NANOTECHNOLOGY ( Molecular or NANO- Manufacturing)


The idea of molecular manufacturing is based on the concept of scaling which is hence required to be deeply studied the various concepts for nano based manufacturing have been developed or proposed as a hypothesis. The main concepts with which we deal in this paper are the basic concept of nanotechnology and further the idea of making a basic nano factory, the problem faced due to scaling and various methods and assumptions that can lead to the formation of a feasible nano factory. The performance of advanced products, and some likely applications, are discussed. Finally, considerations and recommendations for a targeted development program are presented.

Introduction :-

What is Nanotechnology?

Technology as said is something which is primarily an application of scientific knowledge for carrying out the production of a product profitably and economically.
And as an important upcoming issues which is coming up is the environment factor so it should also meet and taken into consideration. Nanotechnology as said is the technology that deals with nanoscale (1nm-10-9m) its quite obvious that we are here talking about thing or specifically tools and machinery and production at atomic and molecular level. Although the literature of nanotechnology may refer to nanoscale machines, even "self-replicating machines built at the atomic level" , it is admitted that an "assembler breakthrough" will be required for this to happen. As a matter of fact a nano scale machine rarely exist. The major problem with the nano scale handling is the laws of classical physics cant be directly applied and the physical behaviour at the nanometer scale is predicted accurately by quantum mechanics, represented by Schrodinger's equation. Schrodinger's equation provides a quantitative understanding of the structure and properties of atoms

Scaling:-

Scaling tends to the most important topic amongst the various topic of concern in the field of nanotechnology. As the entire concept of nano production relies on the idea of scaling it is of great intrest. As its known that the when we are talking about nano scales atoms and molecules are to be talking into consideration and for information purpose the size of an atom is about (0.1nm) therefore to work in that scale it requires great precision and accuracy in addition to this a very important factor that is present there is the change in physical properties like resonant frequency.

1 mm - 10 nm :- "classical scaling"

Plenty of room at the bottom

Think of reducing the scale of working devices and machines from lmm to lnm, six
orders of magnitude! Over most of this scaling range, perhaps the first five orders of
magnitude, down to 10 nm (100 Angstroms), the laws of classical Newtonian physics
may well suffice to describe changes in behaviour. This classical range of scaling is so large, and the changes in magnitudes of important physical properties, such as resonant frequencies, are so great, that completely different applications may appear.

lecture by Richard Feynman

A suitable example to understand the problem of scaling

Strength and mass are completely different kinds of thing, and can't be directly compared. But they both affect the performance of systems, and they both scale in predictable ways. Scaling laws can compare the relative performance of systems at different scales, and the technique works for any systems with the relevant properties—the strength of a steel cable scales the same as a muscle. Any property that can be summarized by a scaling factor, like weight ~ L^3, can be used in this kind of calculation. And most importantly, properties can be combined: just as strength and weight are components of a useful strength-per-weight measure, other quantities like power and volume can be combined to form useful measures like power density.
An insect can move its legs back and forth far faster than an elephant. The speed of a leg while it's moving may be about the same in each animal, but the distance it has to travel is a lot less in the flea. So frequency of operation ~ L^-1. A machine in a factory might join or cut ten things per second. The fastest biochemical enzymes can perform about a million chemical operations per second.
Power density is a very important aspect of machine performance. A basic law of physics says that power is the same as force times speed. And in these terms, force is basically the same as strength. Remember that strength ~ L^2. And we're assuming speed is constant. So power ~ L^2: something 10 times as big will have 100 times as much power. But volume ~ L^3, so power per volume or power density ~ L^-1. Suppose an engine 10 cm on a side produces 1,000 watts of power. Then an engine 1 cm on a side should produce 10 watts of power: 1/100 of the ten-times-larger engine. Then 1,000 1-cm engines would take the same volume as one 10-cm engine, but produce 10,000 watts. So according to scaling laws, by building 1,000 times as many parts, and making each part 10 times smaller, you can get 10 times as much power out of the same mass and volume of material. This makes sense—remember that frequency of operation increases as size decreases, so the miniature engines would run at ten times the RPM.

