Spray-on antennas unlock communication of the future
Posted by admin on 21st September 2018

Hear the word “antenna” and you might think about rabbit ears on the top of an old TV or the wire that picks up radio signals for a car. But an antenna can be much smaller – even invisible. No matter its shape or size, an antenna is crucial for communication, transmitting and receiving radio signals between devices. As portable electronics become increasingly common, antennas must, too.

Wearable monitors, flexible smart clothes, industrial sensors and medical sensors will be much more effective if their antennas are lightweight and flexible – and possibly even transparent. We and our collaborators have developed a type of material that offers many more options for connecting antennas to devices – including spray-painting them on walls or clothes.

Our materials science lab focuses on nanomaterials, which are more than 100,000 times thinner than a human hair. In 2011, researchers in the Drexel University Materials Science and Engineering Department developed a way to combine metals with carbon or nitrogen atoms to create a material that’s a few atoms thick, very strong and good at conducting electricity. We call these materials MXenes (pronounced “maksens”), and we can make them with different metals – including titanium, molybdenum, vanadium and niobium.

Our most recent work has identified that mixing MXenes with water lets us spray antennas on any surface, including a brick wall or a glass window – and even use an inkjet to print an antenna on paper. This creates new opportunities for smaller, lighter, more flexible antennas to accompany devices that are also being made from more varied and versatile materials.

Antennas aren’t quite everywhere – yet

Researcher Asia Sarycheva holds up an MXene antenna.
Drexel University Nanomaterials Group, CC BY-ND

Smart watches and electronic car key fobs might seem advanced, but researchers are working on many more options, including hospital gowns that can sense patients’ heart and breathing rates, and stitches that monitor healing after surgery. They’ll need antennas too – which are sterile, flexible, strong and even machine-washable.

Another type of antenna is making its way into the world, too. Many credit and debit cards, as well as U.S. passports, contain what are called RFID tags, tiny electronic chips that carry identifying information and transmit them to sensors that validate transactions or certify the identity of the document’s carrier.

RFID tags are even more commonly used in industry, tracking components in manufacturing processes, individual boxes and containers in large shipments and even controlling workers’ access to specific areas of an office or factory.

A wide range of uses

Since Drexel’s 2011 discovery of MXenes, researchers around the world have been testing out how they work in a variety of tasks. Some early successes have included energy storage devices, electromagnetic interference shielding, water filtration, chemical sensing, structural reinforcement, cancer treatment and gas separation.