Molecular Nanotechnology By Kavitha, Boppana

Presentation Overview  Molecular Manufacturing  Positional Assembly  Self Replication  Visual Images  Development  Conclusion

Molecular Manufacturing Manufactured products are made from atoms Manufactured products are made from atoms properties of those products depend on how those atoms are arranged properties of those products depend on how those atoms are arranged  coal – diamond  sand + few other trace elements – computer chips  dirt + water + air – potatoes

Molecular Manufacturing should let us Molecular Manufacturing should let us  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.

Positional Assembly

Introduction  Right number in right place  Any small molecule can be synthesized by having skill and patience

The utility of diamond  Diamond is light and strong  Cannot be made economically  Graphite Vs Diamond  Greater thermal conductivity  Greater breakdown fields  Large pure crystals of diamond are scarce  Just more difficult today

Interest of the computer industry  Manufacturing cost,less than a dollar per pound  Operating at frequencies of tens of gigahertz or more  Linear dimensions for a single device of roughly 10 nanometers  high reliability  Energy dissipation of roughly 10^-18 joules per logic operation

The problem  Building a diamondoid electronic computer captures many of the fundamental issues  The issue of building large structures that cannot be made by regular repetition of some structure

How we make diamond today?  Using CVD methods  Diamond CVD growth involves highly reactive species  Defect structures  Two fundamental Mechanisms (1)abstration of hydrogen from diamond surface (1)abstration of hydrogen from diamond surface (2)interaction of carbon species (2)interaction of carbon species

Hydrogen abstraction tool for nanotechnology  Use of an alkynes radical tip  Ab initio quantum chemistry techniques  Thermal vibrations  Creating the radical in controlled vacuum setting should be feasible  Thermal, mechanical, optical and chemical energy

Applying positional control  Require tool to have certain properties to make synthesis reliable, feasible, practicable reliable, feasible, practicable (1)have the proper chemical properties (1)have the proper chemical properties (2)be relatively small (2)be relatively small (3)be capable of remaining chemically and mechanically stable (3)be capable of remaining chemically and mechanically stable (4) be bound to a system that can transfer forces and torques to the reactive portion of the tool (5)Be selective between alternative reactions and (6) Be easily made

Other requirements for Tool Use  Creating an inert environment  Very small very high quality vacuum  Diamondoid material  Diamondoid structures are very stiff  Objects that are manufactured are stiff

Selective Transport Across a Barrier  Diamondoid barrier to keep unwanted contaminants out  Get desired raw materials  Eject the spent tool  Rotor embedded  High affinity-low affinity  Result is to increase the concentration of the desired molecule  Can achieve extremely high purities

Self Replication

Self Replication and nanotechnology  Make products inexpensively  Inspired by living things  Artificial self replicating systems car – horse car – horse  Inflexible and brittle  Difficult to design a self replicate in a controlled environment

Complexity of self replicating systems  Von Neumann Figure 1. This

Drexler's architecture for an assembler

Complexity of self replicating systems (bits)  Von Neumann's universal constructor ~500,000  Internet worm (Robert Morris, Jr., 1988) ~500,000  Mycoplasma genitalium 1,160,140  E. Coli 9,278,442  Drexler's assembler ~100,000,000  Human ~6,400,000,000  NASA Lunar Manufacturing Facility over 100,000,000,000

Visual Images

Bearings

Differential Gear

Development  Molecular nanotechnology (MNT) will permit inexpensive construction of light, strong, smart materials that will revolutionize aerospace and other applications  Molecular medical devices that will revolutionize medicine  Inexpensive solar cells and batteries will eliminate our dependence on coal, oil and nuclear fuels

Conclusions  Achieve the first three objectives.  Difficult without using some form of positional assembly (to get the right molecular parts in the right places)  and some form of self replication (to keep the costs down).

References   puter.html puter.html puter.html  

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