Inkjet-Printed Metal May Help Create Wearable Electronics and Soft Robotics

Imagine having flexible electronics rather than the hard plastic ones of today. This idea may soon become a reality with the help of inkjet-printing technology. Scientists have found that elastic technologies could make possible a new class of pliable robots and stretchable garments that could be used to interact with computers.

"We want to create stretchable electronics that might be compatible with soft machines, such as robots that need to squeeze through small spaces, or wearable technologies that aren't restrictive of motion," said Rebecca Kramer, one of the researchers, in a news release. "Conductors made form liquid metal can stretch and deform without breaking."

The question is: how to make these electronics? A new potential manufacturing approach focuses on harnessing inkjet printing to create devices made of liquid allows. This process allows scientists to print flexible and stretchable conductors onto anything, including elastic materials and fabrics.

"Liquid metal in its native form is not inkjet-able," said Kramer. "So what we do is create liquid metal nanoparticles that are small enough to pass through an inkjet nozzle. Sonicating liquid metal in a carrier solvent, such as ethanol, both creates the nanoparticles and disperses them in the solvent. Then we can print the ink onto any substrate. The ethanol evaporates away so we are just left with liquid metal nanoparticles on a surface."

After printing, the nanoparticles must be rejoined by applying light pressure, which renders the material conductive. This approach makes it possible to select which portions to activate depending on particular designs. This suggests that a blank film might be manufactured for a multitude of potential applications.

The researchers plan to explore how the interaction between the ink and the surface being printed on might be conducive to the production of specific types of devices. They also plan to study and model how individual particles rupture when pressure Is applied, which could provide information for the manufacture of ultrathin traces and new types of sensors.

The findings are published in the journal Advanced Materials.

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