A team of engineers from Tufts Unversity has advanced material science by developing a novel method of fabricating "impossible materials," or those that behave in unusual ways upon contact with microwave energy through 3D inkjet printing technology.
The new technology could potentially scale up and make the fabrication of these specialized materials more convenient, having significant applications in the fields of telecommunication systems, electronics, navigation, and even medicine. These new inkjet printed materials, known as metamaterials, are often described as impossible materials because they could theoretically bend light around them in a way that makes them "invisible" to the human eye. Furthermore, their behavior allows them to transmit concentrated beams of energy or even reconfigure their properties to adopt waves of varying frequencies.
Researchers present their findings in the article "Reconfigurable microwave metadevices based on organic electrochemical transistors," appearing in the latest Nature Electronics journal.
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Inkjet Printing for Metamaterials
The innovation allows for the fabrication of these impossible materials using low-cost inkjet printing techniques, making them easily accessible and scalable. Furthermore, the technology can be applied to larger conformable surfaces and seamlessly integrated into biological environments. This new study marks the first demonstration of using organic polymers to electrically "tune" the characteristics of these metamaterials.
Electromagnetic metasurfaces and metamaterials, the 2D and 3D forms respectively, constitute composite materials that interact with electromagnetic energy in a unique way, according to a 2015 review on Materials Today. These materials are composed of tiny nanostructures, each smaller than the wavelength of the energy they interact with, arranged in organized and repeating patterns. These patterns allow the nanostructures to create unique interactions with energy, leading to the creation of unconventional mirrors and lenses that can block, reflect, transmit, or bend waves in ways that would otherwise be impossible with conventional materials.
In the new research from Tufts University, the metamaterials are inkjet printed through polymers as a substrate, with the printer embedding certain electrode patterns that become nanostructures serving as resonators for microwave energy. Additionally, it could be electrically tuned to filter only a certain range of frequencies.
A Potentially Game-Changing Technology
Once made available to the public, it could help devices based on metamaterials be used to advance the fields of telecommunications, electronics, navigation, medicine, and other fields where the need for sensitive microwave reception and transmission power plays a crucial role.
For example, in the field of medicine, these inkjet-printed impossible materials could be used for improving devices that require communication since the thin film organic polymer could also allow the integration of enzyme-coupled sensors. Additionally, the material's inherent flexibility means that it could be fabricated to almost any conformable surface that matches the shape requirements for its applications in the human body.
"We demonstrated the ability to electrically tune the properties of meta-surfaces and meta-devices operating in the microwave region of the electromagnetic spectrum," said corresponding author Fiorenzo Omenetto, Frank C. Doble Professor of Engineering at Tufts University School of Engineering and the director of the Tufts Silklab, in the Tufts University press release. "Our work represents a promising step compared to current meta-device technologies, which largely depend on complex and costly materials and fabrication processes."
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