Engineers enable active cooling and RF communications with new 3D printed metamaterial

A team of U.S. researchers has used 3D printing to create a novel, highly configurable metamaterial with modifiable thermal and electromagnetic properties.

The engineers, led by North Carolina State University PhD student Urmi Devi, state that they drew inspiration from the vascular networks found in living organisms. By 3D printing networks of tiny vein-like hollow tubes, the team found that it could control several characteristics of the composite metamaterial when pumping different fluids through the vasculature.

The bioinspired innovation was 3D printed using structural epoxy reinforced with glass fibers, which is referred to as ‘vascularized fiberglass’. According to Jason Patrick, corresponding author of the study, the reconfigurability of the metamaterial makes it multifunctional, with potential applications in active cooling for microprocessors, aircraft, and buildings, as well as on-the-fly tunable communications devices.

“Fiber-reinforced composites are already in widespread use,” said Patrick. “What we’re doing is making material advancements and leveraging 3D printing to create a new class of multifunctional and reconfigurable metamaterials that has real potential for scalable, structural implementation and shouldn’t be prohibitively expensive.”

The metamaterial's EM properties can be modified with a liquid metal alloy, while its thermal properties can be modified by running water through it. Image via NC State University.
The metamaterial’s EM properties can be modified with a liquid metal alloy, while its thermal properties can be modified by running water through it. Image via NC State University.

3D printing-enabled metamaterials

The versatility of the metamaterial can ultimately be attributed to the design freedom granted by additive manufacturing. The technology allowed the engineers to 3D print highly complex networks of tubes – the microvasculature – in a wide range of geometries and sizes. Since the metamaterial relies on readily available composite fabrication processes, it should also be cost-effective to produce.

During the experiment, the U.S. researchers ran a room-temperature liquid alloy of gallium and indium through the network, which allowed them to control its electromagnetic properties. Specifically, by modifying the vasculature’s orientation, spacing, and the volume of conductive liquid metal inside, the team could closely control how the metamaterial filtered out specific electromagnetic waves in the radio frequency spectrum. This holds great potential for tunable communications systems capable of hopping from one part of the spectrum to another on-demand.

Kurt Schab, a co-author of the paper, adds, “The ability to dynamically reconfigure electromagnetic behavior is really valuable, particularly in applications where size, weight, and power constraints highly incentivize the use of devices which can perform multiple communication and sensing roles within a system.”

The experimental setup for testing the EM properties of the 3D printed metamaterial. Image via NC State University.
The experimental setup for testing the EM properties of the 3D printed metamaterial. Image via NC State University.

Applications in active cooling

By simply circulating water through the vasculature network, the engineers demonstrated that they could also closely control the metamaterial’s thermal properties. This is expected to enable advanced active cooling systems in devices such as hypersonic aircraft, microprocessor systems, and electric vehicles.

The batteries of electric vehicles, in particular, currently rely on aluminum fins with simple microchannels for their cooling. The 3D printed metamaterial is expected to be just as effective at dissipating heat, all while being significantly lighter with more complex, optimized channel architectures.

“We clearly have some applications in mind for this metamaterial, but there are certainly applications we haven’t thought of,” adds Patrick. “We are open to working with folks who have fresh ideas on how we might be able to make further use of this novel material.”

Further details of the study can be found in the paper titled ‘A Microvascular-Based Multifunctional and Reconfigurable Metamaterial’. It is co-authored by Jason Patrick, Urmi Devi, Kurt Schab, et al.

Innovations in 3D printed materials are a major contributor to the advancement of functional additive manufacturing applications. Just last month, scientists from Nanyang Technological University (NTU) Singapore and the California Institute of Technology (Caltech) 3D printed a flexible chain mail-inspired fabric that can stiffen on demand. 3D printed from nylon plastic polymer octahedrons that interlock with each other, the fabric can turn into a rigid structure that is 25 times stiffer than its relaxed form.

Elsewhere, scientists from the Eindhoven University of Technology (TUE) recently broke new ground with the development of a novel color-changing liquid crystal ink that is compatible with 3D printing technology. The team believes its work could have major implications for applications such as decorative lighting, soft wearable sensors for health monitoring, and even augmented reality optics.

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Featured image shows the 3D printed metamaterial. Image via NC State University.