Saving the Touch-Screen: the search for new Nanotech Crystals
Until the late 1980s, touch-screen technology was considered unreliable and imprecise, but in the era of smartphones and tablets, fast, accurate capacitive touchscreens are everywhere.
Such screens are based on transparent crystals that conduct electricity and mostly the compound used is indium tin oxide (ITO).
As a powder, indium tin oxide looks a pale yellow-green but when deposited as a thin film it becomes transparent and conducts electricity.
However, indium is running out and increasingly expensive. Internationally the race is on to find an alternative.
Whatever that turns out to be, it must be low cost, boast high conductivity and deliver good optical transparency.
Fujitsu pioneered the flexible polymer PEDOT. While this did not have anywhere near the conductivity of ITO and had questionable stability, it is improving with new formulations.
Silver nanowires could offer a way forward, as could graphene and a large number of other compounds, however, easily etchable zinc oxide is a likely candidate - if it can be made more stable. It would also be cheaper and more environmentally friendly.
The University of Wisconsin-Madison has a cross-disciplinary team developing chemically-coated zinc oxide touch-screen alternatives. This involves coating zinc oxide crystals in different chemicals to change how it behaves and then to find out if it could be a viable option for use as semiconductors in technology.