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CHAPTER 1
1.1 HISTORY OF NANOTECHNOLOGY For the first time in the history of Nobel Prizes, in 1959 Richard.P.Feynman of the Southern California was awarded the Noble Prize for his work in Nanotechnology. But people at that time were pessimistic about his theory of manipulating atoms. People often muddle up Nanotechnology with Science Fiction. It often comes as a surprise to learn that the Romans & Chinese were using nanoparticles thousands of years ago. Of course, people were not aware that they were using nanotechnology and as they had no control over particle size, or even any knowledge of the nano scale. The icons of this revolution are Scanning Tunneling Microscopes [STM] and Atomic Force Microscope [AFM] that are capable of creating pictures of individual atoms and moving them from place to place.
1.2 EVOLUTION 1. The word word Nano comes comes from from Greek Greek word ‘nanos’ ‘nanos’ meaning meaning dwarf. dwarf. The term term Nano Nano is the factor of one billionth. 2. Albert Albert Einstei Einstein n first first proved proved that each molecule molecule measure measuress about about a nanome nanometer ter (a billionth of meter) in diameter. 3. “Norio “Norio Taniguchi” Taniguchi” of Tokyo Tokyo Universi University ty proposed proposed the word word Nano. Nano. 4. In 1950 1950 an elec electr tric ical al engin enginee eerr “Art “Arthu hurr Von Von Hipp Hippel el”” firs firstt propo propose sed d the the word word molecular technology. 5. The Nano world world was was exposed exposed through through a lecture lecture delivered delivered in in 1959 by “Feynman” “Feynman” with the help of Nano technology and Nano scale engineering. He said that there is a possibility to implement very ve ry small motors. 6. In 1981 1981 memb member erss of IBM Inst Instit itut utee “Geo “Georg rgee Binn Binnin ing” g” and and “Henr “Henric ich h Rober Rober”” manufa manufactu ctured red scanni scanning ng tunnel tunneling ing micros microscope cope (STM) (STM).. There There is a fortun fortunee to observe very minute atoms. This is one of the developments of Nano technology.
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1.3 INTRODUCTION Imagine a technology so powerful that it will allow such feats as desktop manufacturing, cellular cellular repair, repair, artifici artificial al intelligenc intelligence, e, inexpensive inexpensive space travel, travel, clean and abundant abundant energy and environ environmen mental tal restor restorati ation; on; a techno technolog logy y so portab portable le that that every every one can reap reap its benefits; benefits; a technology so fundamental that it will radically change the economic and political systems; a technology so imminent that most of people will see its impact within the lifetimes. Such is the promise of nanotechnology. Albert Einstein first proved that each molecule measures about a nanometer (a billionth of a meter) in diameter. In 1959, 1959, it was Richard P. Feynman who predicted a technological world composed composed of self-repl self-replicati icating ng molecules molecules whose purpose purpose would be the production of nano-sized nano-sized object objects. s. Almost Almost a hundre hundred d years years after after Einste Einstein’ in’ss insigh insightt and 40 years years after Feynman’s initial proposition, the nanometer scale looms large on the research agenda. The semiconductor industry is edging closer to the world of nanotechnology where components are miniastured to the point of individual individual molecules and atoms. atoms. A push is well underway to invent devices devices that will manufacture manufacture anything at almost no cost, by treating atoms discretely, like computers treat bits of information. This would allow automatic construction of consumer goods without traditional labour, like a Xerox mach machin inee prod produc uces es unlim unlimit ited ed rety retypi ping ng the the orig origin inal al info inform rmat atio ion. n. Elec Electr troni onics cs is fuel fuelle led d by miniasturisation. Working smaller has led to the tools capable of manipulating individual atoms, just as the proteins in a potato manipulate the atoms of soil, water and air to make copies of themselves. The shotgun marriage of chemistry and engineering called nanotechnology is ushering in the era of self replicating machinery and self-assembling consumer goods made from cheap raw atoms.
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3
CHAPTER 2 2.1 Definition A technology is defined defined as nano technology only if it it involves all of the following: following: 1. Research
and and
technology
dev developm opment
at
the
atomi omic,
molecular
or
macromolecular levels, in the length scale of approximately 1-100 nanometer range. 2. Creating Creating and using using structures structures,, devices devices and systems systems that that have novel proper properties ties and functions because of their small and/or intermediate size. 3. Ability Ability to to control control or manipul manipulate ate on the atomic atomic scale. scale. OR ‘Nano-technology’ is the production technology to get the extra high accuracy and ultra fine dimensions, i.e., the preciseness and fineness on the order of 1 nm (nanometer), 10 –9 meter in length. The name of ‘Nanotechnology’ originates from this nanometer. In the processing of materials, the smallest bit size of stock removal, accretion or flow of mate materi rial alss is prob probabl ably y of one atom atom or one one mole molecu cule le name namely ly 0.1~ 0.1~0. 0.2 2 nm in leng length th.. Therfore, the expected limit size of fineness would be of the order of 1 nm. Accordingly, ‘Nano-technology’ mainly consists of the processing of separation, consolidation and deformation of materials by one atom or one molecule. Needless to say, the measurement and control. OR Nanotechnology can best be considered as a “catch-all” description of activities at the level of atoms and molecules that have applications in the real world. A nanometer is a billionth billionth of a meter, meter, that is, about 1/80,000 of the diameter diameter of a human hair, or 10 times the diameter of a hydrogen atom.