Chris Phoenix, CRN Director of Research
Posted on August 03, 2004 in Science & Technology

MOORE’S LAW

*The empirical observation that the transistor density of integrated circuits doubles every 2 year

Introduction to Molecular manufacturing (NANOFACTORIES):.-

The whole concept of molecular manufacturing revolves around the idea of making more precies (Atomic level of precision) products which are more reliable for the purpose of molecular based manufacturing a system of tools and techniques has to be designed to carry out the task. Molecular Manufacturing has basically classified in 3 divisions:-

1. MAIN TYPE OF MOLECULAR MANUFACTURING
2. EXPONENTIAL BASED MANUFACTURING
3. COMBINED OR INTEGRATED TYPE OF MANUFACTURING

The basic type or the main type of manufacturing :

In this sort of manufacturing process its like individually and digitally controlling each and every part of the product being constructed . To date, many nanotechnology efforts have been content to achieve nanoscale—but not atomic—precision, or to build large quantities of small identical molecules. However, there are some technologies that are on the verge of achieving the goal.

Liao and Seeman have built a nanomachine out of DNA2 that can guide the construction of any of several different strands of DNA; the product sequence can be chosen by “programming” the machine with other DNA strands. This is a demonstration of programmable molecular fabrication. A planned extension to the machine would allow it to build longer and more interesting strands. Although this machine does not select from among multiple sites for the reaction, it does select from among multiple potential reactants, and its product has a precise and programmable molecular structure. Aono3 developed the ability to transport individual silicon atoms from one place to another in a covalent crystal, and was even able to automate this to make two dimensional patterns. Several other researchers have also used electricity (fields and/or currents) with scanning probe microscopes to implement reactions at sites chosen with atomic precision. Hersam4 has removed single selected hydrogen atoms from silicon at room temperature. Oyabu5 has removed and replaced single silicon atoms with purely mechanical force, but has not yet reported the ability to build multi-atom patterns.

2 Liao S, Seeman NC. (2004). “Translation of DNA signals into polymer assembly instructions.” Science
306(5704):2072-4
3 See the group's website at http://www.jst.go.jp/erato/project/agsh_P/agsh_P.html
4 R. Basu, N. P. Guisinger, M. E. Greene, and M. C. Hersam, “Room temperature nanofabrication of
atomically registered heteromolecular organosilicon nanostructures using multistep feedback controlled
lithography,” Appl. Phys. Lett., 85, 2619 (2004). See http://www.northwestern.edu/univrelations/
media_relations/releases/2004/09/molecular.html
5 Noriaki Oyabu, Óscar Custance, Insook Yi, Yasuhiro Sugawara, and Seizo Morita. (2003). “Mechanical
vertical manipulation of selected single atoms by soft nanoindentation using a near contact atomic force
microscope” Phys. Rev. Lett. 90, 176102. See http://link.aps.org/abstract/PRL/v90/e176102 and
http://focus.aps.org/story/v11/st19

The speed with which a molecular manufacturing tool can create its own mass of product may be called “relative productivity.” .These types of manufacturing processes are carried out using scanning probe microsopes and electron microscopes and as it can be well calculated that if it takes 1sec to carry out one operation then which can be a deposition of a carbon atom therefore it would take a approx. 6 billion yrs to fabricate its own mass. Therefore this idea of indiviusal based manufacturing is not feasible as it lacks by the time factorand as a concept we take in the idea of

Information delivery:-

The scaling of operation speed indicates that to embody information in the manufactured product via rapid physical manipulation, it will be necessary to use small actuators. Inkjet printers represent a step in this direction; their print head actuators are a few microns in size, and they can deliver megabytes per second. Furthermore, an inkjet printer can print its weight in ink in about a day. IBM's Millipede, a MEMS-based highly parallel scanning probe microscope array, can modify a substrate rapidly enough to be a serious candidate for computer data storage. Both of these technologies produce only two-dimensional “product,” but inkjet technology has been adapted to form three dimensional products, and scanning probe arrays have been used for dip-pen nanolithography (DPN). Nanoscale actuators, being smaller, will be able to operate faster and handle higher data rates. As information is required at a very high speed to compensate with the manufacturing process the concept of small embedded computers can also be applied to feed these nanofactories

Exponential manufacturing:-

In this process nano modules are implemented to carry out the construction of the final product. As its well known from the stated concept of scaling that the frequency of any operation increases when its shrunk down to a smaller level therefore for attaining high speed production of molecular manufacturing. Hences a small nano-factory established to manufacture parts of the product can be assumed and as faster solution. The goal of building functional manufacturing systems implies that the newly built systems must be controllable. Many types of control can be broadcast, including chemicals, photons, pressure, and electric or magnetic fields. Electric current is harder to broadcast, but systems too small to be contacted via micromanipulation could self assemble to electrodes. Electrical control may ultimately be the fastest and most flexible approach.

