Metamaterials Made through Inkjet Printing

Tufts University engineers have found new methods for more effectively fabricating materials that interact with microwave energy in unexpected ways, which might have ramifications for telecommunications, GPS, radar, mobile devices, and medical equipment. Metamaterials are also known as “impossible materials” because they have the ability to bend energy around objects to make them appear invisible, concentrate energy transmission into focused beams, and have chameleon-like abilities to reconfigure their absorption or transmission of different frequency ranges.

Obtaining metamaterials and how they are beneficial for the industry

The metamaterials are created using low-cost inkjet printing, making the method widely accessible and scalable while also providing benefits such as the ability to be applied to large conformable surfaces or interface with a biological environment, according to the research published today in Nature Electronics. It’s also the first time that organic polymers have been utilized to electrically “tune” metamaterial characteristics.

Electromagnetic metamaterials and meta-surfaces, which are their two-dimensional equivalents, are composite structures that interact with electromagnetic waves in unusual ways. The materials are made up of microscopic structures that are meticulously organized in repeating patterns and are smaller than the wavelengths of the energy they affect. The ordered structures have unique wave interaction capabilities, allowing the creation of unusual mirrors, lenses, and filters that can block, amplify, reflect, transmit, or bend waves in ways that ordinary materials can’t.

Modern day examples in which metamaterials would prove useful

Tufts engineers created their metamaterials by inkjet printing precise patterns of electrodes onto conducting polymers as a substrate to generate microwave resonators. Resonators are critical components in communications equipment that assist filter certain frequencies of energy that are absorbed or sent according to California News Times. The modulators may filter a wider spectrum of frequencies by electrically tuning the printed components.

Metamaterial devices that operate in the microwave spectrum might find broad use in telecommunications, GPS, radar, and mobile devices, where metamaterials can greatly improve signal sensitivity and transmission power. The biocompatible characteristics of the thin film organic polymer might allow the insertion of enzyme-coupled sensors, while its intrinsic flexibility could allow devices to be fashioned into conformable surfaces suited for usage on or in the body.

Fiorenzo Omenetto, Frank C. Doble Professor of Engineering at Tufts University School of Engineering, director of the Tufts Silklab where the materials were created, and corresponding author of the study, demonstrated the ability to electrically tune the properties of meta-surfaces and meta-devices operating in the microwave region of the electromagnetic spectrum. They continue to explain how “In comparison to existing meta-device technologies, which rely heavily on complicated and expensive materials and fabrication procedures, our study marks a potential step forward.”

Studies are still being done to better prepare use for the future

Reported on TuftsNow, the study team’s tuning method is solely based on thin-film materials that can be produced and coated on a variety of substrates using mass-scalable processes like printing and coating. Because the scientists were able to adjust the electrical characteristics of the substrate polymers, they were able to operate the devices across a far broader range of microwave energy and frequencies (of around 5 GHz) than was previously thought conceivable with non-meta materials, being about 0.1GHz.

Due to the technical challenges of making tiny arrays of substructures at that scale, development of metamaterials for visible light, which has nanometer-scale wavelengths, is still in its early stages, but metamaterials for microwave energy, which has centimeter-scale wavelengths, are more amenable to the resolution of common fabrication methods. The scientists speculate that the production process they describe, which involves inkjet printing and other types of deposition on thin film conducting polymers, may be used to begin testing the limitations of metamaterials that operate at higher frequencies of the electromagnetic spectrum.

“This research is, potentially, only the beginning,” said Giorgio Bonacchini former post-doctoral fellow in Omenetto’s lab in a ScienceDaily article. “Hopefully, our proof-of-concept device 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.”