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4
2.2 .what is Nanotechnology?
Nanotechnology—how big or small?
If a definition of technology is "the application of science and scientific knowledge for industrial or commercial objectives," then in its most simplistic form, nanotechnology might be specifically defined as "the application of science and scientific knowledge, at the nanoscale, for industrial or commercial objectives." In order to understand the size of material/matter involved at the nanoscale level, one needs to trace down the units of measurement, commencing with an ant (at the milliscale) and ending at the very bottom, at the nanoscale. The nanoscale is far from the smallest unit of measurement—it is however the smallest scale at which matter can be manipulated. Figure 1 illustrates where the nanoscale fits in with relation to other scales.
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5
NANOTECHNOLOGY:: IS IT REAL? NANOTECHNOLOGY
For the uninitiated, Nanotechnology might seem somewhat cartoonish, simply because of the funny word “nano.” But, rest assured, nanotechnology is very real…and it’s definitely not a cartoon. Understanding nanotechnology and nanoscience means learning how to think small… very small. This paradigm is a 180-degree turnaround from a world that up until now was built on thinking big. In the battle of the telescope versus the microscope, the stars always win out over the atoms. Afterall, we can see the stars with our own eyes. It takes tremendous imagination to see what something might look like at the molecular level. Well, nanotechnology takes place at the atomic, molecular or macromolecular levels, in the length scale of approximately 1-100 nanometer range. A nanometer is one-billionth of a meter. Forget your average lab microscope. Molecules consist of one or more a toms. So, how big is an atom? To get us there, our imaginations can start with one cubic inch of air, which consists of an estimated 500 billion molecules.
2.3 The Objectives Of Nano technology technology •
PC's billions of times faster then today
•
Safe and affordable space travel
•
Virtual end to illness, aging, death
•
No more pollution and automatic cleanup of existing pollution
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6
•
End of famine and starvation
•
Superior education for every child on Earth
•
Reintroduction of many extinct plants and animals
•
Terraforming Earth and the Solar System
•
Get essentially every atom in the right place.
•
Make almost any structure consistent with the laws of physics that we can specify in molecular detail.
•
Have manufacturing costs not greatly exceeding the cost of the required raw materials and energy
WHY DO WE NEED THIS TECHNOLOGY?
•
To evaluate new ideas and new concepts filtering out the emotional bia biase sess and and conf confus usio ion n that that seem seemss to inev inevit itabl ably y surr surroun ound d our our
perceptions of them. •
Production of smaller, less expensive highly integrated components in less time.
•
Better and faster technology.
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CHAPTER 3 3.1 Nano scale building blocks
Atoms If an atom were of the size of a small marble, a fairly complex molecule would be of the size of your fist. This makes a useful mental image, but atoms are really about 1/10,000 the size of bacteria, and bacteria are about 1/10,000 the size of mosquitoes. An atomic nucleus however is about 1/10,000 the size of the atom itself. All machines use clumps of atoms as parts. These atoms will bond together and form molecules. These molecules will be assembled like the components of an erector set; and well-bounded parts will stay put. Just as ordinary tools can build ordinary machines from parts, so molecular tools will bond molecules together to make tiny gears, motors, levers, and castings and assemble them to make complex machines.
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8 Nano structure is a particle of nanometer size. This designation has various meanings like cluster, big molecule, nano crystal embedded in a matrix etc. Nano Nano mete meterr scal scalee stru struct ctur ures es are are topo topolo logi gical cally ly clos closed ed and and holl hollow ow.. They They typi typica call lly y form form tabu tabula larr or spherical
morp orpholo ologies.
espe especi cial ally ly the the
It
is
case case for for carb carbon on,,
which presents a renewable diversity of structure on the nanometer scale. E.g.: Graphite Graphite and hexagonal boron boron nitrite nitrite (H-BN)
(The nearest nearest neighbor distance distancess
(0.144&0.142 nm), the inter layer spacing (C/2=0.33&0.335 nm)) are almost identical.
