Whither nanotechnology
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Whither nanotechnology?. Ralph C. Merkle Distinguished Professor of Computing Georgia Tech College of Computing. Web pages. www.foresight.org. www.zyvex.com/nano. www.nano.gov. Health, wealth and atoms. Arranging atoms. Flexibility Precision Cost. Richard Feynman,1959.

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Whither nanotechnology

Whither nanotechnology?

Ralph C. Merkle

Distinguished Professor of Computing

Georgia Tech College of Computing


Whither nanotechnology

Web pages

www.foresight.org

www.zyvex.com/nano

www.nano.gov


Whither nanotechnology

Health, wealth and atoms


Arranging atoms

Arranging atoms

  • Flexibility

  • Precision

  • Cost


Whither nanotechnology

Richard Feynman,1959

There’s plenty of room

at the bottom


1980 s 1990 s

1980’s, 1990’s

Experiment and theory

First STM

By Binnig and Rohrer


President clinton 2000

President Clinton, 2000

“Imagine the possibilities: materials with ten times the strength of steel and only a small fraction of the weight -- shrinking all the information housed at the Library of Congress into a device the size of a sugar cube -- detecting cancerous tumors when they are only a few cells in size.”

The National Nanotechnology Initiative


Whither nanotechnology

The goal

Arrangements of atoms

.

Today


Whither nanotechnology

The goal

The goal

.


Whither nanotechnology

Positional assembly


Whither nanotechnology

Experimental

H. J. Lee and W. Ho, SCIENCE 286, p. 1719, NOVEMBER 1999


Whither nanotechnology

Theoretical


Whither nanotechnology

Molecular mechanics

  • Manufacturing is about moving atoms

  • Molecular mechanics studies the motions of atoms

  • Molecular mechanics is based on the Born-Oppenheimer approximation


Whither nanotechnology

Born-Oppenheimer

The carbon nucleus has a mass over 20,000 times that of the electron

  • Moves slower

  • Positional uncertainty smaller


Whither nanotechnology

Born-Oppenheimer

  • Treat nuclei as point masses

  • Assume ground state electrons

  • Then the energy of the system is fully determined by the nuclear positions

  • Directly approximate the energy from the nuclear positions, and we don’t even have to compute the electronic structure


Whither nanotechnology

Hydrogen molecule: H2

Energy

Internuclear distance


Whither nanotechnology

Hydrocarbon machines


Whither nanotechnology

Molecular machines


Whither nanotechnology

Theoretical


Whither nanotechnology

Thermal noise

σ:mean positional error

k: restoring force

kb: Boltzmann’s constant

T:temperature


Whither nanotechnology

Thermal noise

σ:0.02 nm (0.2 Å)

k: 10 N/m

kb: 1.38 x 10-23 J/K

T:300 K


What to make

What to make

Diamond physical properties

PropertyDiamond’s valueComments

Chemical reactivityExtremely low

Hardness (kg/mm2)9000CBN: 4500 SiC: 4000

Thermal conductivity (W/cm-K)20Ag: 4.3 Cu: 4.0

Tensile strength (pascals)3.5 x 109 (natural)1011 (theoretical)

Compressive strength (pascals)1011 (natural)5 x 1011 (theoretical)

Band gap (ev)5.5Si: 1.1 GaAs: 1.4

Resistivity (W-cm)1016 (natural)

Density (gm/cm3)3.51

Thermal Expansion Coeff (K-1)0.8 x 10-6SiO2: 0.5 x 10-6

Refractive index2.41 @ 590 nmGlass: 1.4 - 1.8

Coeff. of Friction0.05 (dry)Teflon: 0.05

Source: Crystallume


Making diamond today

Making diamond today

Illustration courtesy of P1 Diamond Inc.


Whither nanotechnology

Hydrogen abstraction tool


Other molecular tools

Other molecular tools


Some journal publications

Some journal publications

  • Theoretical Analysis of Diamond Mechanosynthesis. Part I. Stability of C2 Mediated Growth of Nanocrystalline Diamond C(110) Surface, J. Comp. Theor. Nanosci. 1(March 2004), Jingping Peng, Robert A. Freitas Jr., Ralph C. Merkle. In press.

