Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Miniature Arm Lifts Weights

25.07.2013
Artificial muscle contracts and expands with changes in humidity

A small plastic strip can do “weight training” to effortlessly lifts many times its own weight, driven by cyclic changes in the humidity of the surrounding air.



This strong “artificial arm” is based on the interaction between microgels and a layer of polycations that shrinks as it dries, according to a report presented by Canadian researchers in the journal Angewandte Chemie.

Polymer materials that perform work in response to a chemical or physical stimulus are often called “artificial muscles”.

These are very interesting for a number of applications, including controlling the movements of “gentler” robots. All components of such robots need to be soft and flexible so that they don’t damage delicate objects and can move in tight spaces.

The arm developed by researchers working with Michael J. Serpe at the University of Alberta is constructed in the following way: A strip of a plastic film is coated with chromium and gold, followed by a microgel monolayer.

Microgels are cross-linked polymers that swell up with a solvent such as water to form gel particles with diameters of up to a few micrometers. The Canadian researchers used negatively charged microgels made from poly(N-isopropylacrylamide) and acrylic acid. A solution containing polycations is deposited onto the gel. These act as positive counterions.

When this system dries out, the hydrophobic interactions between the hydrocarbon regions of the polymer cations increase considerably, which causes the layer containing the polymer cations to shrink. Because the electrostatic attraction between the polycations and the microgel is very strong and the microgel layer is very firmly attached to the coated sheet of plastic, the ends of the strip bend upwards and the system curls up. When the air humidity is increased, it stretches back out.

The researchers hung one of their strips up in a chamber with controlled humidity conditions. By changing the humidity, they were able to make their artificial arm “grip” the handle of a small package and to “hold on” as it rose up. In another experiment, they hung a chain of paperclips to the end of one extended mini-arm. Cyclic changes in the humidity caused the arm to raise and lower this weight, which was 14 times as heavy as the arm itself, like a miniature weight-lifting exercise.

“Given that a human arm is approximately 6.5 % of the total mass of the human body, this is equivalent to a 75 kg human with a single arm that is capable of lifting 68.3 kg,” Serpe says to illustrate the strength of his miniature arm. Even hanging 52.2 g of weight from a curled-up arm was not enough to stretch it out. If a 75 kg human wanted to achieve a similar feat, he would have to keep his arm bent even with 1280 kg pulling on it.

About the Author
Dr. Michael J. Serpe is an assistant professor in the Department of Chemistry at the University of Alberta. His research is focused on using polymer-based materials for a variety of applications; with a particular focus on developing novel point-of-care diagnostics, water remediation systems, and polymer-based muscles and actuators. He was recently awarded the Petro-Canada Young Innovator Award for his research accomplishments.

Author: Michael J. Serpe, University of Alberta, Edmonton (Canada), http://www.chemistry.ualberta.ca/FacultyandStaff/Faculty/MichaelSerpe.aspx

Title: Polymer-Based Muscle Expansion and Contraction
Angewandte Chemie International Edition, Permalink to the article: http://dx.doi.org/10.1002/anie.201303475
Copy free of charge. We would appreciate a transcript of your article or a reference to it.

The original article is available from our online pressroom at http://pressroom.angewandte.org.

Michael J. Serpe | Angewandte Chemie
Further information:
http://pressroom.angewandte.org

More articles from Life Sciences:

nachricht New Model of T Cell Activation
27.05.2016 | Albert-Ludwigs-Universität Freiburg im Breisgau

nachricht Fungi – a promising source of chemical diversity
27.05.2016 | Leibniz-Institut für Naturstoff-Forschung und Infektionsbiologie - Hans-Knöll-Institut (HKI)

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Worldwide Success of Tyrolean Wastewater Treatment Technology

A biological and energy-efficient process, developed and patented by the University of Innsbruck, converts nitrogen compounds in wastewater treatment facilities into harmless atmospheric nitrogen gas. This innovative technology is now being refined and marketed jointly with the United States’ DC Water and Sewer Authority (DC Water). The largest DEMON®-system in a wastewater treatment plant is currently being built in Washington, DC.

The DEMON®-system was developed and patented by the University of Innsbruck 11 years ago. Today this successful technology has been implemented in about 70...

Im Focus: Computational high-throughput screening finds hard magnets containing less rare earth elements

Permanent magnets are very important for technologies of the future like electromobility and renewable energy, and rare earth elements (REE) are necessary for their manufacture. The Fraunhofer Institute for Mechanics of Materials IWM in Freiburg, Germany, has now succeeded in identifying promising approaches and materials for new permanent magnets through use of an in-house simulation process based on high-throughput screening (HTS). The team was able to improve magnetic properties this way and at the same time replaced REE with elements that are less expensive and readily available. The results were published in the online technical journal “Scientific Reports”.

The starting point for IWM researchers Wolfgang Körner, Georg Krugel, and Christian Elsässer was a neodymium-iron-nitrogen compound based on a type of...

Im Focus: Atomic precision: technologies for the next-but-one generation of microchips

In the Beyond EUV project, the Fraunhofer Institutes for Laser Technology ILT in Aachen and for Applied Optics and Precision Engineering IOF in Jena are developing key technologies for the manufacture of a new generation of microchips using EUV radiation at a wavelength of 6.7 nm. The resulting structures are barely thicker than single atoms, and they make it possible to produce extremely integrated circuits for such items as wearables or mind-controlled prosthetic limbs.

In 1965 Gordon Moore formulated the law that came to be named after him, which states that the complexity of integrated circuits doubles every one to two...

Im Focus: Researchers demonstrate size quantization of Dirac fermions in graphene

Characterization of high-quality material reveals important details relevant to next generation nanoelectronic devices

Quantum mechanics is the field of physics governing the behavior of things on atomic scales, where things work very differently from our everyday world.

Im Focus: Graphene: A quantum of current

When current comes in discrete packages: Viennese scientists unravel the quantum properties of the carbon material graphene

In 2010 the Nobel Prize in physics was awarded for the discovery of the exceptional material graphene, which consists of a single layer of carbon atoms...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Networking 4.0: International Laser Technology Congress AKL’16 Shows New Ways of Cooperations

24.05.2016 | Event News

Challenges of rural labor markets

20.05.2016 | Event News

International expert meeting “Health Business Connect” in France

19.05.2016 | Event News

 
Latest News

3-D model reveals how invisible waves move materials within aquatic ecosystems

30.05.2016 | Materials Sciences

Spin glass physics with trapped ions

30.05.2016 | Materials Sciences

Optatec 2016: Robust glass optical elements for LED lighting

30.05.2016 | Trade Fair News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>