Featured Research

from universities, journals, and other organizations

A layer of tiny grains can slow sound waves

Date:
August 6, 2013
Source:
Massachusetts Institute of Technology
Summary:
Researchers say the findings could lead to a new way of controlling frequencies in electronic devices such as cellphones, but with components that are only a fraction the size of those currently used for that function. On a larger scale, it could lead to new types of blast-shielding material for use in combat or by public-safety personnel or equipment.

Photograph of a two-dimensional array of microspheres adhered to a substrate.
Credit: MIT/Photo courtesy of Tian Gan

In some ways, granular material -- such as a pile of sand -- can behave much like a crystal, with its close-packed grains mimicking the precise, orderly arrangement of crystalline atoms. Now researchers at MIT have pushed that similarity to a new limit, creating two-dimensional arrays of micrograins that can funnel acoustic waves, much as specially designed crystals can control the passage of light or other waves.

The researchers say the findings could lead to a new way of controlling frequencies in electronic devices such as cellphones, but with components that are only a fraction the size of those currently used for that function. On a larger scale, it could lead to new types of blast-shielding material for use in combat or by public-safety personnel or equipment.

A paper on the research appears in the journal Physical Review Letters, written by Nicholas Fang, the Brit and Alex d'Arbeloff Career Development Associate Professor in Engineering Design; Nicholas Boechler, a former MIT postdoc now at the University of Washington; and four co-authors.

Research on the properties of granular materials -- collections of small grains, such as sand or tiny glass beads -- has become "a rich and rapidly developing field," the researchers write. But most such research has focused on the properties of sand-sized particles, about a millimeter across, Fang says. The new work is the first to examine the very different properties of particles that are about one-thousandth that size, or one micrometer across, whose properties were expected to be "qualitatively different."

In their experiments, the team used a single layer of microspheres to guide and slow sound waves (known as surface acoustic waves, or SAWs) traveling across a surface, Fang says. The researchers used ideas they had previously applied in research on controlling light waves, he says, which involved the use of photonic crystals.

SAWs are widely used in electronic devices such as cellphones, Fang says, "like clocks that give a single frequency signal … to synchronize different chips or parts of a chip." But with the new system, "we can shrink the device size" needed for processing SAWs, he says. Present-day oscillators for SAWs are relatively bulky, Fang says, but the use of a 2-D granular material to guide and slow the waves could allow such devices to be only one-sixth their present size, he estimates.

What's more, the 2-D nature of this system could allow it to be fabricated right on a chip, along with the necessary control circuits and other components. Today's oscillators, by contrast, are typically separate devices placed next to the chip array that controls them, Fang says -- so in cases where small size is important, the new work has the potential to allow for even smaller electronic devices.

The system could potentially also be used to develop new kinds of sensors, such as microbalances capable of measuring tiny changes in weight, he says.

The same principle could also lead to a new kind of blast-shielding material, Fang suggests. If acoustic waves -- such as the intense shock waves from an explosion -- hit the two-dimensional material at a right angle, much of their energy can be converted to surface waves that travel sideways out of the material. A sandwich of many layers of such material might provide substantial protection from a blast in a lightweight, wearable form, though such applications will likely require substantial further research, Fang says.

In addition to Fang and Boechler, the research team included graduate students Jeff Eliason and Anshuman Kumar; research fellow Alex Maznev; and professor of chemistry Keith Nelson. The work was supported by the Defense Threat Reduction Agency and the National Science Foundation.


Story Source:

The above story is based on materials provided by Massachusetts Institute of Technology. The original article was written by David L. Chandler. Note: Materials may be edited for content and length.


Cite This Page:

Massachusetts Institute of Technology. "A layer of tiny grains can slow sound waves." ScienceDaily. ScienceDaily, 6 August 2013. <www.sciencedaily.com/releases/2013/08/130806132936.htm>.
Massachusetts Institute of Technology. (2013, August 6). A layer of tiny grains can slow sound waves. ScienceDaily. Retrieved October 22, 2014 from www.sciencedaily.com/releases/2013/08/130806132936.htm
Massachusetts Institute of Technology. "A layer of tiny grains can slow sound waves." ScienceDaily. www.sciencedaily.com/releases/2013/08/130806132936.htm (accessed October 22, 2014).

Share This



More Matter & Energy News

Wednesday, October 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Thanks, Marty McFly! Hoverboards Could Be Coming In 2015

Thanks, Marty McFly! Hoverboards Could Be Coming In 2015

Newsy (Oct. 21, 2014) If you've ever watched "Back to the Future Part II" and wanted to get your hands on a hoverboard, well, you might soon be in luck. Video provided by Newsy
Powered by NewsLook.com
Robots to Fly Planes Where Humans Can't

Robots to Fly Planes Where Humans Can't

Reuters - Innovations Video Online (Oct. 21, 2014) Researchers in South Korea are developing a robotic pilot that could potentially replace humans in the cockpit. Unlike drones and autopilot programs which are configured for specific aircraft, the robots' humanoid design will allow it to fly any type of plane with no additional sensors. Ben Gruber reports. Video provided by Reuters
Powered by NewsLook.com
Graphene Paint Offers Rust-Free Future

Graphene Paint Offers Rust-Free Future

Reuters - Innovations Video Online (Oct. 21, 2014) British scientists have developed a prototype graphene paint that can make coatings which are resistant to liquids, gases, and chemicals. The team says the paint could have a variety of uses, from stopping ships rusting to keeping food fresher for longer. Jim Drury reports. Video provided by Reuters
Powered by NewsLook.com
China Airlines Swanky New Plane

China Airlines Swanky New Plane

Buzz60 (Oct. 21, 2014) China Airlines debuted their new Boeing 777, and it's more like a swanky hotel bar than an airplane. Enjoy high-tea, a coffee bar, and a full service bar with cocktails and spirits, and lie-flat in your reclining seats. Sean Dowling (@SeanDowlingTV) has the details. Video provided by Buzz60
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