Nanotechnology: basic concepts and potential applications

2. Nanotechnology:basic concepts and potential applications Ralph C. Merkle, Ph.D. Principal Fellow

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

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

5. Foresight www.nanodot.org www.foresight.org/SrAssoc/ Gatherings

6. Health, wealth and atoms

7. Arranging atoms • Diversity • Precision • Cost

8. Richard Feynman,1959 There’s plenty of room at the bottom

9. Eric Drexler, 1992

10. 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

11. 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”

12. Arrangements of atoms . Today

13. The goal .

14. 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.

15. 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 . .

16. 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) .

17. 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

18. 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

19. 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

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

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

22. Quantum uncertainty σ2: positional variance k: restoring force m: mass of particle ħ: Planck’s constant divided by 2π

23. 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

24. 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

25. Hydrogen molecule: H2 Energy Internuclear distance

26. 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

27. 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

28. What to make Diamond physical properties Property Diamond’s 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 @ 590 nm Glass: 1.4 - 1.8 Coeff. of Friction 0.05 (dry) Teflon: 0.05 Source: Crystallume

29. Hydrocarbon bearing

30. Hydrocarbon universal joint

31. Rotary to linear NASA Ames

32. Bucky gears NASA Ames

33. Bearing

34. Planetary gear

35. Neon pump

36. Fine motion controller

37. Positional assembly

38. Stewart platform

39. Thermal noise σ: mean positional error k: restoring force kb: Boltzmann’s constant T: temperature

40. Thermal noise σ: 0.02 nm (0.2 Å) k: 10 N/m kb: 1.38 x 10-23 J/K T: 300 K

41. Stiffness E: Young’s modulus k: transverse stiffness r: radius L: length

42. Stiffness E: 1012 N/m2 k: 10 N/m r: 8 nm L: 100 nm

43. Experimental work Gimzewski et al.

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

45. I I Experimental work Manipulation and bond formation by STM Saw-Wai Hla et al., Physical Review Letters 85, 2777-2780, September 25 2000

46. Buckytubes

47. Experimental work Nadrian Seeman’s truncated octahedron from DNA

48. Pathways Self assembly of a positional device • Stiff struts • Adjustable length

49. Sliding struts ABCABCABCABCABCABCABCABCABCABCABCABC a a a a | | | | x x x x XYZXYZXYZXYZXYZXYZXYZXYZXYZXYZXYZXYZ a | x joins the two struts

50. Sliding struts ABCABCABCABCABCABCABCABCABCABCABCABC a c a ca c a |/ |/ | / | xy xy x y x XYZXYZXYZXYZXYZXYZXYZXYZXYZXYZXYZXYZ a | x c | y and join the two struts