i3 - July/August 2017 - 12

By Murray Slovick

A T EC H TO WATC H

Graphene:
Consumer Technology
Apps to Come

 G  

raphene is a thin layer of carbon atoms tightly bonded
together in a hexagonal, honeycomb lattice. It is light,
transparent, extremely hard and has more tensile
strength than steel. With outstanding electrical, physical and
chemical properties as well as an atomic-level thinness -
only 0.3 nanometers thick, about one hundred thousandth
of a human hair - graphene has great flexibility. Researchers
consider graphene an ideal candidate for future consumer
technology products. Here are three cases.

1. A Single Chip

Traditional speakers mechanically vibrate to
produce sound, with a moving coil or membrane pushing the air back and forth. But
researchers from the University of Exeter in the
UK are using graphene to generate complex
and controllable sound without moving parts
by using thermoacoustics - producing sound
via the rapid heating and cooling of material.
To simplify, it works by rapidly heating
and cooling a layer of the atomically thin
material using an alternating electric current.
This thermal variation is transferred to the
air, which expands and contracts, thus
generating sound waves. Dr. David Horsell,
a senior lecturer in the Quantum Systems and
Nanomaterials Group at Exeter and his team
found that by controlling the electrical current
through graphene, they could produce sound
and also change its volume to specify how
each frequency component is amplified.
They have combined a speaker, amplifier and
graphic equalizer into one chip. This could
12

JULY/AUGUST 2017

conditions of superconducting circuits,
and based on two-dimensional materials.
The capacitor consists of insulating boron
nitride sandwiched between two graphene
sheets. Thanks to this structure
and graphene's unusual properResearchers
ties, the incoming charge is not
consider graphene an proportional to the voltage that
ideal candidate for
future consumer tech- is generated. This nonlinearity
is a necessary step in the pronology products.
cess of generating quantum
bits. The resulting device could significantly
improve the way quantum information is processed. This research was published in
2D Materials and Applications.
Graphene-based capacitors also have
potential applications such as creating nonlinear high-frequency circuits - up to the
terahertz regime. Most portable, wireless
systems use reconfigurable circuits that can
adjust an antenna to transmit and receive data
in various frequency bands. Technologies,
such as MEMS or CMOS, use silicon or metal
and do not work well at high frequencies.

make mobile phone screens that transmit
both pictures and sound possible.
Other applications include ultrasound
imaging for use in hospitals. The University
of Exeter published "Multi-frequency sound
production and mixing in graphene" by
Dr. Horsell and Mark Heath in the journal
Scientific Reports.

2.

Quantum Computing
Computers operate using binary code
composed of bits with a value of either
0 or 1. In quantum computers, the bits are
replaced by qubits (quantum bits), which
can be in two states simultaneously. One of
the keys to developing a quantum computer
is to create quantum bits that are stable
and can function at very low temperatures.
Researchers at the Laboratory of Photonics
and Quantum Measurements at Ecole
Polytechnique Federale de Lausanne (EPFL)
are investigating a graphene-based quantum capacitor compatible with cryogenic

3. OLEDs

The Fraunhofer Institute for Organic
Electronics, Electron Beam and Plasma
Technology (FEP, Dresden Germany)
together with research partners, has
successfully produced OLED electrodes
from graphene in a vacuum with an area
of 2 × 1 square centimeters. In a steel chamber, a wafer plate of high-purity copper
is heated to about 800 degrees Celsius.
The team then supplied a mixture of methane and hydrogen and initiated a chemical
reaction. The methane dissolves in the copper and forms carbon atoms, which spread
on the surface. After a cooling phase, a protective polymer is placed on the graphene
and the copper plate is etched away to
reveal a single atom layer of pure graphene.
Dr. Beatrice Beyer, project leader, says
products could launch in two years. Due to
their flexibility, the graphene electrodes are
ideal for touchscreens and won't break if
dropped. Instead of glass, a transparent polymer film is used. The Fraunhofer Institute
partnered with Spanish company Graphenea
S.A., to produce the graphene electrodes,
and with British company Aixtron Ltd.,
to build the CVD reactors.
Researchers are working to eliminate
or minimize impurities and defects that
occur during the transfer of the wafer-thin
graphene to another carrier material.
Stay tuned for advances.
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