PAPER PRESENTATION ON NANOTECHNOLOGY
Today mankind is facing many problems ranging from health issues to the environmental hazards in which he lives. If there is one technology which can rescue mankind, it is Nano – Technology. Nano – Technology by name itself means going smaller into things. It tries to manipulate the basic element of matter – atom. Nano – Technology takes its inspiration from nature. The philosophy of nature is to start creating from building blocks. This is exactly what Nano - Technology is striving to accomplish. Nano – Technology will have its own unique effect in every aspect of mankind. Its specialties range from treating cancer to reversing the process of ageing, from preventing global warming to blocking the ozone hole, from creating food to creating diamond from carbon. This technology is all set to bring about a revolution in the 21st century.
NANO – TECHNOLOGY HISTORY OF NANO – TECHNOLOGY AN ANALOGY NANO – TECHNOLOGY VS PRESENT TECHNOLOGY BASIC CONCEPT NANO SEARCH OUTCOMES SCANNING TUNNELLING MICROSCOPE ATOMIC FORCE MICROSCOPE
BASIC TECHNIQUES UNIVERSAL ASSEMBLER SELF – REPLICATION DISSEMBLERS
CONTROL UNIT MATERIALS USED CONSTRUCTIVE APPLICATIONS DESTRUCTIVE APPLICATIONS EXISTENCE OF NANO – TECHNOLOGY IN REAL WORLD THE ROAD AHEAD CONCLUSION
NANO – TECHNOLOGY: Nano – Technology is a hybrid science composing of engineering, physics, chemistry & biology. The word “Nano” which is referred to 10-9 which was a very small negligible value. Similarly Nano – technology is also a technology of going smaller in to things. Creation starts from basic fundamental units. If we know how these fundamental units are organized and a method to manipulate them then we can create wonders. This is what Nano – Technology does. HISTORY OF NANO – TECHNOLOGY: We all know that the basic fundamental unit of each and every matter is „atoms‟. Atoms and molecules stick together because they have complementary shapes that lock together. Albert Einstein first proved that each and every atom measures about a nanometer in diameter. In 1959 Richard P. Feynman predicted a technological world composed of self replicating molecules whose purpose would be the production of nano – sized objects. Almost hundred years after Einstein‟s insight and Feynman‟s initial
proposition, the nanometer scale looms large on the research agenda. Now the popular semi – conductor industry is edging closer to the world of Nano – Technology where components are miniaturized to the points of individual molecules and atoms. AN ANALOGY: Iron ore is a rugged hard rock by nature. But when one has the technology to break it into small pieces it‟s uses are limitless. Similarly a mountain of granite is of no use until it was broken into small stones. These small stones can be used to build any purposeful buildings. The concept is: when one goes down to the bottom of things he will discover so much possibilities and potential. This is exactly what Nano – Technology
is. Here one tries to go down to level of manipulating atoms, molecules and the chemical bonds between them. NANO – TECHNOLOGY VS PRESENT TECHNOLOGY: PRESENT – TECHNOLOGY NANO – TECHNOLOGY
Presently we follow „Top – Bottom approach‟. ex: if we want to design a chip we will choose a silicon crystal and we will slice it to attain the desired shape. There will be microscopic and atomic irregularities which can not be corrected.
The approach followed here is „Bottom – Top‟ . ex: atoms of silicon are assembled by suitable technique to attain desired wafer state. Those microscopic and atomic irregularities can be corrected on Atomic scale. Atomic scale: It means the “atom by atom , bond by bond manipulation”.
Strength of the product decreases according to the atomic and
extreme strength due minimization of these irregularities. The resulting product shrunks in size. Because we can create the bond where ever it is necessary and break the unnecessary bonds.
microscopic irregularities present in it. Size of the product is big. Since there may be millions and trillions of unwanted bonding.
It is not possible to create new materials with desired properties with present technology. Transistors
With this technology new types of materials with desired properties can be created. 100 nonometre is the upper end of nano – technology range. 4
generation of microprocessors, with
dimensions of the order of 100 nanometres.
It is fully true that the technology needed to achieve this atomic level is very complex. At present this technological level has not yet been achieved. So Nano – Technology is still in its infancy. It is only conceptual stage. There are so many predictions and possibilities. In today‟s scenario, Nano – Technology is in its infancy the concepts discussed below are just the predominant proposals that are being made by the scientists this day.
