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Bio-Nanorobotics 203

The field of nanorobotics studies the design, manufacturing, programming, and control of the nano-
scale robots.
This review chapter focuses on the state of the art in the emerging field of nanorobotics and its
applications and discusses in brief some of the essential properties and dynamical laws which make
this field more challenging and unique than its macro-scale counterpart. This chapter is only
reviewing nano-scale robotic devices and does not include studies related to nano-precision tasks
with macro-robotic devices that usually are also included in the field of nanorobotics (e.g., Atomic
Force Microscope (AFM) and other forms of proximal probe microscopy).
Nanorobots would constitute any active structure (nano-scale) capable of actuation, sensing,
signaling, information processing, intelligence, and swarm behavior at nano-scale. These function-
alities could be illustrated individually or in combinations by a nanorobot (swarm intelligence and
cooperative behavior). So, there could be a whole genre of actuation and sensing or information
processing nanorobots having ability to interact and influence matter at the nano-scale. Some of the
characteristic abilities that are desirable for a nanorobot to function may include:

(i) swarm intelligence — decentralization and distributive intelligence;
(ii) self-assembly and replication — assemblage at nano-scale and ‘‘nano-maintenance’’;
(iii) nano-information processing and programmability — for programming and controlling nano-
robots (autonomous nanorobots);
(iv) nano- to macro-world interface architecture — an architecture enabling instant access to the
nanorobots and its control and maintenance.

There are many differences between macro- and nano-scale robots. However, they occur mainly in
the basic laws that govern their dynamics. Macro-scaled robots are essentially in the Newtonian
mechanics domain whereas the laws governing nanorobots are in the molecular quantum mechanics
domain. Furthermore, uncertainty plays a crucial role in nanorobotic systems. The fundamental
barrier for dealing with uncertainty at the nano-scale is imposed by the quantum and the statistical
mechanics and thermal excitations. For a certain nanosystem at some particular temperature, there
are positional uncertainties that cannot be modified or further reduced (Drexler, 1992).
The nanorobots are invisible to the naked eye, which makes them hard to manipulate and work
with. Techniques like scanning electron microscopy (SEM) and atomic force microscopy (AFM)
are being employed to establish a visual and haptic interface to enable us to sense the molecular
structure of these nano-scaled devices. Virtual reality (VR) techniques are currently being explored
in nano-science and biotechnology research as a way to enhance the operator’s perception (vision
and haptics) by approaching more or less a state of ‘‘full immersion’’ or ‘‘telepresence.’’ The
development of nanorobots or nanomachine components presents difficult fabrication and control
challenges. Such devices will operate in microenvironments whose physical properties differ from
those encountered by conventional parts. Since these nano-scale devices have not yet been
fabricated, evaluating possible designs and control algorithms requires using theoretical estimates
and virtual interfaces or environments. Such interfaces or simulations can operate at various levels
of detail to trade-off physical accuracy, computational cost, number of components, and the time
over which the simulation follows the nano-object behaviors. They can enable nano-scientists to
extend their eyes and hands into the nano-world, and they also enable new types of exploration and
whole new classes of experiments in the biological and physical sciences. VR simulations can also
be used to develop virtual assemblies of nano and bio-nano components into mobile linkages and to
predict their performance.
Nanorobots with completely artificial components have not been realized yet. The active area of
research in this field is focused more on molecular machines, which are thoroughly inspired by
nature’s way of doing things at nano-scale. Mother Nature has her own set of molecular machines
that have been working for millions of years, and have been optimized for performance and design
over the ages. As our knowledge and understanding of these numerous machines continues to