Nanotechnology: basic concepts and potential applications

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Nanotechnologybasic concepts and potential
applications

• Ralph C. Merkle, Ph.D.
• Principal Fellow

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Slides on web

• The overheads (in PowerPoint) are available on
  the web at
• http//www.zyvex.com/nanotech/talks/ppt/
• Berkeley 010505.ppt

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Foresight

• Ninth Foresight Conferenceon Molecular
  Nanotechnology
• November 9-11, 2001
• Santa Clara, CaliforniaIntroductory tutorial
  November 8
• www.foresight.org/Conferences/MNT9/

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Foresight
www.nanodot.org
www.foresight.org/SrAssoc/
Gatherings
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Health, wealth and atoms
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Arranging atoms

• Diversity
• Precision
• Cost

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Richard Feynman,1959
Theres plenty of room at the bottom
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Eric Drexler, 1992
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President Clinton, 2000
The National Nanotechnology Initiative

• 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.

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Terminology

• The term nanotechnology is very popular.
• Researchers tend to define the term to include
  their own work. Definitions abound.
• A more specific term
• molecular nanotechnology

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Arrangements of atoms
.
Today
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The goal
.
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New technologies

• Consider what has been done, and improve on it.
• Design systems de novo based purely on known
  physical law, then figure out how to make them.

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New technologies
If the target is close to what we can make, the
evolutionary method can be quite effective.
What we can make today (not to scale)
Target
.
.
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New technologies
Molecular Manufacturing
But molecular manufacturing systems are not
close to what we can make today.
What we can make today (not to scale)
.
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Working backwards

• Backward chaining (Eric Drexler)
• Horizon mission methodology (John Anderson)
• Retrosynthetic analysis (Elias J. Corey)
• Shortest path and other search algorithms in
  computer science
• Meet in the middle attacks in cryptography

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Overview
Core molecular manufacturing capabilities
Products
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Today
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Scaling laws

• Length meter mm 0.001
• Area meter2 mm2 0.000001
• Volume meter3 mm3 0.000000001
• Mass kilogram mg 0.000000001
• Time second ms 0.001
• Speed m/s mm/ms 1

Chapter 2 of Nanosystems
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Molecular mechanics

• Manufacturing is about moving atoms
• Molecular mechanics studies the motions of atoms
• Molecular mechanics is based on the
  Born-Oppenheimer approximation

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Born-Oppenheimer

• The carbon nucleus has a mass over 20,000 times
  that of the electron
• Moves slower
• Positional uncertainty smaller

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Quantum uncertainty

• s2 positional variance
• k restoring force
• m mass of particle
• h Plancks constant divided by 2p

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Quantum uncertainty

• C-C spring constant k440 N/m
• Typical C-C bond length 0.154 nm
• s for C in single C-C bond 0.004 nm
• s for electron (same k) 0.051 nm

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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 dont even have to compute the
  electronic structure

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Hydrogen molecule H2
Energy
Internuclear distance
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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

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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

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What to make
Diamond physical properties

• Property Diamonds value Comments
• Chemical reactivity Extremely low
• Hardness (kg/mm2) 9000 CBN 4500 SiC 4000
• Thermal conductivity (W/cm-K) 20 Ag 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) 5.5 Si 1.1 GaAs 1.4
• Resistivity (W-cm) 1016 (natural)
• Density (gm/cm3) 3.51
• Thermal Expansion Coeff (K-1) 0.8 x 10-6 SiO2
  0.5 x 10-6
• Refractive index 2.41 _at_ 590 nm Glass 1.4 - 1.8
• Coeff. of Friction 0.05 (dry) Teflon 0.05
• Source Crystallume

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Hydrocarbon bearing
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Hydrocarbon universal joint
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Rotary to linear
NASA Ames
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Bucky gears
NASA Ames
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Bearing
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Planetary gear
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Neon pump
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Fine motion controller
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Positional assembly
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Stewart platform
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Thermal noise
s mean positional error k restoring force kb
Boltzmanns constant T temperature
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Thermal noise
s 0.02 nm (0.2 Å) k 10 N/m kb 1.38 x 10-23
J/K T 300 K
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Stiffness
E Youngs modulus k transverse stiffness r
radius L length
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Stiffness
E 1012 N/m2 k 10 N/m r 8 nm L 100 nm
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Experimental work
Gimzewski et al.
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Experimental work
H. J. Lee and W. Ho, SCIENCE 286, p. 1719,
NOVEMBER 1999
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Experimental work
Manipulation and bond formation by STM
Saw-Wai Hla et al., Physical Review Letters 85,
2777-2780, September 25 2000
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Buckytubes
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Experimental work
Nadrian Seemans truncated octahedron from DNA
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Pathways
Self assembly of a positional device

