Nanorobotics is an emerging technology field creating machines or robots whose components are
at or near the scale of a nanometre(10−9 meters).[1][2][3] More specifically, nanorobotics (as opposed
to microrobotics) refers to the nanotechnology engineering discipline of designing and
building nanorobots, with devices ranging in size from 0.1–10 micrometres and constructed
of nanoscale or molecularcomponents.[4][5] The terms nanobot, nanoid, nanite, nanomachine,
or nanomite have also been used to describe such devices currently under research and
development.[6][7]
Nanomachines are largely in the research and development phase,[8] but some primitive molecular
machines and nanomotors have been tested. An example is a sensor having a switch approximately
1.5 nanometers across, able to count specific molecules in a chemical sample. The first useful
applications of nanomachines may be in nanomedicine. For example,[9] biological machines could be
used to identify and destroy cancer cells.[10][11] Another potential application is the detection of toxic
chemicals, and the measurement of their concentrations, in the environment. Rice University has
demonstrated a single-molecule car developed by a chemical process and
including Buckminsterfullerenes (buckyballs) for wheels. It is actuated by controlling the
environmental temperature and by positioning a scanning tunneling microscope tip.
A ribosome is a biological machine.
Another definition is a robot that allows precise interactions with nanoscale objects, or can
manipulate with nanoscale resolution. Such devices are more related to microscopy or scanning
probe microscopy, instead of the description of nanorobots as molecular machine. Using the
microscopy definition, even a large apparatus such as an atomic force microscope can be
considered a nanorobotic instrument when configured to perform nanomanipulation. For this
viewpoint, macroscale robots or microrobots that can move with nanoscale precision can also be
considered nanorobots.
Nanorobotics theory[edit]
According to Richard Feynman, it was his former graduate student and collaborator Albert
Hibbs who originally suggested to him (circa 1959) the idea of a medical use for Feynman's
theoretical micromachines (see nanomachine). Hibbs suggested that certain repair machines might
one day be reduced in size to the point that it would, in theory, be possible to (as Feynman put it)
"swallow the surgeon". The idea was incorporated into Feynman's 1959 essay There's Plenty of
Room at the Bottom.[12]
Since nanorobots would be microscopic in size, it would probably be necessary for very large
numbers of them to work together to perform microscopic and macroscopic tasks. These nanorobot
swarms, both those unable to replicate (as in utility fog) and those able to replicate unconstrainedly
in the natural environment (as in grey goo and its less common variants, such as synthetic
biology or utility fog), are found in many science fiction stories, such as the Borg nanoprobes in Star
Trek and The Outer Limits episode "The New Breed".
Some proponents of nanorobotics, in reaction to the grey goo scenarios that they earlier helped to
propagate, hold the view that nanorobots able to replicate outside of a restricted factory environment
do not form a necessary part of a purported productive nanotechnology, and that the process of self-
replication, were it ever to be developed, could be made inherently safe. They further assert that
their current plans for developing and using molecular manufacturing do not in fact include free-
foraging replicators.[13][14]
The most detailed theoretical discussion of nanorobotics, including specific design issues such as
sensing, power communication, navigation, manipulation, locomotion, and onboard computation, has
been presented in the medical context of nanomedicine by Robert Freitas.[15][16] Some of these
discussions remain at the level of unbuildable generality and do not approach the level of detailed
engineering.
Legal and ethical implications[edit]
Open technology[edit]
A document with a proposal on nanobiotech development using open design technology methods,
as in open-source hardware and open-source software, has been addressed to the United Nations
General Assembly.[17] According to the document sent to the United Nations, in the same way
that open source has in recent years accelerated the development of computer systems, a similar
approach should benefit the society at large and accelerate nanorobotics development. The use
of nanobiotechnology should be established as a human heritage for the coming generations, and
developed as an open technology based on ethical practices for peaceful purposes. Open
technology is stated as a fundamental key for such an aim.
Nanorobot race[edit]
In the same ways that technology research and development drove the space race and nuclear
arms race, a race for nanorobots is occurring.[18][19][20][21][22] There is plenty of ground allowing
nanorobots to be included among the emerging technologies.[23] Some of the reasons are that large
corporations, such as General Electric, Hewlett-Packard, Synopsys, Northrop
Grumman and Siemens have been recently working in the development and research of
nanorobots;[24][25][26][27][28] surgeons are getting involved and starting to propose ways to apply
nanorobots for common medical procedures;[29] universities and research institutes were granted
funds by government agencies exceeding $2 billion towards research developing nanodevices for
medicine;[30][31] bankers are also strategically investing with the intent to acquire beforehand rights
and royalties on future nanorobots commercialisation.[32] Some aspects of nanorobot litigation and
related issues linked to monopoly have already arisen.[33][34][35] A large number of patents has been
granted recently on nanorobots, done mostly for patent agents, companies specialized solely on
building patent portfolios, and lawyers. After a long series of patents and eventually litigations, see
for example the Invention of Radio, or the War of Currents, emerging fields of technology tend to
become a monopoly, which normally is dominated by large corporations.[36]
Manufacturing approaches[edit]
Manufacturing nanomachines assembled from molecular components is a very challenging task.
