New Liquid Metal Coating Could Create Smart Objects

Scientists at the Tsinghua University in China has developed a new malleable liquid metal coating that can be applied to paper to build 3D structures and potentially create smart objects.
 
The coating is inspired by origami, a study showed that paper coated in the metal could conduct heat and electricity and be crafted into origami shaped and re-fold itself. The study was led by Bo Yuan and was published in Cell Reports Physical Science. 
 
Yuan and his team tested an alloy of bismuth, indium, and tin oxide (BilnSn) and an indium/gallium alloy (eGaln) to try and find a liquid metal that could stick without the use of an adhesive. 
 
According to reports, to test the adhesivity of the liquid metal, it was stamped onto paper with different amounts of pressure which did not require much pressure to stick. A self-adhesive origami cube was then created out of the metal-coated paper.
 
When the square was unfolded, the coated paper reportedly could fold itself back into its origami cube form the attracted edges. The shape was then tested by stretching and compression, it remained adjusted. 
 
“We needed to ensure the adhesion of liquid metal to be uniform in large scale on different paper, and to maintain the sustainability of the coating. To solve these problems, we changed pressure applied on the stamp as well as the rubbing speed used on the experiments and finally found the most suitable parameters, which finally achieved fast, large-scale, and stable adhesion,” Yuna said in an interview with Ars Techinca. 
 
Researchers said paper coated in the metal kept its shaped without falling apart making it possible to build 3D structures out of the individual pieces of paper. The coating could then be peeled off, recycled and reused without affecting the properties of the paper substrate. 
 
“Utilizing our method, one can quickly create smart materials with good thermal and electrical conductivity as well as stiffness-tunable ability, which greatly expands material options for soft robots,” Yuan added. “I think that this method may provide a new route for designing space explorers.”
 
The self-adhering liquid metal provides the advantage of providing smart objects and soft robots with a thin lightweight coating that allows them to fit into tight spaces. The team intends to look further into a coating that will not peel off once solidified.
 
Yuan is also considering testing bio-friendly spray paint that will protect the coating in materials that may eventually be used underwater, on human skin, in packaging materials, or in outer space conditions on the moon and other planets.