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

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

9.4.4.4 Nanorobot Conjugation and Partition

Occasionally it may be necessary for two or more motile nanorobots to dock, or conjugate,^3617-3632 during histonatation (e.g., Section 8.3.3). Assuming the existence of in vivo communication and navigation networks (Sections 7.3 and 8.3), two nanorobots that are attempting to dock can exchange positional information until the two devices are within a range of ~3 microns. Once within such close range, the devices switch to ~GHz chirps which, from Eqn. 4.52, attenuate ~0.001%/nm in 310 K plasma. Using an acoustic receiver sensitive to 10^-6 atm pressure changes, and 0.01-atm transmitted pulses, and assuming that no other nanorobots are present and chirping in the immediate vicinity at the same time, the two nanorobots can locomote up the attenuation gradient to within ~10 nm proximity, approximately the minimum scale of the docking mechanism (e.g., metamorphic bumpers; Section 5.4). Conjugating microbes employ chemical communications to similar effect.^3628,3629

Once physical contact is made, nanomechanical communication at ~1 GHz transfers ~1000 bits during a ~1 microsec contact event (Section 7.2.4), sufficient to mutually validate identity. A universal clamp may be used for unrestricted docking among devices of any machine species that meet in any orientation. Device shape or surface features can be used to control docking orientation (Section 5.4.1). Docking clamps can also be designed to connect in only one way if the spatial or rotational positioning of the conjugated pair is an important mission requirement; from Eqn. 3.1, Brownian motion provides ~4000 random docking trials per second for two 1-micron nanorobots maintaining a mean 10-nm separation in 310 K interstitial fluid. Docking clamps may serve a purely adhesive function,^3630-3632 or may additionally provide communicating junctions that transfer fluids, power, or data between conjugated devices. Similar procedures permit three or more nanorobots to conjugate in vivo, and may allow a growing nanorobot aggregate to sequentially add new members to the collective at specific locations in the developing structure.

Partition,^3617-3619 or separation of linked nanorobots, requires a defined procedure in which all transtegumental openings in nanorobots are sealed or valved shut prior to release of docking clamps and physical separation. Once separated, and depending upon their mode of locomotion and the timing of their release, partitioned nanorobots must temporarily observe a dense-traffic protocol involving slower and lower-amplitude motions of motive appendages or rotating elements in order to:

1. avoid mechanical conflict among such appendages or elements between neighbors;

2. avoid potentially chaotic hydrodynamic interactions (Section 9.4.2.3); and

3. clear a sufficient interdevice distance to preclude significant error in positional readings from the navigation grid (Section 8.3.3), due to spurious acoustic refraction and attenuation effects if there is a large number density of nanorobots in the vicinity.

Last updated on 21 February 2003