[Image above] Credit: Drexel University, YouTube
Now that smartphones have given everyone immediate access to anyone or anything within seconds via the internet, the next logical step is connecting stuff to each other, i.e., the Internet of Things (IoT). Last year, Gartner predicted that 8.4 billion things would be connected by the end of 2017. They also predicted that businesses would employ 3.1 billion connected things that year.
That’s a lot of things.
And while we take all this connectivity for granted, the unsung hero here is the lowly antenna. If it were not for Heinrich Hertz and Guglielmo Marconi, we would have never been able to enjoy the experience of listening to the radio, watching TV, or communicating with each other through our mobile devices.
Researchers at Drexel University are working to take IoT technology to new frontiers. Led by Distinguished University and Bach professor of Materials Science and Engineering in the College of Engineering, and director of the A.J. Drexel Nanomaterials Institute, Yury Gogotsi, the team created a way to “spray-paint” very thin antennas on to a flexible surface. The antennas perform just as well as those found in mobile devices, routers, and portable transducers, according to a Drexel University news release.
One challenge researchers have faced has been in the area of wearable technology, which includes fabrics and other flexible materials that could be connected to the internet. Because antennas are typically made out of metal, it had been virtually impossible to integrate them into thin materials such as fabrics. Another problem is insufficient skin depth—the thickness of material where the electric current controlling the radio waves flows—which limits the fabrication of thin antennas, according to the paper.
“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,” Gogotsi explains in the release.
To make thin flexible antennas, Gogotsi and his team used MXenes, a group of two-dimensional materials consisting of transition metal carbides and nitrides. They wanted a two-dimensional material that was a “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,” according to Gogotsi. MXenes, discovered by Drexel researchers seven years ago, were the most appropriate materials, as they have already been used in a number of applications, including energy storage, water purification, and as antibacterial agents.
In this particular research, the scientists dissolved the MXene titanium carbide in water to create a type of conductive “paint.” They tested the paint on a rough cellulose paper substrate as well as a smooth one (polyethylene terephthalate). After comparing the painted antennas with others made from graphene, silver ink, and carbon nanotubes, they found that the transmission quality of the MXene-sprayed antennas was 50 times better than graphene and 300 times better than those made of silver ink, for example. They also performed just as well as traditional thicker antennas made of metal.
“The MXene antenna not only outperformed the macro and micro world of metal antennas, we went beyond the performance of available nanomaterial antennas, while keeping the antenna thickness very low,” research assistant professor in A.J. Drexel Nanomaterials Institute Babak Anasori says in the Drexel release.
“This is a very exciting finding because there is a lot of potential for this type of technology,” professor of electrical and computer engineering in the College of Engineering and director of the Drexel Wireless Systems Lab Kapil Dandekar adds. “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 open-access paper, published in Science Advances is “2D titanium carbide (MXene) for wireless communication” (DOI: 10.1126/sciadv.aau0920).
Watch the video below to learn more about this promising research.