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 Genetic Regulation of the Thymus Function Identified
23.08.2016 | Universität Basel

nachricht Sun protection for plants - Plant substances can protect plants against harmful UV radiation
22.08.2016 | Max-Planck-Institut für Molekulare Pflanzenphysiologie

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: X-ray optics on a chip

Waveguides are widely used for filtering, confining, guiding, coupling or splitting beams of visible light. However, creating waveguides that could do the same for X-rays has posed tremendous challenges in fabrication, so they are still only in an early stage of development.

In the latest issue of Acta Crystallographica Section A: Foundations and Advances , Sarah Hoffmann-Urlaub and Tim Salditt report the fabrication and testing of...

Im Focus: Piggyback battery for microchips: TU Graz researchers develop new battery concept

Electrochemists at TU Graz have managed to use monocrystalline semiconductor silicon as an active storage electrode in lithium batteries. This enables an integrated power supply to be made for microchips with a rechargeable battery.

Small electrical gadgets, such as mobile phones, tablets or notebooks, are indispensable accompaniments of everyday life. Integrated circuits in the interiors...

Im Focus: UCI physicists confirm possible discovery of fifth force of nature

Light particle could be key to understanding dark matter in universe

Recent findings indicating the possible discovery of a previously unknown subatomic particle may be evidence of a fifth fundamental force of nature, according...

Im Focus: Wi-fi from lasers

White light from lasers demonstrates data speeds of up to 2 GB/s

A nanocrystalline material that rapidly makes white light out of blue light has been developed by KAUST researchers.

Im Focus: Every atom counts

Malignant cancer cells not only proliferate faster than most body cells. They are also more dependent on the most important cellular garbage disposal unit, the proteasome, which degrades defective proteins. Therapies for some types of cancer exploit this dependence: Patients are treated with inhibitors, which block the proteasome. The ensuing pile-up of junk overwhelms the cancer cell, ultimately killing it. Scientists have now succeeded in determining the human proteasome’s 3D structure in unprecedented detail and have deciphered the mechanism by which inhibitors block the proteasome. Their results will pave the way to develop more effective proteasome inhibitors for cancer therapy.

In order to understand how cellular machines such as the proteasome work, it is essential to determine their three-dimensional structure in detail. With its...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

A week of excellence: 22 of the world’s best computer scientists and mathematicians in Heidelberg

12.08.2016 | Event News

Towards the connected, automated and electrified automobiles: AMAA conference in Brussels

02.08.2016 | Event News

Clash of Realities 2016: 7th Conference on the Art, Technology and Theory of Digital Games

29.07.2016 | Event News

 
Latest News

New microchip demonstrates efficiency and scalable design

23.08.2016 | Information Technology

Genetic Regulation of the Thymus Function Identified

23.08.2016 | Life Sciences

Biomass turnover time in ecosystems is halved by land use

23.08.2016 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>