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Genius Materials on the ISS -
presented by Science@NASA
If you have a smartphone,
take it out and run your fingers along the glass surface.
It's cool to the touch,
incredibly thin and strong,
and almost impervious to scratching.
You're now in contact with a 'smart material.'
Smart materials don't occur naturally.
Instead, they are designed by engineers
working at the molecular level to produce substances
made-to-order for futuristic applications.
The Corning Gorilla Glass
that overlays the displays of many smartphones
is a great example.
It gets it toughness, in part,
from 'fat' potassium ions
stuffed into the empty spaces between old-fashioned glass molecules.
When the molten glass cools during manufacturing,
dense-packed molecules solidify into a transparent armor
that gives Gorilla Glass its extraordinary properties.
Around the world,
designers are working on other smart materials
such as alloys that can change shape on demand,
plastics that heal themselves when ruptured,
and fluids that obey magnetic commands to flow or stiffen
under computer control.
'One of the great challenges in creating a smart material
is arranging the molecules,'
says Eric Furst of the University of Delaware.
'They're so small!'
Furst wants to create a new class of materials, beyond smart.
'We need 'genius materials'--
materials that arrange themselves' he says.
The research to accomplish this is already underway
on the International Space Station.
Furst is the principal investigator
of an experiment called InSPACE-3.
In the microgravity of Earth orbit,
vials of fluid mixed with very small 'colloidal' particles
(about a millionth of a meter in diameter)
are exposed to magnetic fields.
Magnetism can be switched on and off again very rapidly.
This jostles the particles,
causing them to bump together
and self-assemble into microscopic structures
These structures can be very difficult to predict
even using cutting edge models running on supercomputers.
'Astronauts enjoy watching this process in action through microscopes,'
says Furst.
'Because the samples are backlit by a green lamp,
they sometimes call it the 'green blob experiment.''
Furst recently won an award
from the American Astronautical Society
for his work on InSPACE-3.
'I'm excited,' he continues.
'Just by toggling a magnetic field,
we're learning how to take many kinds of microscopic building blocks
and get them to spontaneously form interesting structures.'
Recently, observers have seen the colloidal particles
forming long fibrous chains.
Furst speculates that these could lead to materials that conduct heat
or electricity in one direction only.
The experiment has also yielded crystalline structures
that the team is just beginning to investigate.
The fluids underlying these tests are themselves very smart.
They are called magnetorheological
or 'MR' fluids
because they harden or change shape
when they feel a magnetic field.
If you own a sports car or a Cadillac,
you might have MR fluids in your shock absorbers.
The stiffness of magnetic shocks
can be electronically adjusted thousands of times per second,
providing a remarkably smooth ride.
Similar but more powerful devices
have been installed at Japan's National Museum of Emerging Science
and China's Dong Ting Lake Bridge.
They're there to counteract vibrations
caused by earthquakes and gusts of wind.
Some researchers have speculated
that MR fluids might one day flow through the actuators
and hydraulic dampers of robots,
moving artificial joints and limbs
in lifelike fashion.
Furst and colleagues are using these fluids
as a laboratory for studying self-assembly.
MR fluids are, by definition,
responsive to the magnetic nudging that sets self-assembly in motion.
Furthermore, in space
the particles don't sediment out due to gravity.
'We can study the full 3D evolution of the material,' he adds.
Varying the shape of the colloidal particles,
the cadence of magnetic toggling,
the temperature of the fluid
and other factors will allow researchers and astronauts
to further explore the frontiers of self-assembly.
Touch the surface of your smartphone again.
That's just the beginning.
For more updates about genius research on the ISS,
visit science.nasa.gov.