Drexel 2D material absorbs wavelengths

Much like lead can protect even Superman from the effects of kryptonite, researchers at Drexel University's College of Engineering may have engineered a vanadium-based MXene shield that could render electronic devices impermeable to electromagnetic waves, essentially protecting them from the multitude of frequencies whizzing about our heads every day.

Buzzing, feedback or static are some of the most noticeable manifestations of electromagnetic interference. This is essentially a collision of frequencies generated by electronic devices.

Aside from the sounds, this phenomenon can also diminish the performance of these devices and can even lead to overheating or malfunction if left unchecked.

While researchers and technologists have progressively sought to reduce this problem with each generation of devices, the strategy thus far has generally been to encase vital components with a shielding that just deflects the waves.

According to the Drexel team, however, this is not a sustainable solution.

"Because the number of electronics devices will continue to grow, deflecting the electromagnetic waves they produce is really just a short-term solution," said Yury Gogotsi, professor in the College of Engineering at Drexel. "To truly solve this problem, we need to develop materials that will absorb and dissipate the interference. We believe we have found just such a material."

Advancing research into two-dimensional materials, Drexel has been exploring the possibilities of its MXene 2D material. Discovered more than a decade ago, much like its relative graphene, MXene exhibits properties that are still surprising researchers.

For example, Drexel recently reported earlier this year that it might be possible to use MXene to leach the practically impossible and slippery element mercury from our waters, something that has been increasing in severity over many decades of resource and technological development.

You can read about MXene's mercury adsorption at 2D material to clean up mercury pollution in the August 24, 2022, edition of Metal Tech News.

In its most recent paper, Gogotsi's team reported that combining MXene with a conductive element called vanadium in a polymer solution produces a coating that can absorb electromagnetic waves.

Solution to X-band pollution

While researchers have previously demonstrated that MXenes are highly effective at warding off electromagnetic interference by reflecting it, adding vanadium carbide in a polymer matrix enhances two key characteristics of the material that improve its shielding performance.

According to Drexel, adding vanadium to MXenes' structure – a 2D material that already exhibits extreme durability and corrosion-resistant properties – causes layers of the MXene to form in a sort of electrochemical grid that is perfect for trapping ions.

The addition of microwave-transparent polymer also makes the material more permeable to electromagnetic waves.

"Remarkably, combining polyurethane, a common polymer used in common wall paint, with a tiny amount of MXene filler-about one part MXene in 50 parts polyurethane-can absorb more than 90% of incident electromagnetic waves covering the entire band of radar frequencies-known as X-band frequencies," said Meikang Han, a researcher at Drexel. "Radio waves just disappear inside the MXene-polymer composite film-of course, nothing disappears completely, the energy of the waves is transformed to a very small amount of heat which is easily dissipated by the material."

The significance of a material that can absorb X-band waves cannot be overstated.

Falling within the range of roughly eight to 11.2 gigahertz, X-band is established as the microwave radio region of the electromagnetic spectrum.

This means radars, radios, satellites, wireless networks, and cell phones.

The Institute of Electrical and Electronics Engineers, or IEEE, uses letters to signify a range of frequencies from one to 170 GHz. The X-band is most often used for radar applications as it has a short wavelength, meaning it can transmit more stably.

This band is used for civil, military, and government radar applications, including weather monitoring, air traffic control, maritime vessel traffic control, defense tracking, and even vehicle speed detection by law enforcement.

In addition to radar, the X-band is used for satellite and terrestrial communications. At the frequency range between 8.175 to 8.125 GHz, it is perfectly suited for meteorological satellites for monitoring weather conditions. This is because the X-band has extremely low rates of atmospheric attenuation, making it ideally suited for the harshest weather conditions and providing exceptionally high link availability for SATCOM and weather monitoring radar solutions.

With this picture painted, one can get a brief glimpse at how pervasive electromagnetic waves have permeated our way of life.

As technological advancements will only continue to saturate the "airways," devices that can absorb, instead of deflect signals, is a massive breakthrough in noise pollution, so to speak.

A thin coating of the vanadium-based MXene material-less than the width of a human hair-could render a material impermeable to any electromagnetic waves in the X-band spectrum, which includes microwave radiation.

Gogotsi predicts that this development could be important for high-stakes applications such as medical and military settings when maintaining technological performance is crucial.

"Our results show that vanadium-based MXenes could play a key role in the expansion of Internet of Things technology and 5G and 6G communications," Gogotsi added. "This study provides a new director for the development of thin, highly absorbent, MXene-based electromagnetic interference protection materials."