Nano Tubes: Tabul Tabular ar form formss of carb carbon, on, comm common only ly call called ed “Nano “Nano tube tubes” s”,, are are known known since since the the development of high resolution TEM. For instance, there were already described by A.Oberlin & M.Endo as early as 1976. Tubes are cylinders of concentric hexagonal layers (one to several tens of layers), with diameter in the order of the nanometer. nanometer. Tube lengths are macroscopic, so that the aspect ratio (length/diameter) can be up to 105. For energy considerations, tubes are believed to be several concentric layers rather than one of spiraling layer. Boundary limits after one rotation around the axis constraint a limited number of choices for the helicity of the hexagonal layer relatively to tube axis. Indeed there must be a continuity of hexagons on the cylinder. This limits the number of possible choices for helicity. Any vector joining two equivalent atoms in a grapheme plane can form the circumference
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9 of a tube. (Of course, this only has a physical meaning. If the diameter of the tube is neither too small nor too big) then the axis of the tube is defined perpendicular to this vector. Each vector in the graphene plane defines one helicity of the tube around its axis. There are two specific cases of helicity. 1. When the vector vector is perpendicula perpendicularr to the border border of one hexagon hexagon (Arm (Arm chair type). type). 2. When the the vector vector crosses crosses two atoms atoms opposed opposed in in the hexagon hexagon (‘Zigzag’ (‘Zigzag’ type). type). The nanotubes are of two kinds. 1. Mult Multiw iwal alll Nano Nanotu tube bess 2. Singl Singlee wall walled ed Nan Nanot otub ubes es
Nano layers /Onions (typically 10 to 300 nm): “Onions” are particles roughly rounded, constituted of atomic layers piled as onion. Morphologies are various. Often an onion is closed by facets and angles, rather than by a continuous curvature, forming a nano-polyhedron. Onions are often irregular and full of defects. This is because such such stru struct ctur uree diff diffic icul ultl tly y acco accomm mmoda odate tess the the inte interr laye layer r constraints in case of spherical curvatures. Onions probably feat featur uree diso disord rder er pili piling ng of laye layers rs (tur (turbo bost stra rati tic) c).. High Highly ly disordered onions are known to exist in common carbon soot. The The carb carbon on full fuller eren enee fami family ly is a grou group p of mole molecu cule les, s, with with chemi chemica call form formul ulaa C2n, (20
Quantum Dots: As the name implies, are tiny crystals composed of periodic groups of II-IV, III-V, are IV-VI materials that range in size from 2 to 10 nanometers or roughly the size of 10 to 50
9
10 atoms in diameter. Due to the extremely small size of the nano-particles, the optical, electronic, and chemical properties of the quantum dots are dominated by physical size and the chemistry of their surface. These are called QUANTUM CONFINEMENT effects. This quantum confinement results in a controlled blu bluee shif shifti ting ng of the the bulk bulk ener energy gy band band gap gap so that that pro proper perties
such
as
abso bsorption
onset
and
peak
photolumine photoluminescence scence wavelength are size dependent. In quantum dots strong strong absorption absorption occurs at specific photon energies, at the expense of reduced absorption at other energies. The quantum confinement can effectively enhance many non-linear effects due to a concentration of the oscillator strength into narrow wavelength bands. These include nonlinear nonlinear refractiv refractivee index, nonlinear absorption, absorption, Stark effect, effect, Electro-mag Electro-magneto neto optic effects. Colloid ally prepared nanocrystal quantum dots are free floating and can be coupled to a variet variety y of molecu molecules les via metal metal coordi coordinat nating ing functi functiona onall groups groups.. This This abilit ability y greatl greatly y increases the flexibility and application in which quantum dots can be used.
Phase II: All the above said Nano particles when assembled together forms nano structures. For all our advances in arranging atoms, we still use primitive methods. But today there is molecular technology MACHINE” by which we can assemble the molecules into nano structures.
Assemblers:
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11 Thes Thesee are are nano nano mach machin ines es,, whic which h will will serv servee as impr improv oved ed devic devices es for for asse assemb mbli ling ng molecular structures. The machine, which can be able to bond atoms together in virtually any stable pattern, according a few at a time to the surface of a work piece until a complex structure is complete is called an “ASSEMBLER”. They will let us build almost anything that the laws of nature allow to exist. There are two well-known architectural designs for assemblers. 1. Von Neumann’s Neumann’s architectur architecturee (Two-dimen (Two-dimensiona sionall 2D). 2. Drexler’s Drexler’s architectur architecture. e.
(Three-dim (Three-dimension ensional al 3D)
The Von Neumann architecture for a general manufacturing manufacturing system: Von Neumann‘s proposal consisted of two central elements: a universal computer and a universal constructer (see fig 1). The universal computer contains a program that directs the behavior of the universal constructor. The universal constructer, in turn, is used to manufacture both another universal computer and another universal constructor. Once construction is finished the program contained in the original universal computer is copied to the new universal computer and program execution is started.
UNIVERSAL COMPUTER
UNIVERSAL CONSTRUCTOR
The Von Neumann architecture for a self-replicating system.
Von Neumann worked out the details for a constructor that worked in a theoretical two dimensional cellular automata world. An important point to notice is that self-replication, while important, is not by itself an objective. A device able to make copies of itself but unable to make anything else would not be very valuable. Von Neumann’s proposals centered around the combination of a universal constructor, which could make anything it was directed to make, and a
11
12 universal computer, which could compute anything it was directed to compute. It is this ability to make anyone of a broad range of structures under flexible programmatic control that is of value. The ability of the device to make copies of itself is simply a means to achieve low cost, rather than an end in itself.