• Stiff struts
• Adjustable length

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Sliding struts
ABCABCABCABCABCABCABCABCABCABCABCABC a
a a a
x x x x
XYZXYZXYZXYZXYZXYZXYZXYZXYZXYZXYZXYZ
a x
joins the two struts
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Sliding struts
ABCABCABCABCABCABCABCABCABCABCABCABC a c
a ca c a / / /
xy xy x y x
XYZXYZXYZXYZXYZXYZXYZXYZXYZXYZXYZXYZ
a x
c y
join the two struts
and
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Sliding struts
ABCABCABCABCABCABCABCABCABCABCABCABC c
c c c
y y y y
XYZXYZXYZXYZXYZXYZXYZXYZXYZXYZXYZXYZ
c y
Joins the two struts, which have now moved over
one unit.
Cycling through a-x, c-y and b-z produces
controlled relative motion of the two struts.
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Self replication
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Complexity (bits)

• Von Neumann's constructor 500,000
• Mycoplasma genitalia 1,160,140
• Drexler's assembler 100,000,000
• Human 6,400,000,000
• NASA over 100,000,000,000

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Replication
There are many ways to make a replicating system

• There are nine and sixty ways
• of constructing tribal lays,
• And every single one of them
• is right.
• Rudyard Kipling

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Replication
There are many ways to make a replicating system

• Von Neumann architecture
• Bacterial self replication
• Drexlers original proposal for an assembler
• Simplified HydroCarbon (HC) assembler
• Exponential assembly
• Convergent assembly
• And many more

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Self replication
A C program that prints outan exact copy of
itself

• main()char q34, n10,a"main() char
  q34,n10,acscprintf(a,q,a,q,n)c"printf(
  a,q,a,q,n)

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Self replication
English translation

• Print the following statement twice, the second
  time in quotes
• Print the following statement twice, the second
  time in quotes

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Self replication
The Von Neumann architecture
Universal Computer
Universal Constructor
http//www.zyvex.com/nanotech/vonNeumann.html
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Elements in Von Neumann Architecture
Self replication

• On-board instructions
• Manufacturing element
• Environment
• Follow the instructions to make a new
  manufacturing element
• Copy the instructions

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Self replication
The Von Neumann architecture
Instructions
New manufacturing element
Manufacturing element
http//www.zyvex.com/nanotech/vonNeumann.html
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Self replication
The Von Neumann architecture
Read head
Instructions (tape)
New manufacturing element
Manufacturing element
http//www.zyvex.com/nanotech/vonNeumann.html
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Self replication
Replicating bacterium
DNA
DNA Polymerase
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Self replication
Drexlers proposal for an assembler
http//www.foresight.org/UTF/Unbound_LBW/chapt_6.h
tml
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Broadcast architecture
Macroscopic computer
http//www.zyvex.com/nanotech/selfRep.html
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Broadcast architecture
Some broadcast methods Pressure
(acoustic) Electromagnetic (light,
radio) Chemical diffusion Electrical
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Acoustic broadcast

• Can provide both power and control
• Multi-megahertz operation
• Moderate pressure (DP one atmosphere) can be
  reliably detected with small pressure actuated
  pistons
• Feasible designs

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Pressure actuated device
External gas
Actuator (under tension)
Compressed gas
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Piston design issues

• External pistons to detect pressure changes
• Two pistons can drive a demultiplexor, which in
  turn drives tens of signal lines
• Polyyne (carbyne) rods in buckytube sheaths is
  adequate to convey force (derailleur cable
  mechanism)

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Piston design issues

• 12 nm radius by 20 nm length for a volume of
  about 9,000 nm3
• 105 Pa ( one atmosphere) results in DP DV
  10-18 Joules 200 kT at room temperature (high
  reliability)
• Force of 45 piconewtons

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Advantages of broadcast architecture
Broadcast replication

• Smaller and simpler no instruction storage,
  simplified instruction decode
• Easily redirected to manufacture valuable
  products
• Inherently safe

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HC assembler
Approximate dimensions 1,000 nm length 100 nm
radius
Compressed neon
http//www.zyvex.com/nanotech/casing.html
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Elements in HC assembler
Broadcast replication

• No on-board instructions (acoustic broadcast)
• No on-board computer
• Molecular positional device (robotic arm)
• Liquid environment solvent and three feedstock
  molecules
• Able to synthesize most stiff hydrocarbons
  (diamond, graphite, buckytubes, etc)

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Buckytubes as casings

• Well studied, robust
• Warning synthesis of this casing will not use
  anything resembling current methods. Bucky tubes
  are well understood and well studied, simplifying
  design.

