Brett Smith for redOrbit.com – Your Universe Online
Engineers have been working for years to develop liquid metal electronics, and according to a new report in the Journal of Applied Physics, researchers from North Carolina State University have developed a liquid antenna that could revolutionize mobile device technology.
Credit: Jacob Adams
“Mobile device sizes are continuing to shrink and the burgeoning Internet of Things will likely create an enormous demand for small wireless systems,” study author Jacob Adams, an assistant professor of electrical and computer engineering at NCSU, said in a statement. “And as the number of services that a device must be capable of supporting grows, so too will the number of frequency bands over which the antenna and RF front-end must operate. This combination will create a real antenna design challenge for mobile systems because antenna size and operating bandwidth tend to be conflicting tradeoffs.”
Unique properties of liquid metal
Adams noted that liquid metals offer unique properties that make them ideal for use in antenna technology.
“Using a liquid metal—such as eutectic gallium and indium—that can change its shape allows us to modify antenna properties more dramatically than is possible with a fixed conductor,” he said.
In their report, the NCSU team showed how they were able to use electrochemical responses to shorten and stretch out a filament of liquid metal and modify the antenna’s operating frequency. Using a small positive voltage triggers the metal to flow into a one-dimensional capillary, while a small negative voltage causes the metal to shrink from the capillary.
A positive charge “electrochemically deposits an oxide on the surface of the metal that lowers the surface tension, while a negative potential removes the oxide to increase the surface tension,” Adams explained. “We call this ‘electrochemically controlled capillarity,’ which is much like an electrochemical pump for the liquid metal.”
The researchers said their approach significantly boosts the range over which the antenna’s operating frequency can be tuned.
“Our antenna prototype using liquid metal can tune over a range of at least two times greater than systems using electronic switches,” Adams said.
The study team said they plan to further explore the various aspects of tunable liquid metals and even investigate how they might be used to create custom two-dimensional antenna shapes.
“This would enable enormous flexibility in the electromagnetic properties of the antenna and allow a single adaptive antenna to perform many functions,” Adams said.
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