The various techniques developed for carrying out this type of manufacturing are;-

Polymer technique:-

This techniques basically involves the making of patterns by folding strands of RNA and DNA accordingly into desired shapes
Polymer chemistry is known to be quite versatile, and it should be possible to incorporate molecular actuators to select the polymer sequence; this would be faster and probably more reliable than using DNA strands to program the device. Molecular actuators can be controlled and powered by light, electricity, or changes in the composition of the solution.7

Bulk controlled polymerization techniques, such as DNA synthesis, often use two
repeated steps: first they make the end of the polymer reactive by “deprotecting” it, then add a monomer that is protected from further deposition. Nanoscale controlled
polymerization could control either the timing of the deprotection step or the monomer selection for the polymerization step. Or the system could protect the addition site by steric hindrance. Alternatively, it could use a polymerization reaction that is exothermic but has a high barrier, and accelerate the desired reaction—possibly by many orders of magnitude8—by holding the monomer in place. The ratio of reaction rates of confined and unconfined monomers will approximate the error rate

7 “Depending on the type of rotaxane setup, the stimuli can be chemical, electrochemical, or photochemical.” C.
Mavroidis, A. Dubey, and M.L. Yarmush. (2004). Annu. Rev. Biomed. Eng. 2004. 6:10.1–10.33.
http://www.bionano.neu.edu/AR220-BE06-10_001-033_.pdf
8 Creighton, T. E. (1984) Proteins. New York: W. H. Freeman and Company. Creighton lists one
intramolecular reaction with an effective concentration of 3.3x109. See discussion in Nanosystems 8.3.3a.
(Drexler, 1992, Nanosystems, Wiley)

Solid built in solution:-

Instead of making strands of desired shapes we can make small blocks at molecular level and then assemble them with the help of hydrogen bonds and cross linking.

Solid built in machine phase/ Mechanosynthesis:-

In this type of process all the reaction procedures are taking in controls by physical or mechanical procedures. Mechanosynthesis can reduce the rate of unwanted side reactions by preventing the reactants from contacting each other in ways that would allow those reactions to happen. This allows a particular deposition site to be selected from among many chemically similar sites. Engineered heterogeneous products can be built by mechanosynthesis that would be nearly impossible to build by self-assembly or common solution chemistry.

Some applications:-

Electron microscopes

Electron microscopes can image with near-atomic resolution. They can be used to cut
carbon nanotubes, even to trim outer tubes from multiwalled tubes14. They can also
deposit a variety of materials from gas feedstock (electron beam induced deposition,
EBID). These deposits have a feature size as small as 10 nm and can form threedimensional structures.15

Sub-wavelength imaging

FRET (fluorescence resonance energy transfer, which is very sensitive to nanoscale
distance) can be used to determine relative positions16. NanoSight has developed an
imaging system that can be placed in an existing optical microscope and image 20 nm
particles17. AngstroVision has claimed to be developing 3D nm-scale imaging using
visible light.18 A paper at NASATech claims that imaging below the diffraction limit
should be possible with incoherent light.19

Ion etching

Ion etching systems can achieve single-atom accuracy and can use tiltable workpieces.20 This may enable production of freestanding (undercut) kinematic structures from high performance materials that might be useful for research into nanoscale machinery or even as nanoscale molecular manufacturing systems.

14 http://www.berkeley.edu/news/media/releases/2000/07/27_nano.html
15 http://www.nims.go.jp/hvems/nano_char/facilities/facility6/NanofabSEM_e.html
16 http://www.iscid.org/encyclopedia/Fluorescense_Resonance_Energy_Transfer
17 http://www.nanosight.ukideas.com/
18 http://www.parc.com/cms/get_article.php?id=223
19 “Parallel-Beam Interferometry With Incoherent Light”
http://www.nasatech.com/Briefs/Sept00/NPO20687.html
20 Personal communication, Sakhrat Khizroev, December 2004

Conclusion:-

Various technologies develop so far and being developed promote the idea that the idea of nano scaling the production line would lead to higher , faster precise and more cheaper rate of production. This pare presents the basic types of techniques laid down by the various research groups. Another aspect of the these nanofactories can be that their development in higher respect can lead to creation of self developing hardware that can be smart and can use there own technology to develop them self’s and creating some product which is more efficient than the previous one.

References:-

Developing Molecular Manufacturing
Chris Phoenix, Director of Research, Center for Responsible Nanotechnology

Molecular Manufacturing: What, Why and How
Chris Phoenix, Director of Research, Center for Responsible Nanotechnology
www.Wikipedia.org

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