Liquid electronics breakthrough could help robots reassemble on the go

6 Nov 2017

Image: Peyker/Shutterstock

In an effort to create more mouldable computers, a team of researchers has managed to build transistors using liquid metal.

While it is hard not to draw comparisons with the T-1000 Terminator that could liquefy itself at a moment’s notice, a new breakthrough in fluidic electronics could actually see robots reassemble themselves on the move.

In a paper published to the journal Advanced Science, a team of engineers from Carnegie Mellon University has revealed a fully functional liquid transistor, the electrical switch that acts as the brainpower behind every electronic device.

Started with circuits

The team’s research began after it managed to make flexible circuits using a special metal alloy, which, at room temperature, exists as a liquid.

Made from a mixture of the metals indium and gallium – a non-toxic alternative to mercury – the liquid metal can be infused into rubber, creating circuits that could be moulded into a shape almost identical to human skin.

This then led the team to determine that a liquid transistor was just as possible by figuring out how to create an opening, and closing a connection between two liquid metal droplets.

The researchers explained that when a voltage drop is applied in one direction, the droplets move towards each other and coalesce to form a metallic bridge for conducting electricity.

When the voltage is reversed to come from the opposite direction, the droplets spontaneously break apart and turn the switch to open.

With just a small amount of voltage and quickly alternating between an open and closed switch state, the team demonstrated a conventional transistor.

Using a process in physics known as the Plateau-Rayleigh instability, which turns a slow stream into drops of liquid, the team was able to drive a separation between droplets of the metal alloy and thus, the liquid transistor was created.

Reassembling robots

The potential for liquid transistors is endless because if materials could be programmed to change shape, they could potentially change their function or even reconfigure themselves to bypass damage in extreme environments.

“It could be on a structure that’s undergoing some very large physical deformations, like a flying robot that mimics the properties of a bird,” explained Carmel Majidi, who was involved in the research.

“When it spreads its wings, you want the circuitry on the wings to also deform and reconfigure so that they remain operational, or support some new kind of electrical functionality.”

There has even been a suggestion that search-and-rescue robots could use it to reassemble new parts after becoming damaged, just as the T-1000 did in Terminator 2.

Colm Gorey was a senior journalist with Silicon Republic