Featured Research

from universities, journals, and other organizations

Surprising behavior of tiny 'artificial muscles' explained

Date:
April 29, 2010
Source:
National Institute of Standards and Technology (NIST)
Summary:
Using neutron beams and atomic-force microscopes, a team of researchers may have resolved a 10-year-old question about an exotic class of "artificial muscles" -- how do they work? Their results could influence the design of future specialized robotic tools.

Still image from a video showing the IPMC actuator bending under an applied electrical voltage. As the polarity of the 3-volt potential is switched, the actuator bends back and forth.
Credit: R. Moore/Virginia Polytechnic Institute and State University

Using neutron beams and atomic-force microscopes, a team of university researchers working with the National Institute of Standards and Technology (NIST) may have resolved a 10-year-old question about an exotic class of "artificial muscles" -- how do they work? Their results* could influence the design of future specialized robotic tools.

Related Articles


These "artificial muscles," first demonstrated in the early 1990s, are "ionic polymer metal composite" (IPMC) actuators, a thin polymer strip plated on both surfaces with conducting metal. The basic unit of the polymer molecule has a charged component attached to it (hence, "ionic"), and it forms a sort of open, permeable structure that can be soaked with water molecules and oppositely charged ions. A modest electric charge across the metalized surfaces will cause the strip to flex in one direction; an alternating charge will make it wiggle like a fish's tail. But why?

"There has been a lot of debate as to the mechanism of actuation in these kinds of systems," says NIST materials scientist Kirt Page. One possibility was that the electric charge on the metalized faces causes the polymer and the free ions to reorient themselves next to the metal, stretching one side and contracting the other. But using a neutron beam at the NIST Center for Neutron Research (NCNR) to watch an IPMC in action as it wiggled back and forth, the team found something very different. Neutrons are particularly good for mapping the locations of water molecules, and they showed that a major force in the actuator is hydraulics. "The water and ions move to one electrode swelling one side and dehydrating the other, causing that to contract, and it bends in that direction," explains Virginia Tech professor Robert Moore, who directed the research. "Then you flip the potential, the ions come screaming back -- positive ions again moving towards the new negative electrode -- and you can go back and forth."

It happens surprisingly fast, according to Page. "People weren't quite convinced that water could actually move over these distances that quickly," he says, "This paper is the first to show that in fact, this gradient in the water concentration is established almost instantaneously."

A better understanding of just how IPMC actuators work could allow researchers to engineer better materials of this type with improved performance. Current actuators can be small and light-weight, and they can flex over relatively large distances, but the force they can generate is low so these "muscles" are not very strong, according to Moore. They could be used in microfluidic systems as pumps or valves, as tiny robotic grippers in applications where other actuators are impractical or even, says Moore, "as actual artificial muscles in living tissues. I think we're still in the infancy stage of using these. There are still quite a number of details about the mechanism that we need to unlock."


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. Jong Keun Park, Paul J. Jones, Chris Sahagun, Kirt A. Page, Daniel S. Hussey, David L. Jacobson, Sarah E. Morgan, Robert B. Moore. Electrically stimulated gradients in water and counterion concentrations within electroactive polymer actuators. Soft Matter, 2010; 6 (7): 1444 DOI: 10.1039/b922828d

Cite This Page:

National Institute of Standards and Technology (NIST). "Surprising behavior of tiny 'artificial muscles' explained." ScienceDaily. ScienceDaily, 29 April 2010. <www.sciencedaily.com/releases/2010/04/100428121521.htm>.
National Institute of Standards and Technology (NIST). (2010, April 29). Surprising behavior of tiny 'artificial muscles' explained. ScienceDaily. Retrieved November 26, 2014 from www.sciencedaily.com/releases/2010/04/100428121521.htm
National Institute of Standards and Technology (NIST). "Surprising behavior of tiny 'artificial muscles' explained." ScienceDaily. www.sciencedaily.com/releases/2010/04/100428121521.htm (accessed November 26, 2014).

Share This


More From ScienceDaily



More Matter & Energy News

Wednesday, November 26, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

NASA's First 3-D Printer In Space Creates Its First Object

NASA's First 3-D Printer In Space Creates Its First Object

Newsy (Nov. 26, 2014) — The International Space Station is now using a proof-of-concept 3D printer to test additive printing in a weightless, isolated environment. Video provided by Newsy
Powered by NewsLook.com
Bolivian Recycling Initiative Turns Plastic Waste Into School Furniture

Bolivian Recycling Initiative Turns Plastic Waste Into School Furniture

Reuters - Innovations Video Online (Nov. 26, 2014) — Innovative recycling project in La Paz separates city waste and converts plastic garbage into school furniture made from 'plastiwood'. Tara Cleary reports. Video provided by Reuters
Powered by NewsLook.com
Who Will Failed Nuclear Talks Hurt Most?

Who Will Failed Nuclear Talks Hurt Most?

Reuters - Business Video Online (Nov. 25, 2014) — With no immediate prospect of sanctions relief for Iran, and no solid progress in negotiations with the West over the country's nuclear programme, Ciara Lee asks why talks have still not produced results and what a resolution would mean for both parties. Video provided by Reuters
Powered by NewsLook.com
Flying Enthusiast Converts Real-Life Aircraft Cockpit Into Simulator

Flying Enthusiast Converts Real-Life Aircraft Cockpit Into Simulator

Reuters - Innovations Video Online (Nov. 25, 2014) — A virtual flying enthusiast converts parts of a written-off Airbus aircraft into a working flight simulator in his northern Slovenian home. Jim Drury 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