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 July 31, 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 July 31, 2014).

Share This




More Matter & Energy News

Thursday, July 31, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Britain Testing Driverless Cars on Roadways

Britain Testing Driverless Cars on Roadways

AP (July 30, 2014) British officials said on Wednesday that driverless cars will be tested on roads in as many as three cities in a trial program set to begin in January. Officials said the tests will last up to three years. (July 30) Video provided by AP
Powered by NewsLook.com
7 Ways to Use Toothpaste: Howdini Hacks

7 Ways to Use Toothpaste: Howdini Hacks

Howdini (July 30, 2014) Fresh breath and clean teeth are great, but have you ever thought, "my toothpaste could be doing more". Well, it can! Lots of things! Howdini has 7 new uses for this household staple. Video provided by Howdini
Powered by NewsLook.com
Amid Drought, UCLA Sees Only Water

Amid Drought, UCLA Sees Only Water

AP (July 30, 2014) A ruptured 93-year-old water main left the UCLA campus awash in 8 million gallons of water in the middle of California's worst drought in decades. (July 30) Video provided by AP
Powered by NewsLook.com
Smartphone Powered Paper Plane Debuts at Airshow

Smartphone Powered Paper Plane Debuts at Airshow

AP (July 30, 2014) Smartphone powered paper airplane that was popular on crowdfunding website KickStarter makes its debut at Wisconsin airshow (July 30) Video provided by AP
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:
from the past week

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