Duke University has been responsible for several interesting developments related to 3D printing lately, and a lot of those developments have been related to new 3D printing materials and methods. A hydrogel that mimics the meniscus (I love saying that out loud), a technique that allows for the 3D printing of flexible digital storage…and now, Duke researchers are setting their sights on our devices. Wi-Fi, Bluetooth, wireless sensing and communications – they could all be advanced thanks to the 3D printed electromagnetic metamaterials Duke University has developed.
3D printed metamaterials are an area of interest to many scientists right now. In short, metamaterials are synthetic materials made up of many individually engineered “cells” that work together to produce properties not found in nature. In electromagnetic metamaterials, electromagnetic waves move through the material, triggering each cell to react in a specific way to control how the wave behaves. Until now, the fabrication of electromagnetic metamaterials has been mostly relegated to 2D circuit boards, limiting what they can do and how effective they are. But materials scientists and chemists at Duke have now found a way to 3D print electromagnetic metamaterials with commercial 3D printers, opening up new applications.
“There are a lot of complicated 3-D metamaterial structures that people have imagined, designed and made in small numbers to prove they could work,” said Steve Cummer, professor of electrical and computer engineering at Duke. “The challenge in transitioning to these more complicated designs has been the manufacturing process. With the ability to do this on a common 3-D printer, anyone can build and test a potential prototype in a matter of hours with relatively little cost.”
To 3D print electromagnetic metamaterials, the right printing material needed to be found. While conductive 3D printer filament does exist, none of it has been strong enough to create viable electromagnetic metamaterials, so Benjamin Wiley, associate professor of chemistry, and postdoctoral researcher Shengrong Ye designed a new copper and polymer composite material called Electrifi, which is currently being sold through their startup, Multi3D.
“Our group is really good at making conductive materials,” said Wiley. “We saw this gap and realized there was a huge unexplored space to be filled and thought we had the experience and knowledge to give it a shot.”
Electrifi is 100 times more conductive than any other filament on the market (and, side note, can be used to 3D print a pretty mean Terminator head). While not as conductive as pure copper, Cummer thought it might be conductive enough to create an electromagnetic metamaterial.
He was right – and not only was Electrifi conductive enough, it interacted with radio waves nearly as strongly as pure copper metamaterials. The 3D geometry of the printed material, meanwhile, interacts with electromagnetic waves 14 times better than 2D materials. What’s more, the researchers were able to 3D print it on a standard Prusa i3 printer.
So what does this mean for real-world applications? There may be a lot of potential for researchers and manufacturers working with radio waves and microwaves. Multiple cubes, each tailored to interact with electromagnetic waves in different ways, can be 3D printed and combined to build new devices.
“We think this could change how the radio frequency industry prototypes new devices in the same way that 3-D printers changed plastic-based designs,” said Wiley. “When you can hand off your designs to other people or exactly copy what somebody else has done in a matter of hours, that really speeds up the design process.”
“We’re now starting to get more aggressive with our metamaterial designs to see how much complexity we can build and how much that might improve performance,” added Cummer. “Many previous designs were complicated to make in large samples. You could do it for a scientific paper once just to show it worked, but you’d never want to do it again. This makes it a lot easier. Everything is on the table now.”
The research was documented in a paper entitled “Microwave metamaterials made by fused deposition 3D printing of a highly conductive copper-based filament,” which you can read here. Authors include Yangbo Xie, Shengrong Ye, Christopher Reyes, Pariya Sithikong, Bogdan-Ioan Popa, Benjamin J. Wiley and Steven A. Cummer. Discuss in the Metamaterials forum at 3DPB.com.
[Source: Duke University]