Researchers develop retractable LED device that can act as a temporary tattoo?

Recently, a team of researchers at Nanjing University reportedly developed a retractable LED device that conveys information and can be attached to human skin and other surfaces. The LED device, which acts like a temporary tattoo, works at low voltage and therefore does not cause harm to the user.

The research reportedly demonstrates a retractable LED device, called an alternating current electroluminescent (ACEL) display, published in the journal ACS Materials Letter in October 2019. The device has a sandwich structure and an electroluminescent layer, which consists of light-emitting microparticles dispersed in a stretchable dielectric material and two flexible silver nanowire electrodes.

This new dielectric material is a ceramic nanoparticle embedded in a rubber polymer, which helps improve the brightness of the device compared to existing ACEL displays. Researchers used this material to create a four-digit stopwatch display, mounted on the hands of volunteers, which provided sufficient brightness under room lighting and low voltage conditions.