One of the most prominent impediments to technological advancements of next-generation devices (things like form factor and weight) is inflexibility. Until recently, circuit substrates and hardware were rigid, for the most part (we are not talking about
interconnect cables here). The inflexibility issue plagues wearables, smart clothing, medical implants, and, soon, Internet of Everything/Everyone (IoX) devices.
While there have been orders of magnitudes of advances in miniaturization, flexibility is a frontier hard to conquer. However, of late, we are beginning to see advancements in flexible fabrics that are bringing the elusive flexibility to, formerly rigid, circuit boards. Components, not so much – yet.
However, miniaturization can only go so far. Eventually flexible circuits will have to come into play to step over the horizon and develop the next wave of devices for a number of different segments and applications. While we still have a bit of a journey in this segment before we have truly “fabric” flexibility circuit boards, various segments are developing radical new technologies.
One of the hardest devices to make flexible are antennas. While we have, virtually, unlimited configuration options for today’s antennas, one of them is not flexibility. Therefore, developments in flexible antennas are exciting.
To that end, researchers at the Drexel University Materials Science and Engineering Department have been working with nanomaterials to find new solutions to traditionally sticky problems, such as antenna configuration and design. Back in 2011, these researchers found a way to combine various metals (titanium, molybdenum, vanadium, and niobium), with carbon or nitrogen atoms, to create a material that is only a few atoms thick, very strong, and has excellent conductivity. They named them MXenes (pronounced “maksens”),
Fast forward to 2018 and the research has produced an interesting application – spray-on antennas. Mixing these MXenes with water opens a new world of applications for antennas. Essentially, the compound can be sprayed on virtually any surface, including walls and windows (that opens a completely new world for 5G wireless) 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.
The applications are unlimited. Hospital gowns that monitor a slew of patient conditions. Smart clothing that can interface with smart cities. Vehicles with antennas integrated into the paint, credit cards and passports, access and tracking applications, and applications that we have not even visualized, yet. As well, the applications for security are widespread and IoX devices can have unlimited form factors. Moreover, all of this is barely scratching the surface.
Research has been going on hot and heavy. Early successes include energy storage devices, electromagnetic interference shielding, water filtration, chemical sensing, structural reinforcement, cancer treatment, gas separation, and more, with and without RF interfaces and flexible antennas.
As it turns out, MXenes conductivity is an excellent transmitter of radio waves. And it can be made directional. Imagine the implication for this in X by X MIMO applications. Initial tests indicate it can perform as well as typical antenna materials such as gold, silver, copper or aluminum. And because of its size and flexibility, they find applicability in areas where space prevents traditional antenna installations, or the form factor is not conducive to antenna application.
The way antennas are formed using MXenes is to create a compound from two-dimensional titanium carbide and water. This forms an evaporative ink that, once the water evaporates, leaves behind an electronically conductive, chemically stable and strong material. This can be sprayed, or printed using inkjet technologies, onto just about any surface. After the water evaporates, the result is dried layers of MXene.
Other tests have shown that varying the thickness of the MXenes varies its conductive and radiating properties. Slightly thicker MXene antennas, about one-tenth the thickness of a piece of paper, have been shown to outperform antennas made of other high-tech nanomaterial-based antennas such as carbon nanotubes, graphene, and nano-silver inks.
Finally, in addition to what already seems to be too good to be true, MXene antennas are easier and cheaper to produce. Typically, other nanomaterials fabrication processes require mixing the electronically capable ingredients with other materials to help them stick to each other. Then the compound must be heated to strengthen their interconnections. MXene antennas are made by simply mixing MXenes with water and then spraying them on with any spraying device.
This is one of the more exciting developments in technology. As I discussed earlier, having cheap, flexible, form factor-less antennas opens unlimited possibilities for wireless applications. This evolutionary development opens a new frontier for electronic devices of any size and shape that can be anywhere and still communicate effectively.