Uninterrupted: New flexible electronics do not shatter, even when punctured
Want a smartphone that stretches, gets damaged and still doesn’t miss a call?
A team of researchers at Virginia Tech from the Department of Mechanical Engineering and the Macromolecules Innovation Institute have created a new kind of soft electronics, paving the way for self-healing, reconfigurable and recyclable devices. These skin-shaped circuits are soft and stretchable, suffer a lot of damage under load without loss of electrical conductivity, and can be recycled to generate new circuits at the end of a product’s life.
Led by Assistant Professor Michael Bartlett, the team recently published their findings in Communication media, an open access journal of Nature Research.
Current consumer devices, such as phones and laptops, contain rigid materials that use soldered wires that pass through them. The flexible circuit developed by Bartlett’s team replaces these rigid materials with flexible electronic composites and tiny droplets of liquid metal that conduct electricity. These flexible electronic components are part of a burgeoning technological field that gives gadgets a level of durability that would have been impossible just a few years ago.
The liquid metal droplets are initially dispersed in an elastomer, a type of rubbery polymer, as discrete, electrically insulated drops.
âTo create circuits, we introduced a scalable approach through embossing, which allows us to quickly create tunable circuits by selectively connecting droplets,â said postdoctoral researcher and lead author Ravi Tutika. “We can then locally separate the droplets to remake circuits and even completely dissolve the circuits to sever all connections to recycle the materials, then start over.”
Circuits are soft and flexible, like skin, continuing to function even with extreme damage. If a hole is drilled in these circuits, the metal droplets can still transfer energy. Instead of completely cutting off the connection as in the case of a traditional wire, the droplets make new connections around the hole to continue to pass electricity.
The circuits will also stretch without losing their electrical connection, as the team pulled the device to more than 10 times its original length without failure during research.
At the end of a product’s life, metal droplets and rubbery materials can be reprocessed and returned to liquid solution, making them recyclable. From there, they can be remade to start a new life, an approach that offers a path to sustainable electronics.
Although an expandable smartphone has yet to be manufactured, the rapid development in the field holds promise for wearable electronics and soft robotics as well. These emerging technologies require flexible and robust circuits to make the leap into consumer applications.
âWe are excited about our progress and envision these materials as key components for emerging soft technologies,â Bartlett said. “This work comes close to creating flexible circuits that could survive in a variety of real world applications.”
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