For better antennas, add this ‘smart’ material

"A good example is the military," Nelson Sepulveda says of cell and radio antennas. "If you're communicating on one channel and suddenly the enemy jams it, you need to switch because it's become compromised. Now that is very easy to do." (Credit: US Army Public Affairs Midwest/Flickr)

Scientists are manipulating a material known as vanadium dioxide, or VO2, and making it useable at a size barely visible to the naked eye.

“My research team works on integrating smart materials in small devices and systems,” says Nelson Sepulveda, an associate professor of electrical and computer engineering at Michigan State University, who is leading the work.

“Think about shrinking a robot and making it fit inside a human hair.”

More recently, researchers extended the applications of VOby integrating the material in antennas, which makes tuning them easier.

The material experiences what’s known as a solid-to-solid phase change, which means it remains a solid (instead of becoming a liquid or gas). In other words, the material is a solid at room temperature, but when you heat it up slightly, it becomes another type of solid with very different properties.

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This ability to alter its shape is particularly useful in the communications field. Specifically, it can be used in radio and cell phone antennas, allowing a user to switch bands using the same antenna.

“A good example is the military,” Sepulveda says. “If you’re communicating on one channel and suddenly the enemy jams it, you need to switch because it’s become compromised. Now that is very easy to do.”

Another practical use for this smarter smart material is in the field of health and medicine.

“When perfected, it could allow for very precise microsurgery, helping surgeons pinpoint tissue for selective treatment,” Sepulveda says.

[Tunable antenna could end annoying dropped calls]

The advantage of VO2 is it is able to change phases very easily and in a reversible way. Often phase changes in other materials involve extreme temperature changes, and in many cases the phase change is not reversible. Additionally, the material remembers what is happening to it—that is, the material has memory.

“That’s the beauty of it,” Sepulveda says. “It’s the only smart material that has a phase change that is relatively close to room temperature.”

Researchers from the South Dakota School of Mines and Technology contributed to the work, which the National Science Foundation funds.

The research appeared earlier this year in the IEEE Antennas and Wireless Propagation Letters.

Source: Michigan State University