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

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

5.3.1.2 Keyhole Passage

The minimum aperture through which a longitudinally stretched but laterally compressed nanodevice may pass is determined mainly by the minimum size of its internal incompressible components, not the minimum turning radius of its skin. The smallest working complex nanomachines of the human body, the ribosomes, are ~25 nm in diameter; the minimum size of a ~100 pW mechanochemical power supply is ~50 nm (Section 6.5.3). Add to this the width of the integument component blocks and it is difficult to imagine even the most flexible artificial nanodevice squeezing through a keyhole less than 50 nm in diameter -- roughly the maximum dimension of the intercellular contact space.⁵²⁶ A design limit of 100 nm would be more conservative.

In the macroscopic world, the octopus can stretch itself quite thin, passing rubberlike through small holes and narrow crevasses less than 10% of its size; arms, eyes, and even head can alter shape and elongate when necessary, with keyhole passage limited by its beak, the only hard part in its body.³¹³³

Last updated on 17 February 2003