Subscribe to our free daily newsletters
. 24/7 Space News .




Subscribe to our free daily newsletters



ROBO SPACE
Nylon fibers made to flex like muscles
by Staff Writers
Boston MA (SPX) Nov 25, 2016


This image shows the fabrication steps from raw circular filament to a fully functional bending artificial muscle. The bottom filament is a raw circular filament. Researchers press the filament using a rolling mill (the second sample from the bottom). Next, they add a mask in the middle of the surface (the third sample from the bottom). Then, they add the conductive ink (the second sample from the top). Finally, they remove the mask after the ink is dried (the sample on the top). Image courtesy Felice Frankel and Seyed Mohammad Mirvakili.

Artificial muscles - materials that contract and expand somewhat like muscle fibers do - can have many applications, from robotics to components in the automobile and aviation industries. Now, MIT researchers have come up with one of the simplest and lowest-cost systems yet for developing such "muscles," in which a material reproduces some of the bending motions that natural muscle tissues perform.

The key ingredient, cheap and ubiquitous, is ordinary nylon fiber. The new approach to harnessing this basic synthetic fiber material lies in shaping and heating the fibers in a particular way, which is described in a new paper in the journal Advanced Materials by Seyed Mirvakili, a doctoral candidate, and Ian Hunter, the George N. Hatsopoulos Professor in the Department of Mechanical Engineering.

Previously, researchers had come up with the basic principle of using twisted coils of nylon filament to mimic basic linear muscle activity. They showed that for a given size and weight, such devices could extend and retract further, and store and release more energy, than natural muscles. But bending motions, such as those of human fingers and limbs, proved more challenging and had not yet been achieved in a simple and inexpensive system until the new work at MIT.

There are some existing materials that can be used to produce these kinds of bending motions, which could be useful for some biomedical devices or tactile displays. However, those tend to use "exotic materials to do the job, and they are very expensive and very difficult to make," Mirvakili says. For example, carbon nanotube yarns can provide great longevity (more than a million linear contraction cycles) but are still too expensive for widespread use, and shape-memory alloys provide a strong contracting pull but have a poor cycle life (fewer than 1,000 cycles).

Cheap and simple
The new nylon-based system, by contrast, uses cheap material and a simple manufacturing process, and demonstrates very good cycling longevity. It all comes down to how the nylon fibers are shaped.

Some polymer fiber materials, including highly oriented nylon, have an unusual property: When heated, "they shrink in length but expand in diameter," Mirvakili says, and this property has been harnessed to make some linear actuator devices. But to turn that linear shrinking motion into bending typically requires a mechanism such as a pulley and a takeup reel, adding extra size, complexity, and expense. The MIT team's advance was to directly harness the motion without requiring extra mechanical parts.

One of the limitations on linear actuators made from such materials is that after being heated to trigger the contraction, they take some time to cool back down. "The cooling rate can be a limiting factor," Mirvakili says.

"But I realized it could be used to an advantage." Selectively heating one side of the fiber, he says, causes that side to begin contracting faster than the heat can penetrate to the other side, and thus can produce a bending motion in the fiber. "You need a combination of these properties," he says: "high strain [the pull of the shrinking motion] and low thermal conductivity."

To make this system work effectively as an artificial muscle, the fiber's cross-section needs to be carefully shaped. The team used ordinary nylon fishing line to start with, and compressed it to change its cross-section from round to rectangular or square. Then, selectively heating one side caused the fiber to bend in that direction. Changing the direction of the heating could also produce more complex motions; in their lab tests, the team used this heating technique to get the fibers to move in circles and figure-eights, and much more complex patterns of movement could easily be achieved, they say.

Various heat sources can be used on the fibers, including electric resistance heating, chemical reactions, or a laser beam that shines on the filament. For some of their tests, the researchers used a special conductive paint applied to the fibers and held in place by a resin binder; when a voltage was applied to the material, it selectively heated the portion of the fiber directly below the paint, causing the fiber to bend that way.

Long-lived material
The researchers have demonstrated that the material can maintain its performance after at least 100,000 bending cycles, and can bend and retract at a speed of at least 17 cycles per second.

Hunter suggests that ultimately, applications for such fibers might include clothes that contract to adjust snugly to the contours of an individual body, drastically reducing the number of different sizes a manufacturer would need to produce, while improving the comfort and fit. Or, the fibers might be used in shoes that would tighten themselves when put on or adjust their stiffness and shape during each stride.

The system may also allow for self-adjusting catheters or other biomedical devices. And in the longer run, it could even lead to mechanical systems such as vehicle exterior panels that adjust their aerodynamic shape to adapt to changes in speed and wind conditions, or automatic tracking systems for solar panels that would use excess heat generated by the panels themselves to keep the panels aimed at the sun.


Comment on this article using your Disqus, Facebook, Google or Twitter login.


Thanks for being here;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.

SpaceDaily Contributor
$5 Billed Once


credit card or paypal
SpaceDaily Monthly Supporter
$5 Billed Monthly


paypal only

.


Related Links
Massachusetts Institute of Technology
All about the robots on Earth and beyond!






Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle

Previous Report
ROBO SPACE
New AI algorithm taught by humans learns beyond its training
Toronto, Canada (SPX) Nov 18, 2016
"Hey Siri, how's my hair?" Your smartphone may soon be able to give you an honest answer, thanks to a new machine learning algorithm designed by U of T Engineering researchers Parham Aarabi and Wenzhi Guo. The team designed an algorithm that learns directly from human instructions, rather than an existing set of examples, and outperformed conventional methods of training neural networks by ... read more


ROBO SPACE
China sets patent filing record: UN

ESA astronaut Thomas Pesquet arrives at the International Space Station

Moscow to mull building Russian orbital station in Spring 2017

New crews announced for Space Station

ROBO SPACE
Star One D1 arrives for heavy-lift Ariane 5 in Dec with 2 SSL-built satellites

SLS propulsion system goes into Marshall stand ahead of big test series

Predictive modeling for NASA's Entry, Descent, and Landing Missions

Arianespace doubles its Galileo delivery capacity with Ariane 5

ROBO SPACE
ESA's new Mars orbiter prepares for first science

NASA field test focuses on science of lava terrains, like Early Mars

Can we grow potatoes on Mars

Dutch firm unveils concept space suit for Mars explorers

ROBO SPACE
Material and plant samples retrieved from space experiments

Chinese astronauts return to earth after longest mission

China completes longest manned space mission yet

Chinese astronauts accept 1st earth-space interview

ROBO SPACE
Charyk helped chart the course of satellite communications

Intelsat and Intelsat General support hurricane Matthew recovery efforts

Boeing to consolidate defense and space sites

Can India beat China at its game with common satellite for South Asia

ROBO SPACE
NASA microthrusters achieve success on ESA's LISA Pathfinder

Sweden orders new laser simulators from Saab

Calculations predict unexpected disorder in the surface of polar materials

New clues emerge in 30-year-old superconductor mystery

ROBO SPACE
Scientists from the IAC discover a nearby 'superearth'

Earth-bound instrument analyzes light from planets circling distant stars

Protoplanetary Discs Being Shaped by Newborn Planets

Scientists unveil latest exoplanet-hunter CHARIS

ROBO SPACE
New analysis adds to support for a subsurface ocean on Pluto

Pluto follows its cold, cold heart

New Analysis Supports Subsurface Ocean on Pluto

Mystery solved behind birth of Saturn's rings




Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News






The content herein, unless otherwise known to be public domain, are Copyright 1995-2017 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement