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PUBLIC RELEASE DATE:
20-Mar-2012

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Contact: Michael Bishop
michael.bishop@iop.org
44-117-930-1032
Institute of Physics
@PhysicsNews

Jellyfish inspires latest ocean-powered robot

American researchers have created a robotic jellyfish, named Robojelly, which not only exhibits characteristics ideal to use in underwater search and rescue operations, but could, theoretically at least, never run out of energy thanks to it being fuelled by hydrogen.

Constructed from a set of smart materials, which have the ability to change shape or size as a result of a stimulus, and carbon nanotubes, Robojelly is able to mimic the natural movements of a jellyfish when placed in a water tank and is powered by chemical reactions taking place on its surface.

"To our knowledge, this is the first successful powering of an underwater robot using external hydrogen as a fuel source," said lead author of the study Yonas Tadesse.

The creators of Robojelly, from Virgina Tech, have presented their results today, 21 March, in IOP Publishing's journal Smart Materials and Structures.

The jellyfish is an ideal invertebrate to base the vehicle on due to its simple swimming action: it has two prominent mechanisms known as "rowing" and "jetting".

A jellyfish's movement is down to circular muscles located on the inside of the bell - the main part of the body shaped like the top of an umbrella. As the muscles contract, the bell closes in on itself and ejects water to propel the jellyfish forward. After contracting, the bell relaxes and regains its original shape.

This was replicated in the vehicle using commercially-available shape memory alloys (SMA) - smart materials that "remember" their original shape - wrapped in carbon nanotubes and coated with a platinum black powder.

The robot is powered by heat-producing chemical reactions between the oxygen and hydrogen in water and the platinum on its surface. The heat given off by these reactions is transferred to the artificial muscles of the robot, causing them to transform into different shapes.

This green, renewable element means Robojelly can regenerate fuel from its natural surroundings and therefore doesn't require an external power source or the constant replacement of batteries.

At the moment, the hydrogen-powered Robojelly has been functioning whilst being clamped down in a water tank. The researchers admit that the robot still needs development to achieve full functionality and efficiency; however, the potential can be seen in this video (http://www.youtube.com/watch?v=U2OSJQhHQp8) where the robot is powered by electricity.

"The current design allows the jellyfish to flex its eight bell segments, each operated by a fuel-powered SMA module. This should be sufficient for the jellyfish to lift itself up if all the bell segments are actuated.

"We are now researching new ways to deliver the fuel into each segment so that each one can be controlled individually. This should allow the robot to be controlled and moved in different directions," Tadesse continued.

This study is part of the MURI program sponsored by Office of Naval Research.

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From 21 March, this paper can be downloaded from http://iopscience.iop.org/0964-1726/21/4/045013

Notes to Editors

Contact

1. For further information, a full draft of the journal paper or contact with one of the researchers, contact IOP Press Officer Michael Bishop:
Tel: 0117 930 1032
E-mail: Michael.Bishop@iop.org

Hydrogen fuel-powered bell segments of biomimetic jellyfish

2. The published version of the paper "Hydrogen fuel-powered bell segments of biomimetic jellyfish" Tadesse Y et al 2012 Smart Mater. Struct. 21 045013 will be freely available online from 21 March. It will be available at http://iopscience.iop.org/0964-1726/21/4/045013.

Smart Materials and Structures

3. Smart Materials and Structures is a research journal dedicated to technical advances in smart materials, systems and structures, including materials, sensing and actuation, optics and electromagnetics, structures, control and information processing.

IOP Publishing

4. IOP Publishing provides publications through which leading-edge scientific research is distributed worldwide. IOP Publishing is central to the Institute of Physics (IOP), a not-for-profit society. Any financial surplus earned by IOP Publishing goes to support science through the activities of IOP. Beyond our traditional journals programme, we make high-value scientific information easily accessible through an ever-evolving portfolio of community websites, magazines, conference proceedings and a multitude of electronic services. Focused on making the most of new technologies, we're continually improving our electronic interfaces to make it easier for researchers to find exactly what they need, when they need it, in the format that suits them best. Go to http://ioppublishing.org/

The Institute of Physics

5. The Institute of Physics is a leading scientific society promoting physics and bringing physicists together for the benefit of all.

It has a worldwide membership of around 40 000 comprising physicists from all sectors, as well as those with an interest in physics. It works to advance physics research, application and education; and engages with policy makers and the public to develop awareness and understanding of physics. Its publishing company, IOP Publishing, is a world leader in professional scientific communications. Go to www.iop.org



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