MATTER & ENERGY
New fabric could
make cool clothes
Plastic covered in tiny pores
lets heat out yet blocks light
B Y MEGHAN ROSEN
Plastic cling wrap with nano-sized pores
could give “cool clothes” a new meaning.
The material lets heat escape, instead
of trapping it like traditional fabrics,
Stanford University materials scientist Yi Cui and colleagues report in the
Sept. 2 Science. It could help people
keep cool in hot weather, Cui says, and
even save energy by reducing the use of
“It’s a very bold new idea,” says MIT
physicist Svetlana Boriskina, who
wrote an accompanying commentary.
Demand for the new material could be
far-reaching, she says. “Every person
who wears clothes could be a potential
user of this product.”
Current cooling devices include wear-
able fans, which rely on evaporation to
cool human skin. But skin also sheds
heat in another way — as infrared radia-
tion. Clothing holds this heat close to
the body, Cui says. If infrared radiation
could instead pass through fabric, he
reasoned, people would feel a lot cooler.
But the fabric would have to be transparent only to infrared wavelengths. To
visible light, it would need to be opaque.
Otherwise, the clothing would be
Cui found just one material that satisfied both requirements: a commercially
available plastic used in lithium-ion
batteries. The material, nanoporous
polyethylene, or nanoPE, is a cling wrap–
like plastic that lets infrared radiation
through. But unlike cling wrap, the material isn’t clear: It blocks visible light.
Tiny pores speckled throughout the
fabric act as obstacles to visible light,
Boriskina says. When blue light, for
example, hits the pores, it scatters. So do
other colors. The light “bounces around
in different directions and scrambles
together,” she says. To human eyes, the
Traditional textiles like polyester (top) and
cotton (middle) trap body heat, but a plastic
material called nanoPE (bottom) lets heat escape. Researchers are looking at ways of using
the material to make high-tech fabric.
weather bomb–related S waves using a
network of 202 seismic stations in Japan.
Typically, the waves are lost within
Earth’s natural seismic background
noise. By combining and analyzing the
data collected by the extra-sensitive
seismometers, however, the researchers
teased out the S wave signals.
The waves originated from a North
Atlantic cyclone. That storm produced
two types of S waves: SV waves (which
shift material vertically relative to Earth’s
surface and can form from P waves) and
SH waves (which shift material horizontally and have less clear origins).
Combining measurements of P, SV
and SH waves will “ultimately provide
better maps of Earth’s mantle and maybe
even the core,” says Keith Koper, a seis-
mologist at the University of Utah in
Salt Lake City. s
resulting color is white.
The pores scatter visible light because
they’re both in the same size range: The
diameters of the pores span 50 to 1,000
nanometers, and the wavelengths of
visible light range from 400 to 700 nano-
meters. Infrared radiation emitted by
the body as heat has a much larger wave-
length, 7,000 to 14,000 nanometers, so
the plastic’s tiny pores can’t block it.
The pores are kind of like small rocks
at a beach, Boriskina says. They’ll interfere with the motion of small waves, but
big waves will wash right over.
Cui and colleagues tested nanoPE by
laying it on a hot plate warmed up to
human skin temperature, 33.5° Celsius.
NanoPE raised the “skin” temperature
by just 0.8 degrees (to 34.3° C). “But
when you put on cotton, my God, it rose
to 37,” Cui says. “It’s hot!”
The researchers also tried to make
nanoPE more wearable than plas-
tic wrap. They coated it with a water-
wicking chemical, punched holes in it to
make it breathable and layered it with
cotton mesh. Now, the team is work-
ing on weaving the fabric to make it feel
more like traditional textiles.
“Within five years, I hope someone
will start wearing it,” Cui says. “And
within 10 years, I hope most people will
be wearing it.” s
chance, the researchers say. There hasn’t
been enough time for a helpful mutation
to arise and spread across the island. So
the variants were probably already pres-
ent in a small number of animals and
natural selection (via the tumor) weeded
out the individuals that didn’t carry them.
Those two genome regions contain
seven genes, some of which have been
shown to be involved in fighting cancer or
controlling the immune system in other
mammals. The team isn’t sure which
genes boost survival or how they work.
The variants don’t necessarily make dev-
ils completely immune to the tumor; the
variants may just allow infected individ-
uals to live long enough to pass on their
genes, Storfer says. Other genes may also
contribute to survival, he says.
Genetics may help researchers bet-
ter predict how the disease will spread
in remaining uninfected populations.
Breeding programs could incorporate
animals that carry the survival variants
to build resistance.
Comparative genomicist Katherine
Belov of the University of Sydney says the
resistance genes shouldn’t be bred into
all devils. They need genetic diversity to
cope with other diseases and unknown
challenges down the line, she says. s