Touchscreens that contain carbon nanotubes can be made of low-priced renewable raw materials. (Fraunhofer IPA).
Touchscreens are in—although the technology still has its price. The little
screens contain rare and expensive elements. This is the reason why researchers
at Fraunhofer are coming up with an alternative display made of low-priced
renewable raw materials available all over the world. The researchers are
presenting touchscreens that contain carbon nanotubes at the nano tech 2011
fair in Tokyo.
Just touching it slightly with the tips of your fingers is enough. You can
effortlessly write, navigate, open menu windows, or rotate images on
touchscreens. Within fractions of a second your touch is translated into
control commands that a computer understands. At first glance, this technology
borders on the miraculous, but in real life this mystery just is a wafer-thin
electrode under the glass surface of the display made of indium-tin-oxide, ITO.
This material is nothing short of ideal for use in touchscreens because it is
excellent at conducting slight currents and lets the colors of the display pass
through unhindered. But, there is a little problem: there are very few deposits
of indium anywhere in the world. In the long term, the manufacturers of electronic
gadgets are afraid that they will be dependent upon the prices set by
suppliers. This is the reason why indium is one of what people call
Therefore, private industry is very interested in alternatives to ITO that
are similarly efficient. The researchers at Fraunhofer have succeeded at coming
up with a new material for electrodes that is on the same level as ITO and on
top of it is much cheaper. Its main components are carbon nanotubes and
low-cost polymers. This new electrode foil is composed of two layers. One is
the carrier, a thin foil made of inexpensive polyethylenterephthalate PET used
for making plastic bottles. Then a mixture of carbon-nanotubes and electrically
conducting polymers is added that is applied to the PET as a solution and forms
a thin film when it dries.
In comparison to ITO, these combinations of plastics have not been
particularly durable because humidity, pressure or UV light put a strain on the
polymers. The layers became brittle and broke down. Only carbon nanotubes have
made them stable. The carbon nanotubes harden on the PET to create a network
where the electrically conducting polymers can be firmly anchored. That means
that this layer is durable in the long run. Ivica Kolaric, project manager from
Fraunhofer Institute for Manufacturing Engineering and Automation IPA, concedes
that “the electrical resistance of our layer is somewhat greater than that
of the ITO, but it’s easily enough for an application in electrical
systems.” Its merits are unbeatable: carbon is not only low-cost and
available all over the world. It is also a renewable resource that you can get
from organic matter such as wood. Kolaric and his colleagues will be presenting
their carbon touchdisplay at the 2011 nano tech fair. Since 2003 Fraunhofer
researchers show their developments at the annual trade show.
There are a whole series of implementations for the new technology. This
foil is flexible and can be used in a variety of ways. Kolaric sums up by
saying “we could even make photovoltaic foils out of it to line corrugated
roofs or other uneven structures.” The researcher has already set up pilot
production where the foil can be enhanced for a wide range of applications.