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

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

7.2.6 Communicytes

A useful supplemental means of information transport throughout the body is a mobile mass-storage memory device called a communicyte. Communicytes may serve an analogous function to postal carriers -- messages are delivered to them, passed among them, and eventually delivered by them to the intended recipients. Mass mailings to selected recipient subpopulations are also possible. Classes of communicyte mass memory may include rapidly spooled hydrofluorocarbon memory tape (Section 7.2.1.1), dense banks of diamondoid register rods forming a random access memory (RAM) (Fig. 10.2), or other means (Section 10.2).

In the first case, a 1 micron³ storage block could contain a 10¹⁰ bit, 0.4-micron³, 3-meter length of memory tape, with the remaining 0.6-micron³ volume occupied by read/write heads, spool drivers, housing and the like. With a read speed¹⁰ of ~30 cm/sec (~10⁹ bits/sec) the entire data cache may be offloaded in ~10 sec. The energy cost to rewrite the tape is 1-1000 zJ/bit (Sections 6.5.6 (B) and 7.2.1.8), hence the entire tape may be erased and overwritten in 1-1000 sec assuming a 10 pW tape-handling power budget, giving a write speed of 10⁷-10¹⁰ bits/sec.

In the second case, register rods of cross-section ~1 nm² (described in Drexler¹⁰) require ~4 nm of length to accommodate a single input/output rod pair and can store at least ~1 bit/40 nm³. Thus a 0.4 micron³ block of tightly-packed register-rod RAM may hold 10⁷ bits, with the remaining 0.6 micron³ of the 1 micron³ storage block reserved for springs, latches, and other essential mechanisms (including address-decoding logic) to access the stored data, and housings. Read and write speeds are ~10¹⁰ bits/sec; full-cycle energy losses are ~5 zJ/bit assuming 1 bit/register,¹⁰ a ~50 pW power draw during the ~1 millisec required to read or write the entire onboard data cache.

Communicytes may also incorporate mechanisms allowing data transfers among themselves or between themselves and living or artificial entities (Section 7.4). Communicytes will normally be deployed as components of a communication network of such devices, as described in Section 7.3.2, although they may also serve as mobile data repositories or software libraries.

Last updated on 19 February 2003