Research Team from Tufts University Improves Metamaterial-Usage With Inkjet Technology

A team of engineers of the Boston Tufts University is turning to inkjet printing technology to improve the established use of metamaterials for mobile, communications and medical devices. As they are more amenable to the resolution of common fabrication methods, these changes might even create new options for the development of metamaterials for visible light.

Symbol image for printed specific electrode patterns for the generation of microwave resonators

Nowadays, technology offers new ways to improve on existing procedures and possibilities across all disciplines. And print helps improve a lot of them! 3D-printed houses, wearable sensors, water purification, printed vegan steaks – printing technologies are successfully employed to solve a lot of problems in the 21st century’s society. A team of engineers at Tufts University now developed new methods to fabricate metamaterials efficiently that can be used to improve mobile, communications, and medical devices.

Impossible Inkjet

Tufts University, a private university in Boston, is known for both their profound liberal arts education and their focus on research, so it comes as no surprise that a team of engineers from their silklab has delivered impressive findings for the international science community once again. They have been working to develop an inexpensive, scalable method to make metamaterials that are able to manipulate microwave energy. Their methods have the potential to significantly boost signal-sensitivity and transmission power of telecommunications, GPS and radar as well mobile and medical devices and are widely accessible and scalable by taking advantage of well-established and low-cost inkjet printing technology. The metamaterials created in their study can be applied to large conformable surfaces or even interface with biological environments. The thin film organic polymer having a biocompatible nature makes their metamaterials extraordinarily suited for medical communications appliances, possibly enabling the incorporation of enzyme-coupled sensors, while also being used in or on the human body thanks to their inherent flexibility.

ℹ Impossible Materials

Metamaterials, also known as “impossible materials” are artificially engineered constructs exhibiting properties that cannot be found in naturally occuring materials. They are usually created by assembling structures smaller than the wavelengths of the energy they are supposed to influence in repeating patterns, with multiple elements of composite materials like metals and plastics. The properties of the metamaterials are therefore not based on their individual components but rather gain them from the newly compiled structures, specifically designed to possess smart properties such as blocking, absorbing, enhancing or bending waves in order to extend the benefits of their base materials. In theory, these metamaterials are therefore able to also concentrate the energy into specifically created focused beams, have chameleon-like abilities that allow a reconfiguration of their absorption or transmission of different frequency ranges, or even bend energy around objects to make them appear invisible. The two-dimensional counterparts of metamaterials are called meta-surfaces.

Impossible Devices

For their metamaterials, Tufts’ engineers employed a substrate of conducting polymers which were then imprinted with specific patterns of electrodes to create microwave resonators. These resonators are used in communications devices that can help filter select frequencies of energy that are then either absorbed or transmitted. Their finished, inkjet-printed materials can be electrically tuned to adjust the range of frequencies the modulators can filter.

„We demonstrated the ability to electrically tune the properties of meta-surfaces and meta-devices operating in the microwave region of the electromagnetic spectrum. Our work represents a promising step compared to current meta-device technologies, which largely depend on complex and costly materials and fabrication processes,“

said Fiorenzo Omenetto, Frank C. Doble Professor of Engineering at Tufts University School of Engineering and director of the Tufts Silklab as well as corresponding author of the study, to Nature Electronics. The research relies solely on thin-film materials that can be processed and deposited through mass-scalable techniques like printing and coating.

Impossible Prospects

Giorgio Bonacchini, first author of the groundbreaking study, is hoping their proof-of-concept device is only the beginning and will “encourage further explorations of how organic electronic materials and devices can be successfully used in reconfigurable metamaterials and meta-surfaces across the entire electromagnetic spectrum.“ He wants his research to be the basis of testing the limits of metamaterials operating at higher frequencies of the electromagnetic spectrum, enabling the development of metamaterials for visible lights, which is working on a nanometer scale wavelength instead of the centimeter-scale wavelengths of microwave energy. This technology is still in its early stages due to the technical challenges of making tiny arrays of substructures at that scale at the moment, a problem that could be solved by using the imprinted metamaterials, as they are more amenable to the resolution of common fabrication methods.

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