For those who find Google Glass
indiscreet, electronic contact lenses that outfit the user’s cornea with a
display may one day provide an alternative. Built by researchers at several
institutions, including two research arms of Samsung, the lenses use new nanomaterials
to solve some of the problems that have made contact-lens displays less than
practical. A group led by researchers at the Ulsan National Institute of
Science and Technology, mounted a light-emitting diode on an off-the-shelf soft
contact lens, using a material the researchers developed: a transparent, highly
conductive, and stretchy mix of graphene and silver nanowires. The researchers
tested these lenses in rabbits—whose eyes are similar in size to humans’—and
found no ill effects after five hours. The animals didn’t rub their eyes or
grow bloodshot, and the electronics kept working.
They found that sandwiching
silver nanowires between sheets of graphene yielded a composite with much lower
electrical resistance than either material alone. The industry standard for a
transparent conductor is a resistance of 50 ohms per square or less. Their
material has a resistance of about 33 ohms per square. The material also
transmits 94 percent of visible light, and it stretches. The researchers make
these conductive sheets by depositing liquid solutions of the nanomaterials on
a spinning surface, such as a contact lens, at low temperatures. Working with
researchers at Samsung, they coated a contact lens with the stretchy conductor,
and then placed a light-emitting diode on it. Although it would be an
exaggeration to call this a display, since there is just one pixel, its
possible this kind of material will be a necessary component in future
contact-lens displays.
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