Drexler’s architecture for an assembler: assembler: Drexler’s assembler follows the Von Neumann kinetic architecture, but is specialized for dealing with systems made of atoms. The essential components in Drexler’s assembler are shown in fig 2.The emphasis here (in contrast to Von Neumann’s proposal) is on small size. The computer and constructor both shrink to the molecular scale, while the constructer takes on additional detail consistent with the desire to manipulate molecular structures with atomic precision. The molecular constructor has two major sub systems: 1. A posit positio iona nall capab capabil ilit ity y and 2. The The tip tip chem chemis istr try. y. The Drexler’s architecture for an Assembler is shown in the figure:
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Molecular Computer
Molecular Constructor
Molecular Positional Capability
Tip Chemistry
The positional capability might be provided by one or more small robotic arms, or alternatively might be provided by anyone of a wide range of devices that provide positional positional control. control. The emphasis, emphasis, though, is on a positional positional device that is very small in scale: perhaps 0.1 microns (100 nanometers) nan ometers) or so in size. The tip chemistry is logically similar to the ability of the Von Neumann universal constructor constructor to alter the state of a cell at the tip of the arm, but now the change in “state” “state” corresponds to a change in molecular structure. That is, we must specify a set of welldefined chemical reactions that take place at the tip of the arm, and the set must be sufficient to allow the synthesis of the structures of interest. It is worth nothing that current methods in computational chemistry are sufficient to model the kinds of structures that will appear in a broad class of molecular machines, including all of the structures and reactions needed n eeded for some assemblers
There are two concepts commonly associated with Nanotechnology: 1)POSITIONAL ASSEMBLY
2)SELF REPLICATION
POSITIONAL ASSEMBLY:
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14 This This posi positi tion onal al asse assemb mbly ly aims aims to plac placee the the righ rightt mole molecul cular ar part partss in the the right right pla place ce.T .The he need need for for posi positi tion onal al asse assemb mbly ly impl implie iess an inte intere rest st in mole molecu cula lar r roboti robotics. cs.e.g e.g.,r .,robot obotic ic device devicess that that are molecul molecular ar both both in their their size size and precis precision ion.. These molecular scale positional devices are likely to resemble very small versions of their everyday macroscopic counterparts.Positional assembly is frequently used in norm ormal
macr acroscopic
manufa ufacturing
today day,and
provides
treme emendou dous
advantages.Imagine trying to build a bicycle with both hands tied behind your back! The idea of manipulating and positioning individual atoms and molecules is still new and take takess some some gett gettin ing g used used to.h to.how oweve everr as Feyn Feynma man n said said “The “The prin princi cipl ples es of physics,do not against the possibility of maneuvering things atom by atom.” We need need to appl apply y at the the mole molecul cular ar scal scalee the the conce concept pt that that was was demo demons nstr trat ated ed it’s it’s effectivene effectiveness ss at the macroscoping macroscoping scale:making scale:making parts go where we want by putting them where we want! SELF REPLICATION: The remarkably low manufacturing cost comes from self replication.Molecular machines machines can make more molecular molecular machines,which machines,which can make yet more molecular molecular machines.While the research and development costs for such systems are likely to be quite high,incremental manufacturing costs of a system able to make systems like itself can be very low. Self replication is at the heart of many policy discussions.The only self replicating systems most of us are familiar with are biological. We automatically assume that nanotechnologi nanotechnological cal selfrepli selfreplicatin cating g systems systems will be similar. similar. The machines machines people
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15 make bear little resemblance to living systems and molecular manufacturing systems are likely to be just as dissimilar. The The arti artifi fici cial al self self repl replic icat atin ing g syst system emss are are bein being g prop propos osed ed for for mole molecu cula lar r manufacturing are inflexible and brittle.It is difficult enough to design a system able to self self repli replicat catee in a control controlled led enviro environme nment, nt,let let alone alone design designing ing one that that can approach the marvelous adaptibility that hundred’s of millions of years of evolution have given to living systems.Designing a system that uses a single source of energy is both much easier to do and produce a much more efficient system.Artificial self replicating systems will be both simpler and more efficient if most of this burden is offloaded:we can give them the odd compounds and unnatural molecular structures that they require in an artificial feedstock rather than forcing the device to make everything itself-a process that is both less efficient and more complex to design. The mechanical designs proposed for Nanotechnology are more reminiscent of a factory than of a living system.Molecular scale robotic arms able to move and positi position on molecul molecular ar parts parts would would assemb assemble le rather rather rigid rigid molecu molecular lar product productss using using methods more familiar to a machine shop than the complex brew of chemicals found in a cell.Although we are inspired by living systems,the actual designs are likely to owe more to design constraints and human h uman objectives than to living systems. Selfreplication is but one of many abilities that living systems exbhit. Copying that one ability in an artificial system will be challenge enough without attempting to emulate their many other remarkable abilities.The engineering effort required to design systems of such complexity will be significant,but shouldnot be greater than
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16 the
complexity
involv olved
in
the
design
of
such
exi existing
systems
as
computers,airplanes etc. THE VON NEUMANN ARCHITECTURE FOR FOR A SELF REPLICATING REPLICATING SYSTEM
UNIVERSAL
COMPUTER
UNIVERSAL
CONSTRUCTOR
Fig.vonneumann architecture of a self replicatingsystem Vonneumann’s proposal consisted of two central elements:a universal computer and a universal constructer see in above figure. The universal computer contains a program that directs the behavior of the universal constructor. constructor.The The universal universal constructo constructorr inturn,is inturn,is used to manufacture manufacture both another another universal computer and another universal constructor. Once Construction is finished the progra program m contai contained ned in the original original univer universal sal computer computer is copied copied to the new universal computer and progarm execution is started.The constructor had an arm which it could move about and which could be used to change the state of the cell at athe athe tip tip ,it ,it was was poss possib ible le to crea create te obje object ctss cons consis isti ting ng of regi region onss of the the two two dimensional cellular automata world which were fully specified by the program that controlled the constructor. The vonneumann’s kinematic constructor has had perhaps a greater influence,for it is a model of general manufacturing which can more easily be adapted to the three dimensional world in which we live.The robotic arm of constructor is moved in three space and which grasped parts from a sea of parts around it. These parts were then assembled into another kinematic constructor and
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17 it’s it’s associ associat ated ed contro controll comput computer er..
