Conductive, Shape-Shifting Metal Rubber
WINTER 2004 - ARTICLE #4801
Conductive, Shape-Shifting Material Increases Electronics' Durability
By T. Robinson
Dr. Richard Claus of NanoSonic, Inc.
Conventional flexible circuits used in cell phones and laptops fail
whenoverused, strained, or stretched. But, a new conductive material capable
of elongating and returning to its original form without failure is now
available for testing.
Photo: Stretched. NanoSonic President Rick Claus and researchers Jennifer
Lalli and Jeff Mecham display the capabilities of Metal RubberTM , a highly
conductive material that stretches like rubber, but conducts electricity the
way metal does.
The new material, called Metal Rubber(TM) and developed by NanoSonic, Inc.
(Blacksburg, VA), can be applied to any existing or new electronic device
that requires wires to bend and stretch. The robust, low-weight, and
radiation- resistant material evolved out of nanotechnology research.
Using its MDA-funded low-temperature electrostatic self-assembly (ESA)
manufacturing process (see "NanoSonic Demonstrates Self-Assembly Process"
MDA Update Summer 2001), NanoSonic developed nanocomposites, which it
layered together to form Metal Rubber. ESA enables NanoSonic to customize
Metal Rubber's characteristics (e.g., conductivity and modulus). The
material does not fall apart when deformed and is highly conductive even
though it just contains parts per million of metal.
The commercial applications using this conductive, shape-shifting material
are limitless. A search on the Internet yields visionary ideas like morphing
aircraft wings, flexible, roll-up keyboards, or Metal Rubber jackets that
get longer or shorter according to the temperature. But, for now, NanoSonic
is focused on more near-term applications such as flexible circuits and
Laptops and cell phones that flip open contain flexible circuits connecting
the base to the screen. These circuits fail when they are bent too often.
NanoSonic's Metal Rubber is much more flexible and elastic than typical flex
circuits. It can stretch up to 300 percent its size and return to its
original shape while remaining conductive.
Metal Rubber may also be used as flexible interconnects or strain sensors in
the missile defense system. For example, it may be used in the development
of flexible, conductive, and radiation-resistant components such as
interconnects for flexible communication and tracking platforms like the
High Altitude Airship or space-based radar. Such flexible aerospace
structures may also require flexible strain sensors to determine shape and
displacement, and these potentially may be implemented using Metal Rubber
materials. The Lockheed Martin Corporation recently signed an alliance
agreement with NanoSonic for possible uses of NanoSonic's novel materials
NanoSonic is investigating the use of Metal Rubber as a stress/strain sensor
as well. With the material's good stress/strain linearity and broad range
(several 100 percent strain), it could be used as jackets or coatings for
cables used in wiring harnesses. Instead of having to assess each conductor
of the actual cable, a maintenance technician would inspect only the Metal
Rubber jacket to determine if the cable has been somehow over-strained.
NASA's Jet Propulsion Laboratory may also apply Metal Rubber to its research
and development of motion-producing devices called artificial muscles. When
stimulated electrically, artificial muscle materials react by flexing and
changing shape and could replace bulky motors, electromagnets, and other
actuators. But wires, which are not as flexible as artificial muscles, need
to be attached to provide the electric charge.
NanoSonic president Rick Claus has been the keynote speaker at many
artificial muscle conferences recently to describe the benefits of using
Metal Rubber instead of wires on artificial muscles. To accommodate their
inflexibility, multiple wires are used to weigh down the artificial muscles
and mechanically constrict them. Instead of doing this, NanoSonic's Metal
Rubber may be a low-weight, robust replacement that can match the movements
of the artificial muscles and conduct the electrical charge.