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Replication

• An assembler manufactures two new assemblers
  inside its casing
• The casings of the new assemblers are rolled up
  during manufacture
• The original assembler releases the new
  assemblers by releasing the casing from the
  manufacturing component

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Casing shape

• Compressed neon to maintain shape
• Pressure too low results in collapse
• Pressure too high bursts casing
• Pressures in the range of several tens of
  atmospheres should work quite well

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Feedstock

• Acetone (solvent)
• Butadiyne (C4H2, diacetylene source of carbon
  and hydrogen)
• Neon (inert, provides internal pressure)
• Vitamin (transition metal catalyst such as
  platinum silicon tin)

http//nano.xerox.com/nanotech/hydroCarbonMetaboli
sm.html
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Parts closure

• A set of synthetic pathways that permits
  construction of all molecular tools from the
  feedstock.
• Cant go downhill, must be able to make a new
  complete set of molecular tools while preserving
  the original set.
• http//www.zyvex.com/nanotech/
• hydroCarbonMetabolism.html
• (about two dozen reactions)

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Binding sites
HC assembler
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HC assembler
Freitas, adapted from Drexler
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HC assembler
Freitas, adapted from Drexler
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Subsystems
HC assembler

• Casing
• Binding sites (3)
• Pistons (2)
• Demultiplexor
• Positional device
• Tool synthesis
• Zero residue

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Design and modeling of HC assembler feasible today
Assembler design project

• Speed development
• Explore alternative designs
• Clearer target
• Clearer picture of capabilities

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Making diamond today
Illustration courtesy of P1 Diamond Inc.
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A synthetic strategy for the synthesis of
diamondoid structures
Molecular tools

• Positional assembly (6 degrees of freedom)
• Highly reactive compounds (radicals, carbenes,
  etc)
• Inert environment (vacuum, noble gas) to
  eliminate side reactions

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Hydrogen abstraction tool
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Other molecular tools
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C2 deposition
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Carbene insertion
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Micro rotation
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Exponential assembly
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Exponential assembly

• No on-board instructions (electronic broadcast)
• External X, Y and Z (mechanical broadcast)
• No on-board computer
• MEMS positional device (2 DOF robotic arm)
• Able to assemble appropriate lithographically
  manufactured parts pre-positioned on a surface in
  air

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Convergent assembly
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Convergent assembly
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Convergent assembly
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Convergent assembly
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Replication
Take home message the diversity of replicating
systems is enormous

• Functionality can be moved from the replicating
  component to the environment
• On-board / off board instructions and computation
• Positional assembly at different size scales
• Very few systematic investigations of the wide
  diversity of replicating systems

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Replication
Take home message and manufacturing costs will
be very low

• Potatoes, lumber, wheat and other agricultural
  products have costs of roughly a dollar per
  pound.
• Molecular manufacturing will make almost any
  product for a dollar per pound or less,
  independent of complexity. (Design costs,
  licensing costs, etc. not included)

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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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Replication
Popular misconceptionsreplicating systems must

• be like living systems
• be adaptable (survive in natural environment)
• be very complex
• have on-board instructions
• be self sufficient (uses only very simple parts)

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Replication
Misconceptions are harmful

• Fear of self replicating systems is based largely
  on misconceptions
• Misplaced fear could block research
• And prevent a deeper understanding of systems
  that might pose serious concerns
• Foresight Guidelines address the safety issues

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Replication
What is needed

• Development and analysis of more replicating
  architectures
• Systematic study of existing proposals
• Education of the scientific community and the
  general public

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Impact
The impact of a new manufacturing
technology depends on what you make
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Impact
Powerful Computers

• Well 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

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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, ...

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Impact
Nanomedicine

• Disease and ill health are caused largely by
  damage at the molecular and cellular level
• Todays surgical tools are huge and imprecise in
  comparison

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Impact
Nanomedicine

• In the future, we will have fleets of surgical
  tools that are molecular both in size and
  precision.
• We will also have computers much smaller than a
  single cell to guide those tools.

