© 1999 Robert A. Freitas Jr. All Rights Reserved.

Robert A. Freitas Jr., Nanomedicine, Volume I: Basic Capabilities, Landes Bioscience, Georgetown, TX, 1999

9.4.2.5.4 Viscous Anchoring

By extending ahead of it a structure whose surface area is capable of being expanded, a nanorobot can set an anchor forward along its path, then winch itself towards the anchor. In a typical cycle, the deflated anchor is thrust forward. Then the anchor is expanded tenfold in area (thus increasing its viscous resistance to backwards movement by approximately tenfold). The nanorobot pulls itself forward by attempting to reel in the anchor. The anchor is then deflated, and the cycle is repeated. The anchor mechanism may resemble an umbrella that is opened and closed, or a balloon that is inflated and deflated, at the end of a telescoping rod. A second anchor placed aft and countercycled with the first permits continuous motion by alternating pushing with pulling; noncoaxial anchor settings allow arbitrary rotation and access to all headings in three-dimensional space.

Energy efficiency can be good because less fluid may be sheared during nanorobot movement, although in 1998 this method had not been widely studied. If the forward anchor is pushed many diameters ahead before inflation, then even the expansion of an anchor much larger than the nanorobot might prove less energy-expensive than anything except a device with skin than could flow backwards to match laminar streamlines (Section 5.1).

Last updated on 21 February 2003