An impor importa tant nt point point to notice notice is that self self
replication,while important,is not by itself an objective.A device able to make copies of itself but unable to make anything else wouldnot be very valuable.Vonneumann’s proposals centered around the combination of a universal constructor,which could make make anythi anything ng it was directed directed to make,an make,and d a univer universal sal computer computer ,which ,which could could compute any thing it was directed to compute.It is this ability to make any of a broad range of structures under flexible programatic control that is of value.The ability of the device to make copies of itself is simply a means to achieve low cost rather than end in itself . BROADCAST ARCHITECTURE:
Molecular Constructor Macroscopic Computer Molecular Constructor
Molecular Constructor
In the Vonneumann’s architecture,Drexler’s assembler and in living systems the complete set of plans for the system are carried internally in some sort of memory.
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18 This is not a logical logical necessity in a general manufacturing manufacturing system. If we separate the constructor from the computer and allow many individual constructors to receive broadcast instructions from a single central computer then each constructor need remember the plans for what it is going to construct:it can simply be told what to do as it does it as shown in above figure.This approach not only eliminates the requirement for a central repository repository of plans with in the constructor,it can also eliminate almost all of the mechanisms involved in dec oding and interpreting those plans.The advantages of the broadcast architecture are : (1)It reduces the size and complexity of the self replicating component (2)It allows self self replicating component to rapidly redirect to build build something noval. (3)If (3)If the centra centrall comput computer er is macros macroscop copic ic and under under our direct direct control control,, the broadcast architecture is inherently safe in that the individual constructors lack sufficient capability to function autonomously.
3.2APPLICATIONS 3.2.1 Robotics
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19 Robotic surgical systems are being developed to provide surgeons with unprecedented control over precision instruments. This is particularly useful for minimally invasive surgery. Instead of manipulating surgical instruments, surgeons use their thumbs and fingers to move joystick handles on a control console to maneuver two robot arms containing miniature instruments that are inserted into ports in the patient. The surgeon’s movements transform large motions on the remote controls into micro-movements on the robot
arms
to
greatly
improve
mechanical
precision
and
safety.
A third robot arm holds a miniature camera, which is inserted through a small opening into the patient. The camera projects highly magnified 3-D images on a console to give a broad view of the interior surgical site. The surgeon controlling the robot is seated at an ergonomically designed console with less physical stress than traditional operating room conditions.
3.2.2 NANOROBOT DESIGN
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20 Virtual Reality was considered a suitable approach for nanorobot design and for the use of macro- and micro-robotics concepts given certain theoretical and practical aspects that Focus on its domain of application. The nanodevice design must be robust enough to operate in an aqueous environment with movement having six-degrees of freedom .The nanorobot design is derived from biological models and is comprised of components such as molecular sorting rotors and a robot arm (telescoping (telescoping manipulator ) . The nanorobot exteriors considered in our design assumes a diamondoid material to which may be attached an artificial glycocalyx surface that minimizes fibrinogen(and other bloodProtein) adsorption and bioactivity, thus ensuring sufficient biocompatibility for for the the nanor nanorobo obott to avoi avoid d immu immune ne syst system em atta attack ck Diff Differ eren entt mole molecu cule le type typess are are distinguished by a series of chemotactic sensors whose binding sites have a different affinity for each kind of molecule .Some concepts provided from underwater robotics were were assume assumed d for nanorob nanorobot ot locomo locomoti tion. on. The nanorob nanorobot ot kinema kinematic tic respons responsee can be predicted using state equations, positional constraints, inverse kinematics and dynamics, while some individual directional component performance can be simulated using control system models of transient and steady state response.
