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With potential applications including wearable biomedical sensors, or ‘heads-up displays’ that let pilots monitor the environment while reading flight data, transparent electronics could offer a unique advantage to users in a variety of sectors.
Silver nanowire networks are promising candidates, as they are cheap, flexible and straightforward to fabricate. Current manufacturing methods create random nanowire alignment that is insufficient for advanced applications, however.
The team from Osaka University used high resolution printing to fabricate centimetre scale cross-aligned silver nanowire arrays, with reproducible feature sizes from 20 to 250 microns.
As a proof-of-concept, the team used their arrays to detect electrophysiological signals from plants. The researchers first created a patterned polymer surface to define the subsequent nanowire feature size. Using a glass rod to sweep silver nanowires across the pattern led to either parallel or cross-aligned nanowire networks, depending on the direction of the sweep. Nanowire cross-alignment, alignment within the pattern, and electro-optical properties were “impressive”, a research announcement said.
The researchers demonstrated the technology by monitoring the electric potential of Brazilian waterweed leaves. Because the nanowire arrays are transparent, the researchers were able to keep the leaf under visual observation while acquiring data over long periods of time. A sheet of between 2 and 3 microns conformed to the surface of a leaf without causing damage.
Transparent electronics must be simple and inexpensive to mass produce for widespread application. Promising areas include biomedicine, civil engineering and agriculture.
The Osaka University researchers plan to make further technical improvements, such as incorporating graphene onto the nanowire's surface. This will improve the uniformity of the microelectrode sheet resistance.
The research will be published in Advanced Intelligent Systems.
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