Image of light-emitting device
A stretchable light-emitting device becomes an epidermal stopwatch. (Credit: Adapted from ACS Materials Letters 2019, DOI: 10.1021/acsmaterialslett.9b00376)

Scientists have developed stretchable light-emitting devices called alternating-current electroluminescent (ACEL) displays that can be stuck on skin or other surfaces like a temporary tattoo. A new advancement means the devices can operate at lower voltages than previous versions and thus are 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.

They 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, the researchers say.

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