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Impact
Size of a robotic arm 100 nanometers
8-bit computer
Mitochondrion 1-2 by 0.1-0.5 microns
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Impact
Mitochondrion
Size of a robotic arm 100 nanometers
Typical cell 20 microns
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Typical cell
Mitochondrion
Molecular computer peripherals
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Remove infections
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Clear obstructions
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Respirocytes
http//www.foresight.org/Nanomedicine/Respirocytes
.html
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Release/absorb

• ATP, other metabolites
• Na, K, Cl-, Ca, other ions
• Neurotransmitters, hormones, signaling molecules
• Antibodies, immune system modulators
• Medications
• etc.

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Correcting DNA
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Nanomedicine Volume I

• Nanosensors, nanoscale scanning
• Power (fuel cells, other methods)
• Communication
• Navigation (location within the body)
• Manipulation and locomotion
• Computation
• http//www.foresight.org/Nanomedicine

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A revolution in medicine

• Today, loss of cell function results in cellular
  deterioration
• function must be preserved
• With medical nanodevices, passive structures can
  be repaired structure must be preserved

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Cryonics
Liquid nitrogen
Temperature
Time
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Clinical trials

• Select N subjects
• Vitrify them
• Wait 100 years
• See if the medical technology of 2100 can indeed
  revive them
• But what do we tell those who dont expect to
  live long enough to see the results?

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Payoff matrix



It works
It doesn't

Experimental group www.alcor.org
A very long and healthy life
Die, lose life insurance





Control group
Die
Die


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Public perception

• Thus, like so much else in medicine, cryonics,
  once considered on the outer edge, is moving
  rapidly closer to reality
• ABC News World News Tonight, Feb 8th
• medical advances are giving new credibility
  to cryonics.
• KRON 4 News, NightBeat, May 3, 2001

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Shirley MacLaine

• Everyone who has died and told me about it has
  said its terrific!

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Space

• Launch vehicle structural mass could be reduced
  by about a factor of 50
• Cost per pound for that structural mass can be
  under a dollar
• Which will reduce the cost to low earth orbit by
  a factor of better than 1,000

http//science.nas.nasa.gov/Groups/ Nanotechnology
/publications/1997/ applications/
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Space

• Light weight computers and sensors will reduce
  total payload mass for the same functionality
• Recycling of waste will reduce payload mass,
  particularly for long flights and permanent
  facilities (space stations, colonies)

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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
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Space

• Solar electric ion drive
• Thin (tens of nm) aluminum reflectors concentrate
  light
• Arrays of small ion thrusters
• 250,000 m/s exhaust velocity
• Acceleration of 0.8 m/s
• Tour the solar system in a few months

K. Eric Drexler, Journal of the British
Interplanetary Society, V 45, No 10, pp 401-405
(1992). Molecular manufacturing for space
systems an overview
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Space

• ONeill Colonies
• Dyson spheres
• Skyhooks
• Max population of solar system

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Weapons

• 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//nano.xerox.com/nanotech/nano4/jeremiahPaper
.html
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Weapons
Gray goo, gray dust,

• New technologies, new weapons
• At least one decade and possibly a few decades
  away
• Public debate has begun
• Research into defensive systems is essential

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Human impacton the environment
The environment

• Population
• Living standards
• Technology

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Reducing human impacton the environment
The environment

• Greenhouse agriculture/hydroponics
• Solar power
• Pollution free manufacturing

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How long?

• The scientifically correct answer is I
  dont know
• Trends in computer hardware suggest early in this
  century perhaps in the 2010 to 2020 time frame
• Of course, how long it takes depends on what we do

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• Nanotechnology offers ... possibilities for
  health, wealth, and capabilities beyond most past
  imaginings.
• K. Eric Drexler

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Arranging Molecular Building Blocks (MBBs) with
SPMs
Positional assembly

• Picking up, moving, and putting down a molecule
  has only recently been accomplished
• Stacking MBBs with an SPM has yet to be done

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Designing MBBs and SPM tips
Positional assembly

• The next step is to design an MBB/SPM tip
  combination that lets us pick up, move, put down,
  stack and unstack the MBBs
• A wide range of candidate MBBs are possible

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Energy

• The sunshine reaching the earth has almost 40,000
  times more power than total world usage.
• Molecular manufacturing will produce efficient,
  rugged solar cells and batteries at low cost.
• Power costs will drop dramatically

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Mitochondrion
Molecular bearing
20 nm scale bar
Ribosome
Molecular computer (4-bit) peripherals