Spinning carbon nanotubes into gossamer wireless antennas

Researchers at the University of Cincinnati have spun tiny carbon nanotubes into fine but very strong threads that successfully send and receive radio signals. The basic technology to grow high quality carbon nanotubes to very long lengths was created by researchers Vesselin Shanov and Mark Schulz in the UC College of Engineering NanoWorld Lab, who then spun the fibers into threads. The university has more details including videos online. Colleague David Mast, an associate professor of physics at UC’s McMicken College of Arts and Sciences, took a 25-micron carbon nanotube thread and created a dipole antenna using double-sided transparent tape and silver paste. He was immediately successful in transmitting radio signals, and picking up AM and FM signals. “It transmitted almost as well as the copper did, but at about one ten-thousandth of the weight,” says Mast. Mast then dismantled his cell phone, pulled out the original antenna and replaced it with one he created from the same type of nanotube thread and tape. With the new antenna, he was able to get five “bars” of service, whereas there were none with the original antenna. His biggest challenge: “The hardest thing is to manipulate them. They float on ambient air,” he says. According to Schulz, the thread work well as an antenna because of the “skin effect.” “The electrons transfer well because they want to go to the surface,” he says. “Instead of traveling through a bulk mass, they are traveling across a skin.” They’re not the only ones studying how nanotechnology can benefit wireless. An IBM team, with a DARPA grant, is working on nano-based transceivers. The materials being used could lead to base station and mobile phone chips that are much more sensitive than today’s chips. Such chips would make more efficient use of radio signals and even be able to work in areas where today’s phones can’t.