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Nanorobots sensing obstacles
Nanorobot obstacle avoidance
MANUFACTURING OF NANOROBOTS Molecular nanotechnology (MNT), the umbrella science of nanomedicine, envisions nanorobots manufactured in nanofactories no larger than the average desktop printer. The nanofactories would use nano-scale tools capable of constructing nanorobots to exacting specif specifica icatio tions. ns. Design Design,, shape, shape, size size and type type of atoms, atoms, molecul molecules, es, and comput computeri erized zed components included would be task-specific. Raw material for making the nanorobots would be nearly cost-free, and the process virtually pollution-free, making nanorobots an extremely affordable and highly attractive technology.
3.2.3 WORKING The nanorobots use a macro transponder navigational system, which may allow high posit position ional al acc accura uracy cy in eac each h nano nanorob robot’ ot’ss ori orient entati ation. on. Suc Such h a sys system tem mig might ht inv involv olvee externally generated signals from beacons placed at fixed positions outside the skin. Nanorobots will possess at least rudimentary two-way communication; will respond to acoustic signals; and will be able to receive power or even re-programming instructions from an external source via sound waves. A network of special stationary nanorobots might be strategically positioned throughout the body, logging each active nanorobot as it
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passes, and then reporting those results, allowing an interface to keep track of all of the devices in the body.
By using the nanorobot’s local perception as much as possible and by sending the fewest possible messages to other nanorobots, unnecessary communication between the agents is reduced, thus minimizing energy consumption by the nanorobots.A doctor could not only monitor a patient’s progress but change the instructions of the nanorobots in vivo to pr progr ogres esss to an anot othe herr st stag agee of he heal alin ing. g... .. Nan Nanor orobo obots ts sa sati tisf sfy y th thei eirr ene energ rgy y requirements via the chemical combination of oxygen and glucose, both of which are plentiful in the human body. Glucose or natural body sugars and oxygen might be a source for propulsion, and the nanorobot will have other biochemical or molecular parts depending on its task. When the task is completed, the nanorobots would be flushed from the body.
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3.3. CARBON NANOTUBES
The combination of remarkable mechanical properties and unique electronic properties of carbon nanotubes (CNTs) offers significant potential for revolutionary applications in elec el ectr troni onics cs dev devic ices es,, co comp mput utin ing g an and d da data ta st stor orag agee te tech chnol nolog ogy, y, se sens nsor ors, s, de dete tect ctor ors, s, nanoelectromechanical systems (NEMS), as tip in scanning probe microscopy (SPM) for imagi im aging ng an and d na nano noli lith thog ogra raph phy y an and d a nu numb mber er of ot othe herr ap appl plic icat atio ions ns.. Th Thus us th thee CN CNT T synthesis, characterization and applications touch upon all disciplines of science and engineer engi neering ing.. Thi Thiss tut tutori orial al wil willl pro provid videe an ove overvi rview ew of the fol follow lowing ing top topics ics:: CNT properties properties,, growt growth h techn techniques iques particularly particularly CVD and plasm plasmaa CVD, patterned growth,
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24 vertical verti cal alignm alignment, ent, appli applicatio cations ns in nanoel nanoelectro ectronics, nics, sensor sensors, s, fiel field d emis emission, sion, micro microscopy scopy and others.
Development of Silicon Carbide Nanotubes (SiCNT) for Sensors and Electronics Thee obj Th objec ecti tive ve of th this is ta task sk is to ev eval aluat uatee mu mult ltip iple le ap appr proa oach ches es to sy synt nthe hesi size ze and charact char acteri erize ze the hig highes hestt per perfor formin ming g Si SiCNT CNTss for hig high h tem temper peratu ature re & hig high h rad radiat iation ion conditions. Also to develop sophisticated modeling and simulation technologies that will facilitate the research and development of various chemical techniques for SiC-based nanotube (SiCNT) fabrication and to further expedite the design and prototyping of more complicated assemblies and devices made from SiCNTs. Multiple synthetic approaches are planned which parallel the direct CNT formation as well as an indirect approach involv inv olving ing derivati derivatizat zation ion of a CNT to a SiC SiCNT. NT. One ind indir irect ect approach approach tha thatt may be envisioned to produce a SiCNT, which can be thought of as a chemical derivative of a CNT, starts with a CNT that is modified by chemically attaching different Siliconcontaining functional groups to the CNT (functionalizing). This derivatized-CNT is then pyrolyzed in an appropriate environment to yield a SiCNT. A more direct approach would employ Chemical Vapor Deposition (CVD) using reduced partial-pressures of reactants and trace amounts of catalysts to directly obtain SiCNTs . This more direct fabrication attempt would rely on high temperature (2000°C) CVD using a catalytic (trace metal) substrate.
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25 Compared with theoretical SiCNT modeling results. The electrical properties include investigations into potential semiconductor properties that could be extended to higher (than (th an CNT CNT)) tem temper peratu atures res.. Onc Oncee fab fabri ricat cated, ed, the SiC SiCNTs NTs ele electr ctrica icall and mec mechan hanica icall properties would be characterized and Electrical activity of SiCNTs could also be studied as a function of adsorbates, which could ultimately lead to applications such as nano-gassensorss for harsh environments. sensor environments. Mechanical properties properties to be studi studied ed inclu include de tensi tensile le and compressive stress for structural components (e.g. actuators) and also their effect on SiCNT SiC NT ele electr ctrica icall pro proper pertie ties. s. Kno Knowle wledge dge gai gained ned fro from m the these se fab fabric ricati ation on res result ultss and empi em piri rical cal in inve vest stig igat atio ions ns ca can n be in incor corpor porat ated ed in into to th thee mo model delss of th thee si simu mula lati tion on environment to improve fidelity.
