Tuning in: Silvery wires of a liquid-metal alloy, encased in a polymer, form an antenna that still works after being twisted.
Injecting liquid metal into polymer molds produces efficient antennas that can twist and stretch
Source: “Reversibly Deformable and Mechanically Tunable Fluidic Antennas”
Michael D. Dickey et al.
Advanced Functional Materials 19: 3632-3637
Results: Engineers at North Carolina State University created a flexible yet efficient antenna using a liquid metal, a gallium-indium alloy. The antenna is as efficient as a standard copper antenna, transmitting over a broad frequency range at about 90 percent efficiency. It remains functional even when it is twisted, folded, or stretched to 40 percent beyond its normal length.
Why it matters: The antenna could make it easier to send and receive data from flexible electronics, such as sensors incorporated into clothing, electronic paper, or implantable biomedical devices. The radio frequencies it responds to change as it stretches, which means that it could be embedded in machinery or in a concrete structure such as a bridge to monitor it for strain over time.
Methods: The researchers poured liquid polydimethylsiloxane (PDMS) into a mold. Once cured, the PDMS formed a pliable structure with a hollow channel inside. They injected the gallium-indium mixture into the channel and sealed it, creating a simple dipole antenna (like the “rabbit ears” used for analog TV reception).
Next steps: The researchers are building and testing liquid-metal antennas in other shapes, such as the loops, helices, and patches more commonly used in devices like cell phones and GPS transceivers. They are also evaluating other polymers, since PDMS might interfere with the efficiency of these differently shaped antennas.