Nano – technology broadly refers to the manipulation of matter on the atomic and molecular scales, i.e., where the objects of interest are 0.1 – 100 nanometre in size. Just as one who builds a house brick by brick, the nanoist proposes to build novel materials of incomprehensible strength, atom by atom. Manipulation to the atomic bonds and atomic precision are the cornerstones of Nano – Technology i.e., creating bonds where ever it is necessary and break the bonds where ever it is unnecessary. As atoms come together to form molecules, and molecules come together to form inherent macro – scale properties are determined by controlling molecular structure in material synthesis, mankind has gained unprecedented control over the basic material properties, such as conductivity, strength, capacity, ductility and reactivity, yielding innovative applications ranging from batteries to automotive materials. This is a passive nano technique that primarily focuses on tuning the
properties of resulting bulk materials. The active nano technique facilitates creation of functional electronic and ultimately mechanical devices at the nano scale.
Nano technology is not just miniaturizing things. At nano – scale, different laws come into play. Properties of traditional materials change and the behaviour of surfaces starts to dominate the behaviour of bulk materials, opening up new realms.
In the electronics domain, the benefit of working on nano – scale is the production of smaller things. Currently, the semiconductor industry, which is expected to provide even smaller circuits and even more powerful computers, finds itself plunging towards a size barrier with existing technologies that are fundamentally limited by the wavelength of light, or other forms of electromagnetic radiations such as X – rays. Using nano tubes or other molecular configurations enables engineers to break through this barrier by working below the wavelength of light, X – ray, etc. the ultimate result is circuit elements consisting of single molecules.
NANO SEARCH OUTCOMES: Tools capable of imaging and manipulating individual atoms or molecules have ushered in the nano age. The icons of this revolution are scanning probe microscopes – the scanning tunneling microscope (STM) and the atomic force microscope(ATM) – capable of creating pictures of individual atoms or moving them from place to place. SCANNING TUNNELLING MICROSCOPE: IBM first invented the STM. The instruments key element is a fine metal needle or tip. The metal is usually tungsten, nickel, or gold. When this tip is moved very close to the surface of the object being scanned and a tiny voltage is applied, 6
the odd rules of quantum mechanics allow electrons to jump or “tunnel” across the remaining gap. Though very small, this flow of electrons can easily be detected experiments have demonstrated that the STM can be used to “etch” surfaces by blatting out single clumps of them with short busts of current. In some cases STM can be used to “herd” atoms across the sample surface. ATOMIC FORCE MICROSCOPE: IBM laboratory has mounted sharp, nano – scale tips used in atomic force microscopes on to microscopic cantilevers on a microchip. These tips touches the surface of the sample. The force of contact is very small. As with the STM the instrument is scanned across the sample surface to generate an image. Since the AFM senses the surface by “touch” it can write digital bits on a polymer sheet and offers a way to examine nonconducting materials such as biological molecules, plastics, ceramics and insulating materials like glass or diamond. This technique could lead to the
development of a data storage device with twenty times or more the memory density of today‟s best disk drives. Microchips which boast circuit lines of a little more than 100 nanometres, are about to become the most notable application areas. Once - conventional silicon electronics is likely to soon go bust and within 25 years nano electronics could replace it. Macro-scale machine systems being used in the industry can be shrunk to this entire mechanism including the conveyor belt to molecular level to form a nano - scale construction system with a variety of tools that could build almost anything, including copies of itself. BASIC TECHNIQUES: The basic technique is to build nanoscopic assemblers, which can create molecules from atoms and then device a method so that self replication of the assemblers is possible. UNIVERSAL ASSEMBLER: 7
A universal assembler is a microscopic factory that can manufacture necessary products molecule by molecule. Universal assemblers will have nanoscopic arms, conveyor belts and a nanoscopic computing system. The concept of universal assemblers is still in its infancy. Depending on the product the components of the universal assemblers may differ. An assembler with arms and the other such mechanical devices may produce a physical molecule. An assembler which has enzymes, amino acids and ribosomes as its main components may create an antibody to a virus. Universal assemblers are said to be Active Cell Aggregate(ACA) which consists of a range of polygonal faced cells which can slide over each other and can form different shapes to suit the necessity. ACA works atom – by – atom and molecule – by – molecule. So to create a material consisting of billions of atoms. It takes a lot of time. So to speed up this process a technique has been