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Stretchy, see-through touch panel made from salt-packed hydrogel

Conductive material operates even when pulled to 1,000% its original size

by Bethany Halford
August 21, 2016 | APPEARED IN VOLUME 94, ISSUE 33

Credit: Science
This stretchable, transparent touch panel can be used while it is worn on an arm.
Credit: Science
This stretchable, transparent touch panel can be used while it is worn on an arm.

Touch panels of the future will be a lot like Olympic gymnasts—flexible, stretchy, and resilient. With these properties, touch panels can hug the human form like a leotard, letting us wear electronic devices rather than stick them in our pockets, purses, or briefcases. To date, however, most touch panels have been built with materials that resist stretching, such as indium tin oxide and carbon nanotubes. Researchers at Seoul National University now report a transparent touch panel that can be stretched to 10 times as large as its original area without losing functionality (Science 2016, DOI: 10.1126/science.aaf8810). The superstretchy, see-through device is made of a polyacrylamide hydrogel containing lithium chloride salts. Because of the high water content of the hydrogel, the salt dissolves and acts as an ionic conductor. The scientists who developed the technology, led by Jeong-Yun Sun, made an arm-hugging touch panel and used it for writing and playing video games. Perhaps by the time the 2020 Olympics roll around, we’ll be able to watch gymnasts write notes to their fans during downtime with touch panels embedded in their leotards.

A liquid drop of a sodium-potassium alloy deposited on water starts reacting to produce alkali metal hydroxide, hydrogen, and heat. Solvated electrons turn the drop blue and then black. Subsequently, the drop turns blue again and then red as the drop heats enough for the metals to evaporate. Finally, the metal vapor clears and the drop’s temperature falls as it transformes into transparent molten alkali metal hydroxides before dropping into the water and bursting as the two materials mix.
Credit: Angew. Chem. Int. Ed. Engl.


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