3.4. NANOMEDICINE 3.4.1The Promise of Nanomedicine
The ultimate promise of nanomedicin nanomedicinee is the eradication eradication of disease. disease. To accomplish accomplish this goal goal requ requir ires es the the conv conver erge genc ncee of nano nanote tech chno nolo logy gy and and biot biotec echn hnol olog ogy. y. In turn turn,, nanomed nanomedici icine ne is the conver convergenc gencee of many many discip disciplin lines: es: biolog biology, y, chemis chemistr try, y, physic physics, s, engineering and material science. The
eradication of disease involves in three subgoals
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26 1) Using nano-robots, nano-machines or other methods at the molecular level to search and destroy disease-causing cells 2) Same as above for the purposes of repairing damaged cells 3) Using pumps or similar technology at the molecular scale as a means of drug delivery Nanotechnology involves the creation and use of materials and devices at the level of molecules and atoms. As life itself creates and u ses molecular materials and devices, nanoscience will provide great insights in life science concepts, such as how molecular materials self-assemble, self-regulate, and self-destroy. Nanomedicine eventually will infiltrate virtually every field of medicine, if not every realm of human endeavor. Nano medicine may be defined as the monitoring, repair, construction and control of human human biolog biologica icall syste systems ms at the molecu molecular lar level, level, using using engine engineere ered d nanodevi nanodevices ces and nanostructures. A samp sample le list list of area areass cove covere red d by and and conv conver erge ged d with with nano nanome medi dici cine ne incl includ ude: e: Biotechnolog Biotechnology, y, Genomics, Genomics, Genetic Genetic Engineering Engineering,, Cell Biology, Biology, Stem Cells, Cloning, Cloning, Prosthetic Prosthetics, s, Cybernetic Cybernetics, s, Neural Medicine, Medicine, Dentistry Dentistry,, Cryonics, Cryonics, Veterinary Veterinary Medicine, Medicine, Biosensors, Biological Warfare, Cellular Reprogramming, Diagnostics, Drug Delivery, Gene Therapy, Human Enhancement, Imaging Techniques, Skin Care, Anti-Aging.
3.4.2 Nanomedical Issues
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27 Other nanomedical issues include sensory feedback, control architectures, cellular repair and destruction, replication, safety, biocompatibility, environmental interaction, genetic analysis, diagnosis and treatment. Treatment covers the full range of illness and disease, from from cardio cardiovas vascul cular ar to trauma trauma,, amputa amputatio tions ns to burns, burns, brain, brain, spinal spinal and other other neural neural injuries/diseases, nutrition, sex and reproduction, cosmetics and aging.
3.5. Devices Nan Nanod odev evic ices es
will will
supp supple leme ment nt
curr curren entt
micr micro o
devi device ces, s,
whic which h
incl includ udes es
micr microo-
electr electrome omechan chanica icall system systemss (MEMS) (MEMS),, microf microflui luidic dics, s, and microa microarra rrays. ys. Exampl Examples es of medical medical applic applicati ations ons includ includee biosen biosensor sorss and detect detectors ors to detect detect trace trace quantit quantities ies of bacteria, bacteria, airborne airborne pathogens, pathogens, biological biological hazards, hazards, and disease disease signatures, signatures, microflui microfluidic dic applications for DNA testing and implantable fluid injection systems and MEMS devices which which cont contai ain n mini miniat atur uree movi moving ng parts parts for for pacem pacemake akers rs and and surg surgic ical al devi device ces. s. MEMS stands for Micro Electronic Mechanical Systems, a technology used to integrate various electro-mechanical functions onto integrated circuits. A typical MEMS device combines a sensor and logic to perform a monitoring function.
3.6 OTHER APPLICATIONS KILLING CANCER CELLS
Given such molecular tools, we could design a small device able to identify and kill cancer cells. The device would have a small computer, several binding sites to determine the concentration of specific molecules, and a supply of some poison which could be selectively released and was able to kill k ill a cell identified as cancerous.
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28 The device would circulate freely throughout the body, and would periodically sample its environ envi ronmen mentt by det determ ermini ining ng whe whethe therr the bin bindin ding g sit sites es wer weree or wer weree not occ occupi upied. ed. Occupancy statistics would allow determination of concentration. Today's monoclonal antibodies are able to bind to only a single type of protein or other antigen, and have not proven effective against most cancers. The cancer killing device suggested here could incorporate a dozen different binding sites and so could monitor the concentrations of a dozen doze n dif differ ferent ent ty types pes of mol molecul ecules. es. The com comput puter er coul could d det determ ermine ine if the pro profil filee of concentrations fit a pre-programmed "cancerous" profile and would, when a cancerous profile was encountered, release the poison.