formulated called self – replication. SELF – REPLICATION: Self – replication is a process by which assemblers create many other assemblers like themselves. This process speeds up the creation of a new material as the number of assemblers increases exponentially with time. Simultaneous processing of the desired material by millions of assemblers is possible. “with self – replication you build your transistors in a pot, a year‟s supply at a time”. Replication is a phenomenon of life. We find it in all living organisms. Cell division is replication. The nanoists are trying to gain an inspiration from living cells just as man tried to get inspiration from a bird to be able to fly. Replicators may be assumed to be factories shrunk to the size to a cell. Just as DNA provides information for the biological cells to replicate, it has been proposed that
information about replication can be provided to the replicators by means of chains of polymerized molecules(data tapes) with some codes in the form of some irregularity. Speed of replication will depend on the size of the unit and the structure. Replication is an exponential growth in number of assemblers. There must also be some means of controlling replication either by the use of data tapes (synthetic polymers carrying information ) or by some external means such as electromagnetic waves. Without such effective measures of controlling replication, it can prove to be disastrous. DISSEMBLERS: Dissemblers are also microscopic factories like the assemblers. But they are the opposite of the assemblers. The job of the dissemblers is to dissemble the assemblers once its job is over. The assemblers assemble the product and the replicators replicate more and more assemblers to quicken the time of production. So once the product has been fully assembled, the assemblers will be of no use and they will have to be disabled. It is for this purpose the dissemblers are used. The dissemblers will break the bonds between the atoms of the assemblers and hence they will be dissembled to junk atoms. CONTROL UNIT: In operations so nanoscopic as this co – ordination between the different assemblers, replicators and dissemblers must be robust. There are many proposals for the control unit. One proposal suggests that there has to be macroscopic control unit outside the working environment to co – ordinate the actions of the assemblers, dissemblers and replicators. The communication medium between the control unit and the constituents could be electromagnetic waves. Another proposal suggests the presence of nanoscopic control units inside each and every constituent so that the constituents can be programmed to perform the particular task. In this case communication between the individual units may be some form of polypeptide chains with some irregularities which carry coded information. 9
MATERIALS USED: Materials used for the manufacture of the individual units may differ depending on the requirements. For example if an enzyme has to be created from the assemblers, dissemblers and replicators may be made of proteins, amino acids, tissues, mitochondria, vessels and other bio – chemical materials. The proteins could serve as building blocks, the mitochondria could serve as energy producing elements and the vessels could serve as conveyor belts etc.. on the other hand if a nanoscopic transistor has to be created, the building blocks of the individual units will be totally different. As the C60 atoms are extremely strong they could be used to produce nano gear wheels and conveyor belts and so on.
CONSTRUCTIVE APPLICATIONS: If human bones can be coated with biosynthetic material of immense strength, damage to the bones will be impossible. If diamond can be easily produced from carbon and its applications in almost all fields will be unending. If a Nano robot can be produced which can attach itself to the HIV virus, AIDS will become completely curable. If air borne Nano robots are able to convert O2 to O3, the problem of ozone layer can be easily tackled. If Nano robots can manufacture any food from any other material, the problems of starvation will see an end. If petroleum could be created from carbon and hydrogen, all insufficiencies in energy can be sorted out. 10
The list goes unending …………
DESTRUCTIVE APPLICATIONS: The dark side is equally astounding. Replicators have the capacity of exponential increase in number. This sort of replication is left uncontrolled. It can have disastrous effects on nature. If Nano robots can in no time break down any material may be by breaking bonds between molecules, the Nano robots can in no time breakdown any material into free molecules and atoms with no chemical bonds. A collection of Nano robots directed at a ship or any target with information to break bonds between atoms could in no time destroy it. EXISTENCE OF NANO – TECHNOLOGY IN REAL WORLD: An Israel company has developed a pill size video camera that can travel through the digestive track and transmit pictures along the way, providing a less invasive technique to examine the small intestine. This video camera uses a miniature CMOS video imaging chip and white LED as a light source. BELL labs USA has designed a transistor with an active switching layer of one molecule thick. Researchers at cornell university created the worlds smallest guitar of size 2 micron carved out of crystalline silicon using an Atomic Force Microscope.
