RESEARCH
Unbroken :
New soft electronics don ’ t break , even when punctured
Want a smartphone that stretches , takes damage , and still doesn ’ t miss a call ?
A team of Virginia Tech researchers from the Department of Mechanical Engineering and the Macromolecules Innovation Institute has created a new type of soft electronics , paving the way for devices that are self-healing , reconfigurable , and recyclable . These skin-like circuits are soft and stretchy , sustain numerous damage events under load without losing 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 its findings in Communications Materials , an open access journal from Nature Research .
Current consumer devices , such as phones and laptops , contain rigid materials that use soldered wires running throughout . The soft circuit developed by Bartlett ’ s team replaces these inflexible materials with soft electronic composites and tiny , electricity-conducting liquid metal droplets . These soft electronics are part of a rapidly emerging field of technology 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 electrically insulated , discrete drops .
“ To make circuits , we introduced a scalable approach through embossing , which allows us to rapidly create tunable circuits by selectively connecting droplets ,” postdoctoral researcher and first author Ravi Tutika said . “ We can then locally break the droplets apart to remake circuits and can even completely dissolve the circuits to break all the connections to recycle the materials , and then start back at the beginning .”
The circuits are soft and flexible , like skin , continuing to work even under extreme damage . If a hole is punched in these circuits , the metal droplets can still transfer power . Instead of cutting the connection completely as in the case of a traditional wire , the droplets make new connections around the hole to continue passing electricity .
The circuits will also stretch without losing their electrical connection , as the team pulled the device to over 10 times its original length without failure during the research .
At the end of a product ’ s life , the metal droplets and the rubbery materials can be reprocessed and returned to a liquid solution , effectively making them recyclable . From that point , they can be remade to start a new life , an approach that offers a pathway to sustainable electronics .
While a stretchy smartphone has not yet been made , rapid development in the field also holds promise for wearable electronics and soft robotics . These emerging technologies require soft , robust circuitry to make the leap into consumer applications .
“ We ’ re excited about our progress and envision these materials as key components for emerging soft technologies ,” Bartlett said . “ This work gets closer to creating soft circuitry that could survive in a variety of real-world applications .”
20 VIRGINIA TECH MECHANICAL ENGINEERING • ANNUAL REPORT 2020-2021