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

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

6.1 Nanodevice Energy Resources

Device energetics may represent the most serious limitation in nanorobot design. Almost all medical nanodevices will be actively powered. Mechanical motions, pumping, chemical transformations and the like all require the expenditure of energy, measured in joules. Even a drug molecule interaction with a biological receptor site reduces free energy by ~50 kT (Section 3.5.2) or ~210 zJ (1 zeptojoule (zJ) = 10^-21 joule) at 310 K. Heat dissipation is also a major consideration in nanomachine design, particularly when large numbers of nanomachines are deployed. Power, of course, is the rate of energy consumption or production, measured in joules/sec or watts.

Energy, like money, has both a storage and a transactional character. Section 6.2 reviews the various forms of stored energy that may be accessible to working nanodevices in vivo. Section 6.3 describes how one form of energy can be converted into another form, while Section 6.4 discusses how energy may be transmitted from one place to another -- both representing the transactional aspect of energy use. Section 6.5 closes the Chapter with an enumeration of issues and techniques useful in assessing energy requirements and performance restrictions in medical nanodevice design.

Last updated on 18 February 2003