Flexible, stretchable LEDs based on quantum dots can be manufactured in ultrathin sheets and applied to human skin like a sticker. These low-voltage "electronic tattoos" could be the next step in wearable technologies, according to researchers from the Institute for Basic Science and Seoul National University in South Korea. Quantum dot light-emitting diodes (QLEDs) can be printed on films that can curve, bend and stretch. Courtesy of the Institute for Basic Science. Called QLEDs, the colloidal quantum dot light-emitting diode arrays are made using the intaglio transfer printing technique. This allows the alignment of red, green and blue pixels with high resolutions, up to 2460 pixels per inch, which the researchers said is superior to other displays, including the latest smartphones. The printing technique is readily scalable over large area, said the researchers. Electroluminescence performance was 14,000 cdm-2 at 7 V, the best reported to date, the researchers said. The film can be applied to curved surfaces and can be stretched or wrinkled, making it suitable for application on human skin. The technology creates new possibilities for integrating full-color HD displays in wearable electronics, according to the researchers. The research was published in Nature Communications (doi: 10.1038/ncomms8149). For more information, visit www.ibs.re.kr.