A team of scientists from Nanjing University and Lanzhou University of Technology has developed a stretchable light-emitting device that operates at low voltages and is safe for human skin.
A stretchable light-emitting device becomes an epidermal stopwatch. Image credit: Zhou et al, doi: 10.1021/acsmaterialslett.9b00376.
Alternating current electroluminescent displays (ACELs) are an emerging form of light-emitting device.
They can be stuck on skin or other surfaces like a temporary tattoo.
However, they require relatively high voltages to achieve sufficient brightness, which could create safety concerns.
A research team led by Nanjing University’s Dr. Desheng Kong wanted to develop an ACEL that could operate at lower voltages and thus be safer for human skin.
To make their device, the researchers sandwiched an electroluminescent layer, made of light-emitting microparticles dispersed in a stretchable dielectric material, between two flexible silver nanowire electrodes.
The device contained a new type of dielectric material — in the form of ceramic nanoparticles embedded in a rubbery polymer — that increased the brightness compared with existing ACEL displays.
Dr. Desheng Kong and colleagues used this material to make a four-digit stopwatch display, which they mounted onto a volunteer’s hand.
At low voltages, the stretchable display was sufficiently bright to be seen under indoor lighting.
“The bright stretchable display could find a broad range of applications in smart wearables, soft robotics and human-machine interfaces,” they said.
A paper describing the team’s device was published October 4, 2019 in the journal ACS Materials Letters.
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Yunlei Zhou et al. Stretchable High-Permittivity Nanocomposites for Epidermal Alternating-Current Electroluminescent Displays. ACS Materials Lett, published online October 4, 2019; doi: 10.1021/acsmaterialslett.9b00376
