Smartphones or GPS navigators that can be rolled up and stuffed into the back pocket of your Diesel jeans are inching closer to reality.
Advancements in display technology have created flexible displays that could be available commercially in about two years. Now, a new breakthrough suggests another critical component for most gadgets — antennas — are set to get more twisty than a pretzel.
Using a new combination of alloys, researchers have created shape-shifting antennas that could be embedded into materials such as textiles, bandages and bendable displays to bring in a new generation of flexible devices.
“The antennas can be bent, stretched, cut and twisted and [yet] will return to its original shape,” says Michael Dickey, assistant professor of chemical and biomolecular engineering at North Carolina State University and co-author of the research.
Antennas are a part of most major consumer electronic devices from cellphones to GPS systems. Traditionally they are made from copper by milling or etching rigid sheets of copper into a shape that can be used for a single purpose. While copper makes for efficient antennas, it is not well suited for flexible electronics because it fatigues when bent repeatedly and can even break completely.
That’s why the researchers started looking at alternatives to copper. They decided to make new antennas by injecting an alloy of the metals gallium and indium into very small channels — the width of a human hair. Both metals remain in liquid form at room temperature.
The microchannels that they are injected into are straw-like but could be any shape, say the researchers. Once the alloy has filled the channel, the surface of it oxidizes, creating a skin that holds the alloy in place while allowing it to retain its flexibility.
“This is particularly attractive for antennas, because the frequency of an antenna is determined by its shape,” says Dickey. “So you can tune these antennas by stretching them.”
The antennas radiate with 90 percent efficiency, but they are likely to be more expensive than current copper-based products. That’s why the technology could find its first application in military equipment, says Dickey.
Another application could be in construction. For instance, the antenna in a flexible silicone shell could be attached to a bridge. As the bridge expands and contracts, it would stretch the antenna and change its frequency. This could provide engineers information about the condition of the bridge.
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Photo: Flexible antenna/NCSU
