Touchscreens are the latest ‘must have’ technology. The little screens contain rare and expensive elements, and the quantities are dwindling and are skyrocketing in price. 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 this year’s nano tech fair in Tokyo. Just touching it slightly with the tips of your fingers is enough. Just like other current touchscreens, you can effortlessly write, navigate, open menu windows or rotate images on touchscreens. The main touch sensor is a wafer-thin electrode under the glass surface of the display made of indium-tin-oxide.
There-in lies the problem as there are very few deposits of indium anywhere in the world. 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.
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