  • Theoretical Analysis of Diamond Mechanosynthesis. Part II. C2 Mediated Growth of Diamond C(110) Surface via Si/Ge-Triadamantane Dimer Placement Tools, J. Comp. Theor. Nanosci. 1(March 2004). David J. Mann, Jingping Peng, Robert A. Freitas Jr., Ralph C. Merkle, In press.

  • Theoretical analysis of a carbon-carbon dimer placement tool for diamond mechanosynthesis, Ralph C. Merkle and Robert A. Freitas Jr., J. Nanosci. Nanotechnol. 3 June 2003. (Abstract)

  • A proposed "metabolism" for a hydrocarbon assembler, Nanotechnology8 (1997) pages 149-162.

  • Theoretical studies of reactions on diamond surfaces, by S.P. Walch and R.C. Merkle, Nanotechnology9 (1998) pages 285-296.

  • Theoretical studies of a hydrogen abstraction tool for nanotechnology, by Charles Musgrave, Jason Perry, Ralph C. Merkle and William A. Goddard III; Nanotechnology 2 (1991) pages 187-195.


Whither nanotechnology

Self replication

A redwood tree

(sequoia sempervirens)

112 meters tall

Redwood National Park

http://www.zyvex.com/nanotech/selfRep.html


Whither nanotechnology

Self replication

The Von Neumann architecture

Universal

Computer

Universal

Constructor

http://www.zyvex.com/nanotech/vonNeumann.html


Whither nanotechnology

Self replication

Drexler’s proposal for an assembler

http://www.foresight.org/UTF/Unbound_LBW/chapt_6.html


Whither nanotechnology

Exponential assembly


Whither nanotechnology

Convergent assembly


Self replication

Self replication

Kinematic Self-Replicating Machines (Landes Bioscience, 2004, in review).

Reviews the voluminous theoretical and experimental literature about physical self-replicating systems.

Freitas and Merkle


Whither nanotechnology

Replication

Manufacturing costsper kilogramwill be low

  • Today: potatoes, lumber, wheat, etc. are all about a dollar per kilogram.

  • Tomorrow: almost any product will be about a dollar per kilogram or less. (Design costs, licensing costs, etc. not included)


Impact

Impact

The impact

of a new manufacturing technology

depends on what you make


Impact1

Impact

Powerful Computers

  • We’ll have more computing power in the volume of a sugar cube than the sum total of all the computer power that exists in the world today

  • More than 1021 bits in the same volume

  • Almost a billion Pentiums in parallel


Impact2

Impact

Lighter, stronger,

smarter, less expensive

  • New, inexpensive materials with a strength-to-weight ratio over 50 times that of steel

  • Critical for aerospace: airplanes, rockets, satellites…

  • Useful in cars, trucks, ships, ...


Whither nanotechnology

Impact

  • 50x reduction of structural mass

  • Cost per kilogram under a dollar

  • Reducing cost to low earth orbit by 1,000 or more

  • http://science.nas.nasa.gov/Groups/

  • Nanotechnology/publications/1997/

  • applications/


Impact3

Impact

Size of a robotic arm

~100 nanometers

8-bit computer

Mitochondrion

~1-2 by 0.1-0.5 microns


Scale

Scale

Mitochondrion

Size of a robotic arm ~100 nanometers

8-bit computer

“Typical” cell: ~20 microns


Whither nanotechnology

Provide oxygen


Whither nanotechnology

Digest bacteria


Whither nanotechnology

Digest bacteria


Survey of the field

Survey of the field

Nanomedicine

  • Surveys medical applications of nanotechnology

  • Volume I (of three) published in 1999

  • Robert Freitas, Zyvex

http://www.foresight.org/Nanomedicine


Whither nanotechnology

Global Security

Military applications of molecular manufacturing have even greater potential than nuclear weapons to radically change the balance of power.

