Nanotube Technology Out-Muscles the Competition

  • Published
  • By Maria Callier
  • Air Force of Scientific Research
ARLINGTON, Va. --  With primary financial support coming from AFRL, the University of Texas at Dallas is researching a new kind of artificial muscle--one composed of carbon nanotubes--for use in Air Force aerospace and space applications. For more than 20 years, a team of researchers led by Dr. Ray Baughman, director of the NanoTech Institute at UTD, has made artificial muscle technology its focal point. The current phase of the group's pioneering work in this area stems from an exploratory research program funded by AFRL. While the researchers have invented a number of artificial muscle types, including conducting polymer and fuel-powered varieties, it is their carbon-nanotube-based muscle synthesis that has the most powerful implications to emergent AF capabilities.

Whereas natural muscles can achieve about 20% contraction per second, artificial muscles can contract approximately 30,000% per second. The UTD team's nanoformed muscles, which are 30 times stronger than natural muscles, comprise very thin aerogel sheets of carbon nanotubes (with each tube 1/10,000th the diameter of a human hair). Nanomuscle activation occurs via injection of a small positive charge into these sheets, which repulses other positive charges therein. On a weight basis, the synthetic muscles are as strong as steel in one direction and as elastic as rubber in two other directions. Their inherent combination of strength and flexibility enables these nonelectrochemically based, carbon-nanotube-constructed muscles to operate at extreme temperatures, making them especially attractive for space applications. Further, the technology is receiving attention as a possible means for endowing soldiers with superhuman strength through the use of exoskeletons, which would be advantageous in battlefield emergencies. The artificial muscles may also find a niche in the actuation of aircraft "smart skins," which enable aircraft to morph their appearance in situations of danger. If researchers pursuing this particular possibility are able to employ the exceptionally elastic, lighter-than-air carbon nanotube sheets to affect the boundary layers of micro and larger air vehicles, they will ultimately have facilitated a new type of controllability and increased flight efficiency.

In addition to leveraging AFRL sponsorship for their research, Dr. Baughman and his UTD colleagues are utilizing funding support provided by the Office of Naval Research, the Strategic Partnership for Research in Nanotechnology, and the Robert A. Welch Foundation.