Spray-on Antennas a Boost for Wearable Technology

Wednesday, September 26, 2018 @ 04:09 PM gHale

Researchers from Drexel University’s College of Engineering have developed a way to “spray paint” invisibly thin antennas from a type of two-dimensional material called MXene.

The idea of wearables, functional fabrics, and the Internet of Things making connections all over is a great idea in theory, but one of the issues holding back full-scale implementation is creating some type of antenna to get that data out to a collection source.

That issue may soon go away as researchers found a way to install an antenna as easy as applying a can of spray paint.

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There is a method for spraying invisibly thin antennas, made from a type of two-dimensional, metallic material called MXene, that perform as well as those being used in mobile devices, wireless routers and portable transducers, said researchers at Drexel University’s College of Engineering.

“This is a very exciting finding because there is a lot of potential for this type of technology,” said Kapil Dandekar, PhD, a professor of Electrical and Computer Engineering in the College of Engineering, who directs the Drexel Wireless Systems Lab, and was a co-author of the research. “The ability to spray an antenna on a flexible substrate or make it optically transparent means that we could have a lot of new places to set up networks – there are new applications and new ways of collecting data that we can’t even imagine at the moment.”

The researchers, from the College’s Department of Materials Science and Engineering, report the MXene titanium carbide can dissolve in water to create an ink or paint. The exceptional conductivity of the material enables it to transmit and direct radio waves, even when it’s applied in a very thin coating. 

“We found that even transparent antennas with thicknesses of tens of nanometers were able to communicate efficiently,” said Asia Sarycheva, a doctoral candidate in the A.J. Drexel Nanomaterials Institute and Materials Science and Engineering Department. “By increasing the thickness up to 8 microns, the performance of MXene antenna achieved 98 percent of its predicted maximum value.”

Preserving transmission quality in a form this thin is significant because it would allow antennas to easily be embedded – literally, sprayed on – in a wide variety of objects and surfaces without adding additional weight or circuitry or requiring a certain level of rigidity. 

Seamless Integration
“This technology could enable the truly seamless integration of antennas with everyday objects which will be critical for the emerging Internet of Things,” Dandekar said. “Researchers have done a lot of work with non-traditional materials trying to figure out where manufacturing technology meets system needs, but this technology could make it a lot easier to answer some of the difficult questions we’ve been working on for years.”

Initial testing of the sprayed antennas suggest they can perform with the same range of quality as current antennas, which are made from familiar metals, like gold, silver, copper and aluminum, but are much thicker than MXene antennas. Making antennas smaller and lighter has long been a goal of materials scientists and electrical engineers, so this discovery is a sizeable step forward in terms of reducing their footprint as well as broadening their application. 

“Current fabrication methods of metals cannot make antennas thin enough and applicable to any surface, in spite of decades of research and development to improve the performance of metal antennas,” said Yury Gogotsi, PhD, Distinguished University and Bach professor of Materials Science and Engineering in the College of Engineering, and Director of the A.J. Drexel Nanomaterials Institute, who initiated and led the project. “We were looking for two-dimensional nanomaterials, which have sheet thickness about hundred thousand times thinner than a human hair; just a few atoms across, and can self-assemble into conductive films upon deposition on any surface. Therefore, we selected MXene, which is a two-dimensional titanium carbide material, that is stronger than metals and is metallically conductive, as a candidate for ultra-thin antennas.” 

Drexel researchers discovered the family of MXene materials in 2011 and have been gaining an understanding of their properties, and considering their possible applications, ever since. The layered two-dimensional material, which is made by wet chemical processing, has already shown potential in energy storage devices, electromagnetic shielding, water filtration, chemical sensing, structural reinforcement and gas separation. 



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