Light, flexible carbon nanotube antennas with copper-like performance

In 2013, a group of researchers led by Rice University’s Matteo Pasquali manufactured multifunctional carbon nanotube fibers that combined the typical strength and thermal conductivity of carbon fibers while possessing electrical conductivity comparable to metals and flexibility of textiles. Now, the Rice researchers teamed up with researchers from the National Institute of Standards and Technology to produce light carbon nanotube fiber antennas that matched the efficiency of copper-based antennas at 2.4GHz. Unlike metals, the new antennas do not lose electrical conductivity when bent. The researchers report their findings in Applied Physical Letters.

Following the technique they pioneered in 2013, the researchers dissolved carbon nanotubes in chlorosulfonic acid to disperse the carbon nanotubes and remove undesired particles. The processed material was then extruded through a spinneret into an acetone (or water) coagulant, producing fibers without the acid. To measure the radiation efficiency of carbon nanotube antennas, the researchers developed what they call a “plug-n-play test fixture” using aluminum ground plane and panel connector, silver epoxy, and low permittivity foam blocks. The fixtures were used to ensure the consistency of measurements by restricting the movements of the antennas, which by construction are flexible.

The research group is the first to perform direct measurements of the radiation efficiency of carbon nanotube antennas. With verified efficiency and flexibility, the antennas “would find niche markets, such as satellites, aircrafts, and drones,” explains E. Amram Bengio, the lead author of the APL paper. Bengio points out that the current study found reduced efficiency at 1GHz and hopes to investigate further, citing, in particular, the skin effect as a possible cause.

Source: “High efficiency carbon nanotube thread antennas,” by E. Amram Bengio, Damir Senic, Lauren W. Taylor, Dmitri E. Tsentalovich, Peiyu Chen, Christopher L. Holloway, Aydin Babakhani, Christian J. Long, David R. Novotny, James C. Booth, Nathan D. Orloff, and Matteo Pasquali, Applied Physics Letters (2017). The article can be accessed at https://doi.org/10.1063/1.4991822 .