Johns Hopkins APL demonstrates temperature-responsive antenna using 3D-printed shape memory alloys

Researchers at Johns Hopkins Applied Physics Laboratory have documented the successful fabrication of a shape-morphing antenna using additive manufacturing of modified nitinol, demonstrating temperature-controlled transformation between flat spiral and conical configurations. The researchers describe the work, published in ACS Applied Engineering Materials, as an empirical validation of shape memory alloy (SMA) application in reconfigurable RF systems. The paper describes the technology as a”double spiral antenna capable of actuating through thermal response alone” that can “actuate from a flat spiral antenna to an extended conical spiral antenna.”

“We have demonstrated a single antenna element that can morph into an entirely different shape with no use of motors, only thermal actuation,” the authors write in the introduction of the ACS Applied Engineering Materials article

The technology has a sci-fi connection. Specifically, electrical engineer Jennifer Hollenbeck reported finding inspiration from “The Expanse” series, where alien technology is organic and shape-shifting. “I have spent my career working with antennas and wrestling with the constraints imposed by their fixed shape,” she said in a press release. “I knew APL had the expertise to create something different.”

The research team’s approach combines modified nickel-titanium ratios in nitinol with specialized additive manufacturing parameters to achieve two-way shape memory behavior. The press release explains that the researchers overcame several key technical challenges, including the development of a specialized power delivery system for controlled heating and optimization of 3D printing parameters for the modified alloy composition.

Technical capabilities and roadmap

The team demonstrated basic shape-shifting functionality between flat and conical spiral configurations, with temperature-based actuation. Projected applications span military communications, telecommunications, and space systems. The researchers have filed patent applications for the core technology and several supporting technologies, including the heating system and control methodology.

The research team identified several key development priorities in the paper, including the optimization of additive manufacturing parameters, such as achieving an optimal energy density of 51 J/mm³ using the EOS M290 selective laser melting (SLM) system with a 1070 nm, 400 W ytterbium fiber laser. Additionally, they are focusing on the investigation of material variants to tailor actuation temperatures, which currently range from approximately 30°C to 55°C, allowing for precise thermal control. Technical challenges remain in scaling production processes to meet industrial demands, ensuring consistent performance across multiple manufacturing runs, and validating long-term reliability of the shape-morphing antennas under diverse environmental conditions. In addition, further work is needed to quantify RF performance across the operational frequency range of 4 GHz to 11 GHz under various actuation states and to establish durability metrics through extensive testing to ensure the antennas maintain their reconfigurable capabilities over extended periods.

In the conclusion of their paper, the researchers note that “AM-SMA antennas are a paradigm shifting technology and deserve serious consideration in improving numerous conventional antenna designs.”