How Should Microrobots Swim?

Microrobots have the potential to dramatically change many aspects of medicine by navigating through bodily fluids to perform targeted The International Journal of Robotics Research Vol. 28, No. 11–12, November/December 2009, pp. 1434–1447 DOI: 10.1177/0278364909341658 c The Author(s), 2009. Reprints and permissions: http://www.sagepub.co.uk/journalsPermissions.nav Figures 1, 3, 5–10 appear in color online: http://ijr.sagepub.com diagnosis and therapy. Researchers have proposed numerous microrobotic swimming methods, with the vast majority utilizing magnetic fields to wirelessly power and control the microrobot. In this paper, we compare three promising methods of microrobot swimming (using magnetic fields to rotate helical propellers that mimic bacterial flagella, using magnetic fields to oscillate a magnetic head with a rigidly attached elastic tail, and pulling directly with magnetic field gradients) considering practical hardware limitations in the generation of magnetic fields. We find that helical propellers and elastic tails have very comparable performance, and they generally become more