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 Biology in a twist -- deciphering the origins of cell behavior
31.03.2015 | National University of Singapore

nachricht Speech dynamics are coded in the left motor cortex
31.03.2015 | Universitätsmedizin Göttingen - Georg-August-Universität

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Experiment Provides the Best Look Yet at 'Warm Dense Matter' at Cores of Giant Planets

In an experiment at the Department of Energy's SLAC National Accelerator Laboratory, scientists precisely measured the temperature and structure of aluminum as...

Im Focus: Energy-autonomous and wireless monitoring protects marine gearboxes

The IPH presents a solution at HANNOVER MESSE 2015 to make ship traffic more reliable while decreasing the maintenance costs at the same time. In cooperation with project partners, the research institute from Hannover, Germany, has developed a sensor system which continuously monitors the condition of the marine gearbox, thus preventing breakdowns. Special feature: the monitoring system works wirelessly and energy-autonomously. The required electrical power is generated where it is needed – directly at the sensor.

As well as cars need to be certified regularly (in Germany by the TÜV – Technical Inspection Association), ships need to be inspected – if the powertrain stops...

Im Focus: 3-D satellite, GPS earthquake maps isolate impacts in real time

Method produced by UI researcher could improve reaction time to deadly, expensive quakes

When an earthquake hits, the faster first responders can get to an impacted area, the more likely infrastructure--and lives--can be saved.

Im Focus: Atlantic Ocean overturning found to slow down already today

The Atlantic overturning is one of Earth’s most important heat transport systems, pumping warm water northwards and cold water southwards. Also known as the Gulf Stream system, it is responsible for the mild climate in northwestern Europe. 

Scientists now found evidence for a slowdown of the overturning – multiple lines of observation suggest that in recent decades, the current system has been...

Im Focus: Robot inspects concrete garage floors and bridge roadways for damage

Because they are regularly subjected to heavy vehicle traffic, emissions, moisture and salt, above- and underground parking garages, as well as bridges, frequently experience large areas of corrosion. Most inspection systems to date have only been capable of inspecting smaller surface areas.

From April 13 to April 17 at the Hannover Messe (hall 2, exhibit booth C16), engineers from the Fraunhofer Institute for Nondestructive Testing IZFP will be...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

World Conference On Regenerative Medicine 2015: Registration And Abstract Submission Now Open

25.03.2015 | Event News

University presidents from all over the world meet in Hamburg

19.03.2015 | Event News

10. CeBiTec Symposium zum Big Data-Problem

17.03.2015 | Event News

 
Latest News

Biology in a twist -- deciphering the origins of cell behavior

31.03.2015 | Life Sciences

Wrapping carbon nanotubes in polymers enhances their performance

31.03.2015 | Materials Sciences

Research Links Two Millennia of Cyclones, Floods, El Niño

31.03.2015 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>