IBM researchers have harnessed 10 µm carbon nano tubes using ultraline threads that are one five – hundredth the width of today‟s silicon transistors. These nano gadgets can measure temperatures between 50˚c and 500˚c and can
be used in a variety of micro environment. Scientists continue to create uses for these tiny tubes. Miniature machines of the size of computer chips, known as micro electromechanical systems(MEMS), are being used alongside or in place of microprocessors in a variety of ways. Examples include tiny MEMS mirrors in communications. MEMS - based switches control paths of light waves through fibre - optic networks. Phaedon Avouris and his team of researchers at IBM have succeeded in wiring up a working computer circuit within a single carbon nanotube was transistors in first placed over gold electrodes insulated nanotube. The two p-type
series. Then an
layer was laid, with subsequent
opening up of a window in the layer to expose part of the nanotube. Potassium was passed through the window, transistor. Sandwiching several non-magnetic layers less than a nanometer thick between magnetic layers has resulted in sensors for disk drives. Introduced in 1997 , these magneto restrictive heads are an enabling technology for the multibillion dollar storage industry. Albert Chang and his research colleagues at Purdue University, USA, have successfully linked two quantum dots, which are essentially flat pools of electrons measuring a mere 180 nanometres. Even nanowires developed using standard electron beam lithography can function as switches for quantum computers that can be switched on/off or in a combination of states depending on the type of spin. Cees Dekkar and his research team at Delft University of Technology in the Netherlands have developed logic circuits comprising FETs comprising FETs 12 converting p-type transistor to n-type
carbon nanotubes. Logic
(component transistors) fabricated from semiconducting silicon and galliumnitride nanowires amplify signals with an output-to-input ratio much greater than 1.Each transistor is controlled by its own local gate contact. The Delft research team developed a new transistor layout that offered options of coupling various transistors on a single chip. This process enabled assembly of logic circuits. This also facilitates construction of NOR, SRAM and AC ring oscillator circuits for basic computation. Harvard University engineers have developed faster and smaller chips using tiny crystal rods of silicon and other semiconductors called super fast chips. Prof. Charles M. Lieber, who leads the research at Haward University, reveals that these chips were built. Out of a droplet of solvent saturated with silicon or gallium nitride. Practical computer chips using nanowires are likely to be developed in the near future. Dr. Lieber reveals that in a year or two, such nanowire transistors could be used as biological sensors by attaching them to specific molecules. A periodic array of C60 molecules encapsulated nanotube(SWNT) generates a hybrid in a single-wall carbon of
electronic hand, a derivative
nanotube‟s states and c60 molecular orbitals. Although the embedded molecules can modify the electronic properties of the nanotube, the tube‟s atomic structure remains unchanged. Carbon nanotube (CNT) is a new form of carbon, configurationally equivalent to two dimensional graphene sheet rolled into a tube. It is grown now by several techniques in the laboratory and is just a few nanometers in diameter and several microns long. CNT exhibits extraordinary mechanical properties: the Young's modulus is over 1 Tera Pascal. It is stiff as diamond. The estimated 13
tensile strength is 200 Giga Pascal. These properties are ideal for reinforced composites, nanoelectromechanical systems (NEMS).
Sequence of STM images of the ten molecules that were moved precisely along a step one atom high on a copper surface, representing the numbers from zero to ten. The molecules are moved similar to the beads of an abacus.
Pentium – IV processors from INTEL has a phenomenol 44 million transistors embedded on a single chip. The company claims that its Prescott is going to be the fastest with neat architecture(speed 5 GHZ, with 13 new instructions).
According to MOORE‟s law the number of transistors on a chip doubles every 18 months. This is where Nanotechnology comes into the picture
Labonte, Home-built UHV STM have developed atmoically flat Au (gold) film.
Nanotubes emit electrons at a relativity low voltage, which translates to minimal power requirements while maintaining high current densities. These characteristics encouraged to generate microwaves using nanotube field
emission with implications for wireless communications. Cell phones typically send a weak signal to a local base station, where microwave amplifiers beef up that signal. The stability of nanotubes enables smaller cellular base stations with a longer working life.
Field emission is the driving force behind flat – panel displays. A deep belied CTV or computer monitor relies on a big gun to shoot electrons at the pixels of a phosphor screen ,which light up accordingly. Millions of nanotubes arranged just below the screen can substitute these bulky and expensive electronic guns.
In 1998, Israeli scientists demonstrated that DNA could be coated with silver and made to conduct electricity.
The „smart shirt developed by sensatex, monitors the vital signs of those involved in high – stress occupations. The parameters monitored are heart rate, respiration rate, body temperature and calorie burn rate.
THE ROAD AHEAD: Nanotechnology, though mostly confined to laboratory set-ups at present, promises to revolutionize electronics in the coming decades . it finds applications in several fields, including mechanical engineering, biology, process technologies, medical sciences and so on. CONCLUSION: All this proves beyond doubt that Nano – Technology has the potential to revolutionize the way of life. Taking into account the obstacles in the path of realization of the goal. It is supposed that Nano – Technology will be in a definite and commercial form only by 2030. Mankind has witnessed many revolutions, from Stone age to Industrial age 21st century will witness a change from industrial age Nano age, Just as industrial revolution had its effect in every part of man‟s life. Nano – Technology will have its unique effect in every part of man‟s life. Nano – Technology will no doubt be the most promising of all technologies of the 21st century. Nano – Technology is likely to be adopted to miniaturize human being to counter the huge population by the next century.