The cellulose films that Kim has made so far cannot exert much force – a must for robotics applications. So he’s working with Zoubeida Ounaies, assistant professor of aerospace engineering at Texas A&M University, to strengthen this “smart” cellulose. Ounaies adds carbon nanotubes, prized for their high electrical conductivity and strength, to dissolved cellulose. The mixture is still under study, but the idea is that films of cellulose strands intimately tangled with carbon nanotubes can exert more force than pure cellulose films.
Cellulose is cheap and readily available – Kim’s film can even be made by treating commercially available paper. By comparison, the most commonly used electrically active polymer, polyaniline, costs $68 per gram, says Victoria Finkenstadt, a research chemist at the USDA Agricultural Research Service. Although the robustness and strength of cellulose have yet to be demonstrated, it may also prove to be a good material for the artificial muscles used in robotics, says Finkenstadt.
“These materials may give us [robot] locomotion we’ve never dreamed of,” says Kwang J. Kim, associate professor of mechanical engineering at the University of Nevada in Reno (who was not involved with the cellulose research). But Kim says the field of electrically active polymers is still young, and researchers are still developing applications. “In a few more years interesting technologies will be coming out,” he predicts.