published by Nanotechnology Now, 7thWave, Inc Copyright © 2005.
In November, Robotics Today published an invited
extended nanorobotics tutorial (23 pages) with many technical
details on aspects related to medical nanorobots development
(1). The work addressed questions about the feasibility
of nanorobotics, such as motion control, communication,
surrounding means interaction, and biocompatibility. It
described as well the many benefits nanorobots may provide
through the development of new biomedical treatments. We
decided to ask Adriano Cavalcanti his opinion about what
people may expect from nanorobotics.
The film Fantastic Voyage is quite often associated
with nanorobots being used to combat health problems.
Will advances in nanotechnology enable nanorobots?
Cavalcanti: Many times science fiction is in fact inspired by reality or based
on scientific discussions. For example, Jules Verne's From the Earth to
the Moon (1865) (2) described travel to the moon, and was inspired from
real developments in astrophysics from that period (3). In the year when that
book was written, travel could be thought of as impossible for many people.
However, now our society is planning to travel to Mars, and most recently has
sent autonomous robots to explore the red planet (4). Also during the 19th
century, many scientists thought that never would it be possible to determine
a star's chemical composition. However, in the 20th century, spectrometry using
quantum physics was successfully applied to determine their composition.
In 1966, Fantastic Voyage (5) was influenced and inspired partially
by real and polemic discussions emerging from statements by the physicist and
Nobel prize winner Richard P. Feynman. Feynman had announced the feasibility
of nanotechnology in 1959 (6), where the manufacturing of nanomachines could
be expected as a quite natural result of advances in technology. Indeed, the
speed of new developments is growing faster than ever for these technologies.
What steps must be achieved to build a nanorobot
for human medical use?
Cavalcanti: Manufacturing nanorobots requires advances in diamondoid rigid
materials (7). This technology has been demonstrated as feasible, and the manufacturing
of nanodevices has been growing in recent years (8). Diamondoid manufacturing
is moving step by step, and we are acquiring the requisite understanding to
be moving towards manufacturing robots in sizes comparable to bacteria.
For example, a few months ago the first mobile robot was build that measures
60 microns by 250 microns (9). At this scale you can begin to envision in the
coming years robot sizes decreasing rapidly to 100 microns, and then to 50
microns, and so forth.
An Intel prototype 90-nm process facility has already produced a fully functional
52 Mb SRAM with transistor gate lengths of 50 nm and SRAM cell sizes of just
1um 2 , or roughly half the cell size of today's most advanced SRAMs (10).
This downscaling will continue, according to the Semiconductor Industry Association's
roadmap. By 2016, high-performance ICs will contain more than 8.8 billion transistors
in a 280 mm 2 area - more than 25 times as many as on today's chips built with
130-nm feature sizes.
Inside the human body you have small vessels, 30-60 microns in diameter; therefore,
you can see it is quite natural to expect the first nanorobots in the next
10 years (11).
Nanotechnology for Medicine
At this time does there exist any human or animal
Cavalcanti: Indeed, there are many fully functional nanodevices built, such
as motors, sensors, biomolecular computing, and nanotransistors (12). At the
moment the main challenge is to integrate the several parts of distinct existing
nanodevices into a controllable nanorobot. To achieve that, there are several
research teams around the globe working in collaboration through interdisciplinary
projects, where the application of computational simulations are being used
to help as a valuable tool for testability and system integration. Overall,
assuring suitable control over such nanomachines is one of the challenging
issues to enable nanorobots, and actually you can evaluate it through computational
Using nanorobots in human beings will be done after several hundreds of tests
carried out in minimal details first with laboratory mice (13). Indeed, this
long testing investigation process is usually done for any new biomedical technology
in development. Actually, you have the successful use of nanoshells being tested
in mice for the fight against cancer (14). The use of nanoshells results from
the application of advances in nanotechnology, and is showing very positive
results as a kind of nanomedicine approach. With the progressive development
towards nanorobots, we may expect even more formidable benefits in health care.
What will be required from a nanorobot to operate
in a human body?
Cavalcanti: To be most effective, the ideal length of nanorobots should be
no larger than 3 microns in diameter. The nanorobot must have efficient transducers
and actuators, with low computational cost, and effectively be able to interact
with its surroundings once inside the human body. Therefore, the nanorobot
should contain an embedded integrated system required to effectively respond
in real time with this environment. Hence, the nanorobot behaviors are expected
to respond using motors for locomotion, when such motion control activation
becomes necessary due to some kind of biomedical intervention. Nanorobot sensor-based
control could be achieved through chemical or thermal nanosensors (15).
Can you foresee patients accepting nanorobots
for use inside their bodies?
Cavalcanti: Any medicament to be used in human beings must first be approved
after a long set of tests in the laboratory; it doesn't matter whether it is
a traditional medicament or a new nanotechnology-based approach for nanomedicine
(16). Once good results have been demonstrated with hundreds of laboratory
trials, and even more clinical tests, we may become naturally more confident
and comfortable with methods that may help relieve people's suffering. It is
natural to expect people to adopt proven biomedical technologies in their everyday
life, including nanoshells, DNA based nanomedicine, as well as nanorobots.
with permission from Adriano Cavalcanti ,
first published by
Copyright © 2005.