New ‘liquid metal’ will let you print circuits on paper, T-shirts, or even leaves

Three Chinese scientists say they’ve found a way to create a metal that’s liquid at room temperatures, can be printed as if it was ink in ordinary, everyday desktop printers, and will adhere to surfaces as diverse and supple as rubber, paper, cotton T-shirts, or a leaf off an oak tree.

Need an RFID T-shirt? A smart magazine?

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The possibilities appear to be endless, as the same material can also be adapted to make a “transparent conductive film,” in other words a see-through electronic circuit, that could be printed on glass or transparent plastic.

The key innovation, MIT Technology Review says, is the alloy of gallium and indium that the scientists discovered. It’s printable at room temperature, while many other printable circuit inks require high temperatures — up to 400 degrees Celsius, or 752 degrees Fahrenheit — which has obvious challenges when you want to print on perishable and delicate surfaces such as paper.

Printing a circuit successfully is great, but not so much when your substrate burns away.

The liquid gallium alloy doesn’t naturally adhere to surfaces well, but as it is sprayed through the air in tiny droplets, it oxidizes, forming a layer that sticks to many materials and textures.

“Different from the former direct writing technology where large surface tension and poor adhesion between the liquid metal and the substrate often impede the flexible printing process, the liquid metal here no longer needs to be pre-oxidized to guarantee its applicability on target substrates,” Qin Zhang, Yunxia Gao, and Jing Liu, the three scientists, write.

The technology behind this innovation is “cheap and simple,” MIT says, adding that “there’s no reason” that it can’t be commercialized quickly.

Which means we could be able to print circuits as well as 3-D products in the comfort of our homes, perhaps in combination, firing the maker revolution with even more fuel.