Spray-on antennas may turn objects into connected tech

Scientists have developed a method for spraying invisibly thin antennas on to flexible materials, an advance that could turn a variety of objects and surfaces into seamless Internet of Things.

Researchers from Drexel University in the US used 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.

"This is a very exciting finding because there is a lot of potential for this type of technology," said Kapil Dandekar, a professor at Drexel.

"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," said Dandekar.

The study published in the journal Science Advances shows that the MXene titanium carbide can be dissolved 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 is applied in a very thin coating.

"We found that even transparent antennas with thicknesses of tens of nanometres were able to communicate efficiently," said Asia Sarycheva, a doctoral candidate at Drexel.

"By increasing the thickness up to 8 microns, the performance of MXene antenna achieved 98 percent of its predicted maximum value," said Sarycheva.

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.

"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," he said.

Initial testing of the sprayed antennas suggest that 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 both in terms of reducing their footprint as well as broadening their application.