Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

MIT closes in on bionic speed

09.11.2005


See caption below


See caption below


Theory could result in faster artificial muscles

Robots, both large and micro, can potentially go wherever it’s too hot, cold, dangerous, small or remote for people to perform any number of important tasks, from repairing leaking water mains to stitching blood vessels together.

Now MIT researchers, led by Professor Sidney Yip, have proposed a new theory that might eliminate one obstacle to those goals - the limited speed and control of the "artificial muscles" that perform such tasks. Currently, robotic muscles move 100 times slower than ours. But engineers using the Yip lab’s new theory could boost those speeds - making robotic muscles 1,000 times faster than human muscles - with virtually no extra energy demands and the added bonus of a simpler design. This study appears in the Nov. 4 issue of the journal Physical Review Letters.



In this case, a robotic muscle refers to a device that can be activated to perform a task, like a sprinkler activated by pulling a fire alarm lever, explains Yip, a professor of nuclear engineering and materials science and engineering.

In the past few years, engineers have made the artificial muscles that actuate, or drive, robotic devices from conjugated polymers. "Conjugated polymers are also called conducting polymers because they can carry an electric current, just like a metal wire," says Xi Lin, a postdoctoral associate in Yip’s lab. (Conventional polymers like rubber and plastic are insulators and do not conduct electricity.)

Conjugated polymers can actuate on command if charges can be sent to specific locations in the polymer chain in the form of "solitons" (charge density waves). A soliton, short for solitary wave, is "like an ocean wave that can travel long distances without breaking up," Yip adds. (See figures.) Solitons are highly mobile charge carriers that exist because of the special nature (the one-dimensional chain character) of the polymer.

Scientists already knew that solitons enabled the conducting polymers to conduct electricity. Lin’s work attempts to explain how these materials can activate devices. This study is useful because until now, scientists, hampered by not knowing the mechanism, have been making conducting polymers in a roundabout way, by bathing (doping) the materials with ions that expand the volume of the polymer. That expansion was thought to give the polymers their strength, but it also makes them heavy and slow.

Lin discovered that adding the ions is unnecessary, because theoretically, shining a light of a particular frequency on the conducting polymer can activate the soliton. Without the extra weight of the added ions, the polymers could bend and flex much more quickly. And that rapid-fire motion gives rise to the high-speed actuation, that is, the ability to activate a device.

To arrive at these conclusions, Lin worked from fundamental principles to understand the physical mechanisms governing conjugated polymers, rather than using experimental data to develop hypotheses about how they worked. He started with Schrödinger’s equation, a hallmark of quantum mechanics that describes how a single electron behaves (its wave function). But solving the problem of how a long chain of electrons behaves was another matter, requiring long and complex analyses.

This research was funded by Honda R&D Co. and the Defense Advanced Research Projects Agency/Office of Naval Research. Yip and Lin’s collaborators on the work are Professor Ju Li at Ohio State University and Professor Elisabeth Smela at the University of Maryland.

In Figure 1, a soliton (blob with red and blue stripes) moves along a conducting polymer chain (aqua and yellow for hydrogen and carbon). The soliton blob causes a localized bend in the chain. The traditional way to make polymer actuate is to dope the material with an ion such as sodium, represented by the red dot. New MIT research has suggested another way, shown in figure 2, is to shine light of a specific frequency (h‡), on the conducting polymer. The polymer in figure 2 is a chain (neutral charge, green) that is naturally curved before exposure. The effect of light (h‡ frequency) is to create positive charges (red) in a localized area. The positive charges enhance the chemical bonding between the polymer’s units and straighten out the curved chain in that area. (This straightening occurs where the red and blue striped lobe appeared in Figure 1. The lobe can move along the polymer chain rapidly.) Figures courtesy Yip lab, MIT

Elizabeth Thomson | EurekAlert!
Further information:
http://www.mit.edu

More articles from Physics and Astronomy:

nachricht X-ray photoelectron spectroscopy under real ambient pressure conditions
28.06.2017 | National Institutes of Natural Sciences

nachricht New photoacoustic technique detects gases at parts-per-quadrillion level
28.06.2017 | Brown 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: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Supersensitive through quantum entanglement

28.06.2017 | Physics and Astronomy

X-ray photoelectron spectroscopy under real ambient pressure conditions

28.06.2017 | Physics and Astronomy

Mice provide insight into genetics of autism spectrum disorders

28.06.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>