Gel gains life-like motion
Technology Research News
Researchers from the University of Cambridge
in England and Lehigh University have shown that it is possible to make
a strip of hydrogel mimic the movements of a snail, inchworm and snake.
The ability could lead to new motion techniques for tiny machines,
including robots, and for manufacturing processes that involve moving
substances across surfaces.
The research also shows that there is an underlying unity in the
various forms of movement produced by legless animals.
The researchers' first theorized that the creep of a snail, crawl
of an inchworm, and back-and-forth motion of the snake could all be described
by one coherent theory. They then found a way to prove it. "After the
conceptual breakthrough, the main challenge was thinking of the simplest
experimental setup to realize it," said Lakshminarayanan Mahadevan, who
is now a professor of applied mathematics and mechanics at Harvard University.
The researchers tested the theory by cutting scales into the bottoms
of 2-centimeter-long strips of acrylamide hydrogel and placing them on
a vibrating table. They were able to cause the strips to mimic the three
types of legless locomotion by varying the angle of the scales and the
direction of vibration. The experiment shows that "a simple idea can explain
the various regimes of locomotion," said Mahadevan.
Most work on microelectromechanical devices that has to do with
moving objects around has focused on microfluidics -- controlling small
quantities of fluid, said Mahadevan. The hydrogel work shows that soft
solids can be moved around relatively easily using a fairly simple process,
The remaining challenge is to find a way to provide the vibrations
internally, said Mahadevan. "This can probably be done with a simple onboard
engine such as a mechanical-active gel that responds to external actuation
[from] electromagnetic or chemical fields" or temperature, he said.
Putting the power on-board would allow for a feedback loop that
allows the engine to respond to the way the gel deforms, or bends, according
to Mahadevan. Feedback like this allows organisms to respond to external
stimuli by changing gaits.
The researchers are working toward a more quantitative understanding
of the mechanisms involved in the gel movement in order to figure out
how to optimize the motions, said Mahadevan.
The next step is to understand optimal gaits and the transitions
between them, and to explore additional gaits like side-winding, slide-pushing
and concertina motion, according to Mahadevan. Sidewinder snakes twist
and turn to move. "Concertina motion is when the snake literally squeezes
itself into the shape of a concertina while pushing against the side of
a tube and then alternately drags itself or pushes forward," he said.
The gel devices could be used in practical applications in the
next couple of years, said Mahadevan. They could be used in microelectromechanical
systems, and robots that inspect crevices and other hard-to-get-to places,
Mahadevan's research colleagues were Manoj Chaudhury and Susan
Daniel. The work appeared in the December 15, 2003 issue of Proceedings
of the National Academy Of Sciences. The research was funded by the
Office of Naval Research (ONR).
Timeline: 2 years
TRN Categories: Materials Science and Engineering; MicroElectroMechanical
Story Type: News
Related Elements: Technical paper, "Biomimetic Ratcheting
Motion of a Soft, Slender, Sessile Gel," Proceedings of the National Academy
Of Sciences, December 15, 2003
December 31, 2003/January 7, 2004
Bots, humans play together
Light frozen in place
Gel gains life-like motion
Tool eases Grid monitoring
millions of vessels
images secure screens
Colors expand neural
Micro fuel cell runs
boosts solar cells
Shape key to strong
Research News Roundup
Research Watch blog
View from the High Ground Q&A
How It Works
News | Blog
Buy an ad link