CONTROL OF POLLUTION THROUGH NANOTECHNOLOGY
Nanotechnologies have the potential to produce plentiful consumer goods with much lower throughout of materials and much less production of waste, thus reducing carbon dioxide buildup and reducing global warning. They also have the potential to reduce waste, especially hazardous waste, converting it to natural materials, which do not threaten life. Molecular manufacturing processes will rearrange atoms in controlled ways, and can neatly package any unwanted atoms for recycling or return to their source. This technology can also be used in the control of pollution due to orbital and nuclear wastes, cleansing soil and water, cleansing the atmosphere. Nanotechnology can help with the cleanup of these pollutants. Living organisms clean the environment, when they can, by using molecular machinery to break down toxic materials. Systems built with nanotechnology will be able to do likewise, and to deal with compounds that aren’t biodegradable.
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29 New imaging technologies will provide high quality images not currently possib possible le with with curren currentt device devices. s. This This allows allows greate greaterr surgic surgical al precis precision ion and target targeted ed treatment. Chasing cancerous cells or removing tumors can result in severely damaged normal tissue or the loss of abilities like hearing and speech as in the case of brain tumors. Nanotechnology can offer new solutions for the early detection of cancer and other other diseas diseases. es. Nanopro Nanoprobes bes can be used used with with magnet magnetic ic reson resonance ance imagin imaging g (MRI). (MRI). Nanoparticles with a magnetic core are attached to a cancer antibody that attracts cancer cells cells.. The The nano nanopar parti ticl cles es are are also also link linked ed with with a dye, dye, easi easily ly seen seen on an MRI. MRI. The The nanoprobes latch onto cancer cells and once detected by MRI, can then emit laser or low dosage killing agents that attack only the diseased cells. Miniature devices are also implan implantab table le for imagin imaging g not possib possible le curren currently tly.. A pill, pill, for instan instance, ce, can contain contain a miniature video system. When the pill is swallowed, it moves through the digestive system and takes pictures every few seconds. The entire digestive system can be assessed for tumors tumors,, bleedi bleeding, ng, and diseas diseases es in areas areas not accessi accessible ble withco withcolon lonosc oscopi opies es and endoscopies.
3.7 LIMITATIONS Nan Nano o tech techno nolo logy gy can can be disa disadv dvan anta tage geou ouss as all all thin things gs are. are. Rese Resear arch cher erss have have demonstrated that small systems behave dramatically, differently from large breaking the second second law of thermo thermodyn dynami amics cs and posing posing a major major challe challenge nge for those those develo developin ping g nanotechnology. The second law of thermodynamics states that closed systems remain the same or have an increase in entropy over time. A hot cup of coffee, for example, won't get hotter without intervention. But while this has proven true at the macro level, chemical physicists have shown it doesn't hold at the micro level, suggesting nanotechnology will be difficult to develop as anyth anythin ing g mode modell lled ed on larg largee syst system emss coul could d some someti time mess run run back backwa ward rdss .Als .Also o with with nanotechnolog nanotechnology y destructive destructive objects such as atomic atomic bomb grenades,nuclear grenades,nuclear weapons, weapons, robotic killers designed to kill humans etc.,can be made which can dump humanity in danger..
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TO HIT THE ROAD AHEAD Progress in the 21 st century will be 1000 times greater than in the 20th century in terms of technical change. Around 2030, we should be able to flood our brains with •
Nanobots that can be turned off and on, and which would function as ‘experience
beamers’ that allow us to experience the full range of other people’s sensory experiences too boring, we will have access to archives where more interesting experiences are stored. By 2030, non-biological thinking will be trillion of times more powerful than biological thinking. •
Desktop molecular computers could have the computational power of a million human
brains in terms of switching operations per second. Humanity will be faced with a powerful, accelerated social revolution as a result of nanotechnology. In the near future a team of scientists will succeed in constructing the first nanosiezed robot capable of self replication. Within a few short years and five billion trillion nano-robots later, virtually all the present industrial processes will be obsolete, along with our contemporary concept concept of labour labour.. Consum Consumer er goods goods will will become become plenti plentiful ful,, inexpen inexpensiv sive, e, smart smart and durabl durable. e. Medicine will take a quantum leap forward. Space travel and colonization will become safe and affordable. For these and other reasons, global lifestyles will change radically and human behaviour will be drastically impacted. The world is on the brink of a new technological revolution beyond any human experience. A new, more powerful industrial revolution capable of bringing wealth, health and education, without pollution, to every person on the planet is just around the corner. No long longer er need need will will fore forest st to be cut cut or smok smokee spew spewed ed into into the the air. air. This This is the the prom promis isee of Nanotechnology.
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CONCLUSION We can can neve nevert rthe hele less ss to say say our comi coming ng age age will will be a nano nanote tech chno nolo logy gy.. Addi Adding ng progr programm ammed ed positi positional onal contro controll existi existing ng method methodss gives gives us greate greaterr contro controll over the material world and improved our standards of living.
REFERENCES 1.Nano technology by Drexler 2.www.nanoword.net 3.www.nanotechbook.com
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