The elastic material made from liquid metal that is impervious to both gases and liquids. Image: Michael Dickey, NC State University.
The elastic material made from liquid metal that is impervious to both gases and liquids. Image: Michael Dickey, NC State University.

An international team of researchers has developed a technique for using liquid metal to create an elastic material that is impervious to both gases and liquids. Potential applications for this material include as packaging for high-value technologies that require protection from gases, such as flexible batteries.

“This is an important step because there has long been a trade-off between elasticity and being impervious to gases,” says Michael Dickey, professor of chemical and biomolecular engineering at North Carolina State University and co-corresponding author of a paper on this work in Science.

“Basically, things that were good at keeping gases out tended to be hard and stiff. And things that offered elasticity allowed gases to seep through. We’ve come up with something that offers the desired elasticity while keeping gases out.”

The new technique makes use of a eutectic alloy of gallium and indium called EGaIn. Eutectic means the alloy has a melting point that is lower than its constituent parts; in this case, EGaIn is liquid at room temperature. The researchers created a thin film of EGaIn, and encased it in an elastic polymer. The interior surface of the polymer was studded with microscale glass beads, which prevented the liquid film of EGaIn from pooling. The end result is essentially an elastic bag or sheath lined with liquid metal, which does not allow gases or liquids in or out.

The researchers tested the effectiveness of the new material by assessing the extent to which it allowed liquid contents to evaporate, as well as the extent to which it allowed oxygen to leak out of a sealed container made of the material.

“We found that there was no measurable loss of either liquid or oxygen for the new material,” says Tao Deng, a professor at Shanghai Jiao Tong University in China and another co-corresponding author of the paper.

The researchers are also conscious of the costs associated with manufacturing the new material. “The liquid metals themselves are fairly expensive,” Deng says. “However, we’re optimistic that we can optimize the technique – for example, making the EGaIn film thinner – in order to reduce the cost. At the moment, a single package would cost a few dollars, but we did not attempt to optimize for cost so there is a path forward to drive cost down.”

The researchers are currently exploring testing options for determining whether the material is actually an even more effective barrier than they’ve been able to show so far. “Basically, we reached the limit of the testing equipment that we had available,” Dickey says.

“We’re also looking for industry partners to explore potential applications for this work. Flexible batteries for use with soft electronics is one obvious application, but other devices that either use liquids or are sensitive to oxygen will benefit from this technology.”

This story is adapted from material from North Carolina State University, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.