The new antennas are made by injecting a eutectic alloy of Ga and In, which remains in liquid form at room temperature, into very small channels the width of a human hair. The channels are hollow with openings at either end but can be any shape. Once the alloy has filled the channel, the surface of the alloy oxidizes, creating a “skin” that holds the alloy in place while allowing it to retain its liquid properties.
For example, the researchers injected the alloy into elastic silicone channels, creating wirelike antennas that are incredibly resilient and that can be manipulated into a variety of shapes. Since the frequency is determined by the antennas size/shape, it can be tuned by stretching it.
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 the frequency of the antenna, and providing civil engineers information wirelessly about the condition of the bridge. This had become a priority issue as aging structures have failed in the recent past. There has also been a lot of work done to power the wireless devices with energy harvesting devices so they do not really need servicing.
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. These new applications are the most likely uses for the new antennas, since the alloy is more expensive than the copper typically used in most consumer electronics. So high performance or new applications could utilize this more expensive solution but maybe other liquid metals or alloys could reduce the cost in the future.
Dickey’s lab is performing further research under a National Science Foundation grant to better understand the alloy’s properties and means of utilizing it to create useful devices. The research, “Reversibly Deformable and Mechanically Tunable Fluidic Antennas,” is published in Advanced Functional Materials.