Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

A better understanding of soft artificial muscles

18.11.2019

Research sheds light on the underlying mechanics of soft filaments

Artificial muscles will power the soft robots and wearable devices of the future. But more needs to be understood about the underlying mechanics of these powerful structures in order to design and build new devices.


A filament is clamped at the top end and prestretched by a small amount by applying a downward axial load to the bottom end. The bottom end is then twisted, keeping the axial load on the bottom end constant. After a critical amount of twist is inserted, the filament spontaneously buckles into a loopy.

Credit: Nicholas Charles/Harvard SEAS


A filament is clamped at the top end and prestretched by applying a downward axial load to the bottom end. After a critical amount of twist is inserted, the filament spontaneously buckles into a shape known as a solenoid.

Credit: Nicholas Charles/Harvard SEAS

Now, researchers from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) have uncovered some of the fundamental physical properties of artificial muscle fibers.

"Thin soft filaments that can easily stretch, bend, twist or shear are capable of extreme deformations that lead to knot-like, braid-like or loop-like structures that can store or release energy easily," said L. Mahadevan, the Lola England de Valpine Professor of Applied Mathematics, of Organismic and Evolutionary Biology, and of Physics.

"This has been exploited by a number of experimental groups recently to create prototypical artificial muscle fibers. But how the topology, geometry and mechanics of these slender fibers come together during this process was not completely clear. Our study explains the theoretical principles underlying these shape transformations, and sheds light on the underlying design principles."

"Soft fibers are the basic unit of a muscle and could be used in everything from robotics to smart textiles that can respond to stimuli such as heat or humidity," said Nicholas Charles, a PhD student in Applied Mathematics and first author of the paper.

"The possibilities are endless, if we can understand the system. Our work explains the complex morphology of soft, strongly stretched and twisted fibers and provides guidelines for the best designs."

The research is published in Physical Review Letters.

Soft fibers, or filaments, can be stretched, sheared, bent or twisted. How these different actions interact to form knots, braids, and helices is important to the design of soft actuators. Imagine stretching and twisting a rubber band as tight as you can.

As the twist gets tighter and tighter, part of the band will pop out of the plane and start twisting around itself into a coil or knot. These coils and loops, in the right form, can be harnessed to actuate the knotted fiber.

The researchers found that different levels of stretch and twist result in different types of complex non-planar shapes. They characterized which shapes lead to kinked loops, which to tight coils, and which to a mixture of the two. They found that pre-stretch is important for forming coils, as these shapes are the most stable under stretching, and modeled how such coils can be used to produce mechanical work.

"This research gives us a simple way to predict how soft filaments will respond to twisting and stretching," said Charles.

"Going forward, our work might also be relevant in other situations involving tangled filaments, as in hair curls, polymer dynamics and the dynamics of magnetic field lines in the sun and other stars," said Mahadevan.

###

This research was co-authored by Mattia Gazzola, Assistant Professor of Mechanical Sciences and Engineering at the University of Illinois, and a former member of the group. It was supported in part by the National Science Foundation.

Media Contact

Leah Burrows
lburrows@seas.harvard.edu
617-496-1351

 @hseas

http://www.seas.harvard.edu/ 

Leah Burrows | EurekAlert!
Further information:
https://www.seas.harvard.edu/news/2019/11/better-understanding-soft-artificial-muscles

More articles from Life Sciences:

nachricht Towards better anti-cancer drugs: New insights into CDK8, an important human oncogene
28.01.2020 | Universität Bayreuth

nachricht Unique centromere type discovered in the European dodder
28.01.2020 | Leibniz Institute of Plant Genetics and Crop Plant Research

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Integrate Micro Chips for electronic Skin

Researchers from Dresden and Osaka present the first fully integrated flexible electronics made of magnetic sensors and organic circuits which opens the path towards the development of electronic skin.

Human skin is a fascinating and multifunctional organ with unique properties originating from its flexible and compliant nature. It allows for interfacing with...

Im Focus: Dresden researchers discover resistance mechanism in aggressive cancer

Protease blocks guardian function against uncontrolled cell division

Researchers of the Carl Gustav Carus University Hospital Dresden at the National Center for Tumor Diseases Dresden (NCT/UCC), together with an international...

Im Focus: New roles found for Huntington's disease protein

Crucial role in synapse formation could be new avenue toward treatment

A Duke University research team has identified a new function of a gene called huntingtin, a mutation of which underlies the progressive neurodegenerative...

Im Focus: A new look at 'strange metals'

For years, a new synthesis method has been developed at TU Wien (Vienna) to unlock the secrets of "strange metals". Now a breakthrough has been achieved. The results have been published in "Science".

Superconductors allow electrical current to flow without any resistance - but only below a certain critical temperature. Many materials have to be cooled down...

Im Focus: Programmable nests for cells

KIT researchers develop novel composites of DNA, silica particles, and carbon nanotubes -- Properties can be tailored to various applications

Using DNA, smallest silica particles, and carbon nanotubes, researchers of Karlsruhe Institute of Technology (KIT) developed novel programmable materials....

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

11th Advanced Battery Power Conference, March 24-25, 2020 in Münster/Germany

16.01.2020 | Event News

Laser Colloquium Hydrogen LKH2: fast and reliable fuel cell manufacturing

15.01.2020 | Event News

„Advanced Battery Power“- Conference, Contributions are welcome!

07.01.2020 | Event News

 
Latest News

Towards better anti-cancer drugs: New insights into CDK8, an important human oncogene

28.01.2020 | Life Sciences

Rice lab turns trash into valuable graphene in a flash

28.01.2020 | Materials Sciences

AI can jump-start radiation therapy for cancer patients

28.01.2020 | Health and Medicine

VideoLinks
Science & Research
Overview of more VideoLinks >>>