Modern antennas are made from copper or other metals, but there are limitations to how far they can be bent — and how often — before they break completely.
North Carolina State University scientists have created antennas using an alloy that can be bent, stretched and twisted — after which they will return to their original shape.
The researchers make the new antennas by injecting an alloy made from gallium and indium — which remains in liquid form at room temperature — into very small channels the width of a human hair. The channels are hollow. like a straw, with openings at either end, but can be any shape. Once the alloy has filled the channel, the surface of the alloy oxidises, creating a skin that holds the alloy in place while allowing it to retain its liquid properties.
Because the alloy remains a liquid, it takes on the mechanical properties of the material encasing it, according to Dr Michael Dickey, assistant professor of chemical and biomolecular engineering at NC State.
For example, the researchers injected the alloy into elastic silicone channels, creating wire-like antennas that are incredibly resilient and that can be manipulated into a variety of shapes. Dickey said: ‘This flexibility is particularly attractive for antennas because the frequency of an antenna is determined by its shape. So you can tune these antennas by stretching them.’
While the alloy makes an effective antenna that could be used in a variety of existing electronic devices, its durability and flexibility also open the door to a host of new applications. For example, an antenna in a flexible silicone shell could be used to monitor civil construction, such as bridges. As the bridge expands and contracts, it would stretch the antenna, changing its frequency and providing civil engineers with information wirelessly about the condition of the bridge.
Flexibility and durability are also ideal characteristics for military equipment, since the antenna could be folded or rolled up into a small package for deployment and then unfolded again without any impact on its function.
Dickey believes these new applications are the most likely uses for the antennas, since the alloy is more expensive than the copper typically used in most consumer electronics that contain antennas.
Dickey’s lab is performing further research under a US National Science Foundation grant to better understand the alloy’s properties and a means of using it to create useful devices.