An international research team led by North Carolina State University has developed a technique using liquid metal to create an elastic material impermeable to gases or liquids. Applications for this material include housings for some high-value technology products such as flexible batteries.
Researchers say that those that are good at gas shielding tend to be tight and rigid. Flexible ones allow gas to escape. Researchers say Materials scientists have long struggled with a compromise between elasticity and air permeability.
The new technology uses a eutectic alloy of gallium and indium (EGaIn), eutectic meaning the alloy has a lower melting point than the constituents, in which case EGAIn is a liquid at room temperature. The researchers made thin films of EGAIn and encapsulated them in a flexible polymer. The inner surface of the polymer is embedded with micro glass beads. This prevents the EGAIn liquid film from coalescing and the end result is a liquid metal lined elastomeric liner that prevents gas or liquid from entering or exiting.
Researchers tested the performance of the new material by evaluating how well the liquid evaporated. and how well it allows oxygen to leak out of sealed containers made of such materials. It was found that there was no measurable loss of fluid or oxygen from the new material.
The researchers say that although liquid metal is relatively expensive, they have kept the cost down by optimizing techniques such as making the EGAIn film thinner, so each package now costs a few dollars.
The research team is seeking industry partners to explore potential applications for this work. Flexible batteries for use in flexible electronics have obvious applications. However, people who use other device liquids or are sensitive to oxygen can also benefit from this technology.
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