Cite This Page:

National Institute of Standards and Technology (NIST). "Ultrasonically propelled nanorods spin dizzyingly fast." ScienceDaily. ScienceDaily, 22 July 2014. <www.sciencedaily.com/releases/2014/07/140722130740.htm>.
National Institute of Standards and Technology (NIST). (2014, July 22). Ultrasonically propelled nanorods spin dizzyingly fast. ScienceDaily. Retrieved December 20, 2014 from www.sciencedaily.com/releases/2014/07/140722130740.htm
National Institute of Standards and Technology (NIST). "Ultrasonically propelled nanorods spin dizzyingly fast." ScienceDaily. www.sciencedaily.com/releases/2014/07/140722130740.htm (accessed December 20, 2014).

Share This


More From ScienceDaily



More Matter & Energy News

Saturday, December 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Building Google Into Cars

Building Google Into Cars

Reuters - Business Video Online (Dec. 19, 2014) Google's next Android version could become the standard that'll power your vehicle's entertainment and navigation features, Reuters has learned. Fred Katayama reports. Video provided by Reuters
Powered by NewsLook.com
AP Review: Nikon D750 and GoPro Hero 4

AP Review: Nikon D750 and GoPro Hero 4

AP (Dec. 19, 2014) What to buy an experienced photographer or video shooter? There is some strong gear on the market from Nikon and GoPro. The AP's Ron Harris takes a closer look. (Dec. 19) Video provided by AP
Powered by NewsLook.com
Double-Amputee Becomes First To Move Two Prosthetic Arms With His Mind

Double-Amputee Becomes First To Move Two Prosthetic Arms With His Mind

Buzz60 (Dec. 19, 2014) A double-amputee makes history by becoming the first person to wear and operate two prosthetic arms using only his mind. Jen Markham has the story. Video provided by Buzz60
Powered by NewsLook.com
Navy Unveils Robot Fish

Navy Unveils Robot Fish

Reuters - Light News Video Online (Dec. 18, 2014) The U.S. Navy unveils an underwater device that mimics the movement of a fish. Tara Cleary reports. Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins