SINGAPORE Dec 26 A new way of assembling
things, called metamaterials, may in the not too distant future
help to protect a building from earthquakes by bending seismic
waves around it. Similarly, tsunami waves could be bent around
towns, and soundwaves bent around a room to make it soundproof.
While the holy grail of metamaterials is still to make
objects and people invisible to the eye, they are set to have a
more tangible commercial impact playing more mundane roles -
from satellite antennas to wirelessly charging cellphones.
Metamaterials are simply materials that exhibit properties
not found in nature, such as the way they absorb or reflect
light. The key is in how they're made. By assembling the
material - from photonic crystals to wire and foam - at a scale
smaller than the length of the wave you're seeking to
manipulate, the wave can, in theory, be bent to will.
This makes metamaterials the tool of choice for scientists
racing to build all sorts of wave-cloaking devices, including
the so-called invisibility cloak - a cover to render whatever's
inside effectively invisible by bending light waves around it.
"The invisibility cloak was just one more thing we were
discovering - that we have all this flexibility in this material
and here's another thing we can do," David Smith of Duke
University, widely regarded as one of the founding fathers of
metamaterials, said in a telephone interview. "But we're equally
interested in seeing this transition in making a difference in
Indeed, Smith's own journey from laboratory to factory
illustrates that while metamaterials have for some become
synonymous with "Harry Potter" cloaks, their promise is more
likely to be felt in a range of industries and uses, from
smaller communication devices to quake-proof buildings.
At the heart of both metamaterials and invisibility are
waves. If electromagnetic waves - whether visible light,
microwave or infrared - can be bent around an object it would
not be visible on those wavelengths. It was long thought you
couldn't control light in this way with natural materials as
their optical properties depended on the chemistry of the atoms
from which they were made.
It was only when Smith and his colleagues experimented with
altering the geometry of material in the late 1990s that they
found they could change the way it interacted with light, or
other kinds of wave - creating metamaterials. With that, says
Andrea Alu, an associate professor at the University of Texas at
Austin, scientists found "it may be possible to challenge rules
and limitations that were for centuries considered written in
The past decade has seen an explosion in research that has
built on Smith's findings to make objects invisible to at least
some forms of light.
"There have now been several demonstrations of cloaking at
visible wavelengths, so cloaking is truly possible and has been
realised," says Jason Valentine of Vanderbilt University, who
made one of the first such cloaks. These, however, have
limitations - such as only working for certain wavelengths or
from certain angles. But the barriers are falling fast, says
In the past year, for example, Duke University's Yaroslav
Urzhumov has made a plastic cloak that deflects microwave beams
using a normal 3D printer, while Alu has built an ultra-thin
cloak powered by electric current.
Funding much of this U.S. research is the military.
Urzhumov said in an email interview that the U.S. Department
of Defense is "one of the major sponsors of metamaterials and
invisibility research in the U.S." The Defense Advanced Research
Projects Agency, which commissions advanced research for the
Department of Defense, has funded research into metamaterials
since 2000, according to the department's website.
Military interest in metamaterials was primarily in making a
cloak, said Miguel Navarro-Cia of Imperial College London, who
has researched the topic with funding from the European Defence
Agency and U.S. military.
But an invisibility cloak needn't be a sinister tool of war.
Vanderbilt's Valentine suggests architectural usage. "You
could use this technology to hide supporting columns from sight,
making a space feel completely open," he said.
Other potential uses include rendering parts of an aircraft
invisible for pilots to see below the cockpit, or to rid drivers
of the blind spot in a car.
Military or not, this is all some way off.
"Most invisibility cloaks, essentially, are still in the
research stage," says Ong Chong Kim, director at the National
University of Singapore's Centre for Superconducting and
Ong and others say that while metamaterials may not yet be
making objects invisible to the eye, they could be used to
redirect other kinds of waves, including mechanical waves such
as sound and ocean waves. French researchers earlier this year,
for example, diverted seismic waves around specially placed
holes in the ground, reflecting the waves backward.
Ong points to the possibility of using what has been learned
in reconfiguring the geometry of materials to divert tsunamis
from strategic buildings.
Elena Semouchkina, a pioneer on cloaking devices at Michigan
Technological University, points to screening antennas so they
don't interfere with each other, protecting people from harmful
radiation or acoustic pressure, and even preventing buildings
from destruction from seismic waves.
Metamaterials could also absorb and emit light with
extremely high efficiency - for example in a high-resolution
ultrasound - or redirect light over a very small distance. This,
says Anthony Vicari of Lux Research, "could be used to improve
fibre optical communications networks, or even for optical
communications within microchips for faster computing."
Indeed, there's clearly a growing appetite for
commercialising the unique properties of metamaterials.
One of the first to do so was the new defunct Rayspan Corp,
a California-based company whose antennas found their way into
WiFi routers from networking manufacturer Netgear Inc
and a superflat smartphone from LG Electronics Inc.
The antennas were smaller, flatter and performed better than
other options, but integrating them into the rest of the phone
proved difficult, said former Rayspan executives. A spokesman
for LG said the project was no longer active and LG had no plans
to apply metamaterials in other products.
"One thing from my experience as an entrepreneur is that
technology gets very excited about what it's doing in the lab,"
said Maha Achour, who co-founded Rayspan, "but the reality when
you commercialise things is completely different." The company's
patents have since been sold to an undisclosed buyer.
The lessons have been learned. Now, the focus has shifted to
using metamaterials in products in markets where they can more
easily gain a commercial foothold.
Smith, who built the first metamaterials in 1999, has led
the charge, teaming up with Intellectual Ventures, a patent
portfolio firm, to spin off two companies: Kymeta Corp, making
flat-panel antennas for satellite communications, and Evolv
Technologies, which hopes to make a lighter, faster and portable
airport scanner - with no moving parts. Kymeta, in partnership
with satellite operators Inmarsat and O3b Networks,
hopes to ship in early 2015.
The two fields were chosen from a shortlist of 20 potential
markets, Smith said. "They're the same metamaterials behind the
cloak, but we were looking for more near-term applications."
The next likely consumer use of metamaterials could be in
the wireless charging of devices, an area attracting keen
Mark Gostock of ISIS Innovation Ltd, an Oxford University
research commercialisation firm, said he was in talks with
several manufacturers to licence ISIS' technology. Samsung
Electronics has filed several patents related to
metamaterials and wireless charging, but declined to comment for
Other companies that cite metamaterials in their patent
filings include Harris Corp, NEC Corp,
Hewlett-Packard Co and Panasonic Corp.
Eventually, says Wil McCarthy, chief technology officer of
Denver-based smart window maker RavenBrick LLC and holder of a
patent he hopes will bring metamaterials to polarising windows,
metamaterials will be incorporated without much fanfare.
"The people buying these products will have no idea how they
work, and won't know or care that they're doing things that were
previously considered impossible," he says.