Because of the level of difficulty, many engineers and scientists continue working cooperatively
across multidisciplinary approaches to achieve breakthroughs in this new area of development.
Thus, it is quite understandable the importance of the following distinct techniques currently applied
towards manufacturing nanorobots:
Biochip[edit]
Main article: Biochip
The joint use of nanoelectronics, photolithography, and new biomaterials provides a possible
approach to manufacturing nanorobots for common medical uses, such as surgical instrumentation,
diagnosis, and drug delivery.[37][38][39] This method for manufacturing on nanotechnology scale is in use
in the electronics industry since 2008.[40] So, practical nanorobots should be integrated as
nanoelectronics devices, which will allow tele-operation and advanced capabilities for medical
instrumentation.[41][42]
Nubots[edit]
Main article: DNA machine
A nucleic acid robot (nubot) is an organic molecular machine at the nanoscale.[43] DNA structure can
provide means to assemble 2D and 3D nanomechanical devices. DNA based machines can be
activated using small molecules, proteins and other molecules of DNA.[44][45][46] Biological circuit gates
based on DNA materials have been engineered as molecular machines to allow in-vitro drug delivery
for targeted health problems.[47] Such material based systems would work most closely to smart
biomaterial drug system delivery,[48] while not allowing precise in vivo teleoperation of such
engineered prototypes.
Surface-bound systems[edit]
Several reports have demonstrated the attachment of synthetic molecular motors to
surfaces.[49][50] These primitive nanomachines have been shown to undergo machine-like motions
when confined to the surface of a macroscopic material. The surface anchored motors could
potentially be used to move and position nanoscale materials on a surface in the manner of a
conveyor belt.
Positional nanoassembly[edit]
Nanofactory Collaboration,[51] founded by Robert Freitas and Ralph Merkle in 2000 and involving 23
researchers from 10 organizations and 4 countries, focuses on developing a practical research
agenda[52] specifically aimed at developing positionally-controlled diamond mechanosynthesis and
a diamondoid nanofactory that would have the capability of building diamondoid medical nanorobots.
Biohybrids[edit]
The emerging field of bio-hybrid systems combines biological and synthetic structural elements for
biomedical or robotic applications. The constituting elements of bio-nanoelectromechanical systems
(BioNEMS) are of nanoscale size, for example DNA, proteins or nanostructured mechanical parts.
Thiol-ene ebeam resist allow the direct writing of nanoscale features, followed by the
functionalization of the natively reactive resist surface with biomolecules.[53] Other approaches use a
biodegradable material attached to magnetic particles that allow them to be guided around the
body.[54]
Bacteria-based[edit]
This approach proposes the use of biological microorganisms, like the bacterium Escherichia
coli[55] and Salmonella typhimurium.[56] Thus the model uses a flagellum for propulsion purposes.
