Robotic Fish May Hold Key to Better Artificial Limbs
From: Medical Product Manufacturing News - June, 2001 - page 6
http://www.devicelink.com/mpmn/
By: Zachary Turke

Scientists at Massachusetts Institute of Technology (Cambridge, MA;
http://web.mit.edu) have developed a robotic fish incorporating whole
frog-muscle explants that may be the first step toward building better
prosthetic devices for humans. Based on Luigi Galvani`s 1786 discovery that
an electrical current makes a dissected frog`s legs twitch, this new research
explores the issue of tissue to replace the inefficient synthetic means of
momentum currently used in artificial limbs. The first successful example of
this technology is a 120-mm biomechatronic "fish" that combines an
electronics package with a 50-mm section of frog muscle. Buoyed by a
Styrofoam block in a glucose solution that serves as a source of energy, the
unit uses a microprocessor to send variable electrical signals to the muscle
tissue. The resulting contractions enable the fish to start, stop, and turn
with a maximum speed of 60 mm/sec. 

Using real muscle in prosthetic devices will yield many benefits, according
to researchers. Muscle has the ability to adapt to its environment, healing
and changing structure as required. It is also very efficient, generating as
much as 4000 kJ from 1 kg of glucose under aerobic conditions. This energy is
generated silently, eliminating many of the noise concerns associated with
traditional devices. Because it delivers great isometric force, hybrid
technology would also allow prosthetics to have extremities that are light
but still very strong. 

MIT scientists are presently working on developing muscle cultures that can
survive outside their source body for several months. The tissues currently
used remain effective for only a few hours. Other goals include creating the
technology necessary to engineer muscle tissues directly from small tissue
samples taken from the device user. Native sampling would allow the
prosthesis to be fully compatible with its beneficiary. Among the many
parties that have shown interest in this hybrid technology are the Pentagon`s
Defense Advanced Research Projects Agency, which may focus on developing
hybrid suits to increase the physical capabilities of U.S. soldiers. 