Admiral David E. Jeremiah, USN (Ret)

Former Vice Chairman, Joint Chiefs of Staff

November 9, 1995

http://www.zyvex.com/nanotech/nano4/jeremiahPaper.html


Whither nanotechnology

Overview

Core molecular

manufacturing

capabilities

Products

Products

Products

Products

Products

Products

Products

Products

Products

Products

Products

Products

Today

Products

Products

Products

Products

Products

Products

Products

Products

Products

Products

Products

Products

Products


Whither nanotechnology

How long?

  • Correct scientific answer: I don’t know

  • Trends in computer hardware suggestive

  • Beyond typical 3-5 year planning horizon

  • Depends on what we do

  • Babbage’s computer designed in 1830’s


Research objectives

Research objectives

Goals

  • Mechanosynthesis

    H abstraction, Carbene insertion, …

  • System design

    assemblers, robotic arms, …


Whither nanotechnology

Nanotechnology offers ... possibilities for health, wealth, and capabilities beyond most past imaginings.

K. Eric Drexler


Whither nanotechnology

Quantum uncertainty

σ2:positional variance

k: restoring force

m: mass of particle

ħ:Planck’s constant divided by 2π


Whither nanotechnology

Quantum uncertainty

  • C-C spring constant:k~440 N/m

  • Typical C-C bond length:0.154 nm

  • σ for C in single C-C bond:0.004 nm

  • σ for electron (same k):0.051 nm


Whither nanotechnology

Molecular mechanics

  • Internuclear distance for bonds

  • Angle (as in H2O)

  • Torsion (rotation about a bond, C2H6)

  • Internuclear distance for van der Waals

  • Spring constants for all of the above

  • More terms used in many models

  • Quite accurate in domain of parameterization


Whither nanotechnology

Molecular mechanics

Limitations

  • Limited ability to deal with excited states

  • Tunneling (actually a consequence of the point-mass assumption)

  • Rapid nuclear movements reduce accuracy

  • Large changes in electronic structure caused by small changes in nuclear position reduce accuracy


Whither nanotechnology

Buckyballs


Whither nanotechnology

Buckytubes

Fullerenes

SWNT

MWNT

Chirality

Buckminsterfullerenes


Whither nanotechnology

Buckytubes

What is “chirality?”


Whither nanotechnology

Molecular

constructor

Molecular

constructor

Molecular

constructor

Broadcast architecture

Macroscopic

computer

http://www.zyvex.com/nanotech/selfRep.html


Nanopores

Nanopores

Illustration from Harvard Nanopore Group


Millipede

Millipede

Illustration from IBM Zurich


Whither nanotechnology

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Whither nanotechnology

System designs

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Whither nanotechnology

System designs

Why don’t we have more system designs?

Development times are 10+ years

Planning horizons are usually 10- years

Research funding focused on “science”

FUD


Whither nanotechnology

What to do

  • Shorten development times

  • Identify intermediate targets

  • Gain support from groups with long planning horizons

  • Lengthen planning horizons

  • Reduce FUD by detailed design and analysis


Whither nanotechnology

Stiffness

E:Young’s modulus

k: transverse stiffness

r: radius

L:length


Whither nanotechnology

Stiffness

E:1012 N/m2

k: 10 N/m

r: 8 nm

L:100 nm


Whither nanotechnology

Convergent assembly


Whither nanotechnology

Convergent assembly


Whither nanotechnology

Convergent assembly


Whither nanotechnology

Space

  • SSTO (Single Stage To Orbit) vehicle

  • 3,000 kg total mass (including fuel)

  • 60 kilogram structural mass

  • 500 kg for four passengers with luggage, air, seating, etc.

  • Liquid oxygen, hydrogen

  • Cost: a few thousand dollars

K. Eric Drexler, Journal of the British Interplanetary Society,

V 45, No 10, pp 401-405 (1992).

Molecular manufacturing for space systems: an overview


An overview of replicating systems for manufacturing

An overview of replicating systemsfor manufacturing

Replication

  • Advanced Automation for Space Missions, edited by Robert Freitas and William Gilbreath NASA Conference Publication 2255, 1982

  • A web page with an overview of replication: http://www.zyvex.com/nanotech/selfRep.html


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