Electromagnetic fields normally control the motion of this kind of biological integrated
device.[57] Chemists at the University of Nebraska have created a humidity gauge by fusing a
bacterium to a silicone computer chip.[58]
Virus-based[edit]
Retroviruses can be retrained to attach to cells and replace DNA. They go through a process
called reverse transcription to deliver genetic packaging in a vector.[59] Usually, these devices are Pol
– Gag genes of the virus for the Capsid and Delivery system. This process is called retroviral gene
therapy, having the ability to re-engineer cellular DNA by usage of viral vectors.[60] This approach has
appeared in the form of retroviral, adenoviral, and lentiviral gene delivery systems.[61] These gene
therapy vectors have been used in cats to send genes into the genetically modified
organism (GMO), causing it to display the trait. [62]
3D printing[edit]
Main article: 3D printing
3D printing is the process by which a three-dimensional structure is built through the various
processes of additive manufacturing. Nanoscale 3D printing involves many of the same process,
incorporated at a much smaller scale. To print a structure in the 5-400 µm scale, the precision of the
3D printing machine is improved greatly. A two-steps process of 3D printing, using a 3D printing and
laser etched plates method was incorporated as an improvement technique.[63] To be more precise at
a nanoscale, the 3D printing process uses a laser etching machine, which etches into each plate the
details needed for the segment of nanorobot. The plate is then transferred to the 3D printer, which
fills the etched regions with the desired nanoparticle. The 3D printing process is repeated until the
nanorobot is built from the bottom up. This 3D printing process has many benefits. First, it increases
the overall accuracy of the printing process.[citation needed] Second, it has the potential to create functional
segments of a nanorobot.[63] The 3D printer uses a liquid resin, which is hardened at precisely the
correct spots by a focused laser beam. The focal point of the laser beam is guided through the resin
by movable mirrors and leaves behind a hardened line of solid polymer, just a few hundred
nanometers wide. This fine resolution enables the creation of intricately structured sculptures as tiny
as a grain of sand. This process takes place by using photoactive resins, which are hardened by the
laser at an extremely small scale to create the structure. This process is quick by nanoscale 3D
printing standards. Ultra-small features can be made with the 3D micro-fabrication technique used in
multiphoton photopolymerisation. This approach uses a focused laser to trace the desired 3D object
into a block of gel. Due to the nonlinear nature of photo excitation, the gel is cured to a solid only in
the places where the laser was focused while the remaining gel is then washed away. Feature sizes
of under 100 nm are easily produced, as well as complex structures with moving and interlocked
parts.[64]
Potential uses[edit]
Nanomedicine[edit]
Main article: Nanomedicine
Potential uses for nanorobotics in medicine include early diagnosis and targeted drug-delivery
for cancer,[65][66][67] biomedical instrumentation,[68] surgery,[69][70]pharmacokinetics,[10] monitoring
of diabetes,[71][72][73] and health care.
In such plans, future medical nanotechnology is expected to employ nanorobots injected into the
patient to perform work at a cellular level. Such nanorobots intended for use in medicine should be
non-replicating, as replication would needlessly increase device complexity, reduce reliability, and
interfere with the medical mission.
Nanotechnology provides a wide range of new technologies for developing customized means to
optimize the delivery of pharmaceutical drugs. Today, harmful side effects of treatments such
as chemotherapy are commonly a result of drug delivery methods that don't pinpoint their intended
target cells accurately.[74] Researchers at Harvard and MIT, however, have been able to attach
special RNA strands, measuring nearly 10 nm in diameter, to nanoparticles, filling them with a
chemotherapy drug. These RNA strands are attracted to cancer cells. When the nanoparticle
encounters a cancer cell, it adheres to it, and releases the drug into the cancer cell.[75] This directed
method of drug delivery has great potential for treating cancer patients while avoiding negative
effects (commonly associated with improper drug delivery).[74][76] The first demonstration of
nanomotors operating in living organism was carried out in 2014 at University of California, San
Diego.[77] MRI-guided nanocapsules are one potential precursor to nanorobots.[78]
Another useful application of nanorobots is assisting in the repair of tissue cells alongside white
blood cells.[79] Recruiting inflammatory cells or white blood cells (which include neutrophil
granulocytes, lymphocytes, monocytes, and mast cells) to the affected area is the first response of
tissues to injury.[80] Because of their small size, nanorobots could attach themselves to the surface of
recruited white cells, to squeeze their way out through the walls of blood vessels and arrive at the
injury site, where they can assist in the tissue repair process. Certain substances could possibly be
used to accelerate the recovery.
The science behind this mechanism is quite complex. Passage of cells across the
blood endothelium, a process known as transmigration, is a mechanism involving engagement of
cell surface receptors to adhesion molecules, active force exertion and dilation of the vessel walls
and physical deformation of the migrating cells. By attaching themselves to
migrating inflammatory cells, the robots can in effect “hitch a ride” across the blood vessels,
bypassing the need for a complex transmigration mechanism of their own.[79]
As of 2016, in the United States, Food and Drug Administration (FDA) regulates nanotechnology on
the basis of size.[81]
Soutik Betal, during his doctoral research at the University of Texas, San Antonio developed
nanocomposite particles that are controlled remotely by an electromagnetic field.[82] This series of
nanorobots that are now enlisted in the Guinness World Record,[82] can be used to interact with
the biological cells.[83] Scientists suggest that this technology can be used for the treatment
of cancer.[84]
Cultural references[edit]
The Nanites are characters on the TV show Mystery Science Theater 3000. They're self-replicating,
bio-engineered organisms that work on the ship and reside in the SOL's computer systems. They
made their first appearance in season 8.
Nanites are used in a number of episodes in the Netflix series "Travelers". They are programmed
and injected into injured people to perform repairs.
