Nanotechnology: BIG Ideas From Small Things

1. Nanotechnology:BIG Ideas From Small Things Mike Davis – Harold Washington College RET Director: Northwestern University

2. Outline • Brief Overview of Size and Scale • Making Nanoparticles • Arranging Nanoparticles • Lithography • Nanotechnology in Education • Nanostructures – Gallery

3. Nanotechnology - Basics • Techniques that produce, manipulate or arrange particles that are less than 100nm in their largest dimension. • One nanometer is 1 billionth of a meter. • ‘1 nanometer is the length a man’s beard grows when he picks up the razor’

4. Nano Buzz

5. Nanotechnology – Surface Particles • Individual atoms can exhibit quantum effects. • Groups of atoms can start to exhibit collective effects, but are too big to have noticeable quantum effects. • As particles get bigger, the number of particles on the surface relative to the particles in the interior gets smaller. • Nanotechnology happens when the number of particles on the surface is similar to the number of particles in the bulk.

6. Nanotechnology – Total number of Particles

7. Nanotechnology – More than a size

8. Nanotech - Computing • Moore’s Law • Doubling the number of transistors on an integrated circuit every two years. • Enormous increase in computing power and memory.

9. iPod Nano

10. Demonstration • Bulk properties – Liquid Phase Reaction • Surface Properties – Gas Phase Reaction

11. Gold Nano Particles As these particles get larger, their color becomes more blue in appearance.

12. Making Gold Nanoparticles • Chemical Reaction • Solvated form of the metal (gold or silver) • Introduction of a reducing agent (citrate or borohydride) • Slightly elevated temperature • Control over particle size (monodispersion) • Light conditions • Temperature conditions • Stabilizing media

13. Carbon Nanotubes • Made by passing an electrical arc between two graphite rods. • Seeded by small amounts of metal. • Can be grown to specific lengths, diameters, and wall thickness. • Stronger than steel. • Electrically in some configurations. Semiconductor in other configurations. Chiral in other configurations.

14. Nanoparticle Synthesis – Wet Chemical Chad Mirkin – Northwestern University

15. Nano Printing Press – Micro contact Printing • A technique for modifying surfaces with a high degree of control. • Hydrophobic and hydrophilic regions on a gold surface (CDRs) • Inexpensive method to demonstrate a simple process. • Commonly used technique for surface modification.

16. Nano Printing Press – Microcontact Printing • Expose a gold surface on a CDR. • Pattern the surface with a hydrophilic organic molecule. • Dip the patterned surface in a solution with a hydrophobic organic molecule. • Dry the surface. • Cool the surface below the dew point. • Observe the areas where water condenses.

17. Nano Printing Press • Science is based on a strong bond between gold and sulfur (thiol). • Long organic molecule ends in something either hydrophilic or hydrophobic. • Microcontact printing uses a stamp made by pouring an elastic polymer over a mask. • Finer mask, finer features, more control.

18. Multiple Nano Features with One Mask

19. Micro Contact Printing with Biological Samples - Whitesides

20. Nanoparticle Synthesis – Surfaces Prepare a surface that has a pattern on it. Use those patterns for growing crystals. Teri Odom – Northwestern University

21. Instrumentation – Visualizing the Nanoscale • Most nanofeatures are smaller than the visible wavelengths of light. • Can’t use visible light to determine surface features. • Electron microscopy (wavelength smaller than light) • Force micrscopy (no light used). • Tools of the trade.

22. Scanning Tunneling Microscope • A very sharp tip is brought near a surface. • A voltage is applied between the surface and tip. • Current is measured on the surface to determine the size and shape of features. • STM can resolve features that are 0.1nm wide and 0.01nm high. • Atomic resolution.

23. Atomic Force Microscopy (AFM)

24. Nano-Analogy

25. Nano – Analogy

26. Lithographic Techniques – Solar Photography • Photo sensitive paper • Mixture of iron salts • Place an opaque object over the paper. • Expose the paper to light. • Opaque objects block out the light and expose the rest of the salts. • Exposed iron salts form an insoluble salt. • Unexposed salts are water soluble. • Remove the object. • Wash.

27. Lithographic Techniques in Nanotech • Techniques that build nanostructures or arrays. • Bottom – up approach • Prepare areas on a surface • Utilize self assembly to build up from that point. • Top – down approach • Prepare a surface and etch into it. • Can involve some light based photochemistry.

28. Lithographic Techniques in Nanotech – Top Down Approach • Forming arrays of nanopyramids. • Colloidal crystal of nanospheres on a surface. (Mask) • Thermally deposit metal onto the top of the surface and the sphere mask. • Remove the sphere mask. • Look at the pretty remaining structures. VanDuyne – Nanoletters 2007

29. Colloidal Crystals – Chiang MIT 282 nm 356 nm 424 nm 482 nm

30. Colloidal Crystals – Chiang MIT STM Images of Layers of Polystyrene Spheres on a Silicon substrate. Opals.

31. Nanolithography – Bottom Up Approach • Pattern a surface with something. • Allow other species to assemble there spontaneously. • Grow upwards from the base. • Whitesides – approach to paper based telemedicine.

32. Nano in the Environment • Nanoparticles being made end up being released into the environment. • Unicellular and multicellular organisms pick up the particles. • Silver nanoparticles are antimicrobial. • What are the long term effects of exposure?

33. Nano in Commercial Products • Sunscreen (TiO2 and ZnO) • Silver in bandages. • Silver in plastic food containers. • Nanoscale fabrics on stainresistant clothing. • Carbon nanotubes in sporting equipment. • Particles in stained glass.

34. Nano-Imagination - Robots

35. Nano-Imagination – Robots in the Blood False – Blood Robots True – Nanoparticles to Treat Tumors

36. Nano-Imagination – Reproduction

37. Nano - Resources • NISE-Net: Network of Informal Educators and Researchers (nisenet.org). • MRS Nano Days:Free digital and physical activities for kids and adults. (nisenet.org/nanodays/2010) • National Lab Day: Localized resources for teachers. (Nationallabday.org) • Nanohub: Online resource for computational nanotech (nanohub.org) • iLabcentral: Forum for shared instrumentation. Nanotech coming. (ilabcentral.org)

38. Nano Resources Students - REU • Summer Research Experience for Undergraduates. • Spend the summer working in a lab group. • Potential for a publication. • 8 – 10 weeks. • On campus housing • Stipend ~$4,500 • REU sites all over the US • www.nsec.northwestern.edu/REU • Applications due in Feb.

39. AcknowledgementsKathy CookMargaret Connolly NSF – EEC 0118025 / NSF – EEC 0647560 Questions / Concerns / Comments