Mechanical Applications of Nanotechnology

1. Mechanical Applications of Nanotechnology Jaynesh Shah Greg Pudewell Edwin L. Youmsi Pete John Pack

2. Overview Introduction Single-Molecule Optomechanical Cycle A Crossover in the Mechanical Response ofNano-crystalline CeramicsPaper 3 Strong Coupling Between Single-Electron Tunneling and Nanomechanical Motion Impact Further Research Conclusion

3. Introduction http://www.nsf.gov/ • Mechanical engineering at nanometer scales is becoming important • National Science Foundation two-day workshop • Areas of greatest contributions • Engineering education • Multidisciplinary field • Atomic-level effects www.sciencespot.net/Pages/kdzchem.html

4. Challenges http://www.grc.nasa.gov/WWW/K-12/airplane/state.html • Change in Physical Properties • Solids, Liquids, and gases confined to regions smaller than 100 nm • Affected Properties • Thermal Conductivity • Electrical Conductivity • Optical Absorption • Emission Spectra • Mechanical Strength • Viscosity

5. Vision http://www.pdphoto.org/PictureDetail.php?mat=pdef&pg=5667 http://scrapetv.com/News/News%20Pages/Entertainment/pages-2/Cancer-Ecstatic-to-be-free-of-Jade-Goody-Scrape-TV-The-World-on-your-side.html http://green.autoblog.com/2007/06/18/loremo-high-res-gallery-of-live-pics/ • Basis for structures, devices, and systems that could have tremendous impact • Information • Energy • Health • Agriculture • Security • Transportation • 1 terabit per square inch • High efficiency solid-state engines • Analysis of single cells for diagnosis • Ultra Light and Ultra Strong Materials

6. Mechanical Applications http://www.thealarmclock.com/euro/archives/2007/10/from_austria_semicon_1.html http://commons.wikimedia.org/wiki/File:Atomic_force_microscope_block_diagram.png • Instruments • Nano-indentors • Atomic Force Microscopes • Feedback control • Nano-scale precision • Measure forces down to piconewton levels • Integration and Packaging • Integrating building blocks in a rational manner to make a functional device or system • Manufacturing • Assembling large quantities of nanostructures

7. Single-MoleculeOptomechanical Cycle Thorsten Hugel, Nolan B. Holland, Anna Cattani, Luis Moroder, Markus Seitz, Hermann E. Gaub

8. Purpose californiaimage.com Nano-robots and future nano devices need some sort of power source This paper proposes a way to harness power from light on the nano-scale.

9. Theory • (A) Photosensitive azobenzenes lengthen and contract when exposed to light • Occurs due to switch from –cis to –trans • Mechanical work is delivered when a force is applied • (B) Structure of azobenzene

10. Experiment • Experiment to prove that azobenzenes can be manipulated this way • A diagram of the force exerted on a polymer of azobenzene • ΔL = 1.9 nm for monomer • Force applied vs. length for –trans (red) and –cis (blue)

11. Proof of Theory • The experiment showed that it is possible to: • Handle an individual polyazopeptide strand • Measure its length mechanically • Excite the polymer and change it to the desired configuration • Detect the transition mechanically getentrepreneurial.com

12. So What? • Mechanical energy can be obtained in the following steps (theory): • (I) polymer in –trans state • (II) force applied • (III) light changes configuration to –cis • (IV) force removed • (I) light changes polymer back to –trans

13. Experiment • Experimental realization of theory on previous slide: • (I) 420 nm light assures polymer in –trans state at ~100 pN • (II) F = 200 pN • (III) 365 nm light changes configuration to –cis • (IV) F = 100 pN • (I) 420 nm light changes polymer back to –trans

14. Results • It is possible to convert light energy into mechanical energy using azobenzenes • Nano-bots and other nano-devices now have a possible way of being self-sustaining http://i.telegraph.co.uk/telegraph/multimedia/archive/01518/nano-robot_1518042i.jpg

15. Future Research Determine effects of using multiple strands of polyazopeptides Try other types of molecules that can switch between –trans and –cis via lightwaves Determine optimal force to stretch polymer Research other ways to increase efficiency to make this a viable option for nano-robotics

16. A Crossover in theMechanical Response ofNano-crystalline Ceramics by Izabela Szlufarska, Aiichiro Nakano & Priya Vashishta

17. Introduction • The great interest in nano-structured ceramics originates from the observations and expectations of unique mechanical properties in these materials. • Examples in normally brittle ceramics include: • Very high hardness • High fracture toughness • Superplastic behavior • Silicon carbide is of particular interest because of its potential technological applications in high-temperature structural and electronic components. • Although enhanced mechanical properties are often associated with the reduction in grain sizes, it has recently been conjectured that nano-structured ceramics might exhibit an inverse Hall-Petch effect • Hardness decreases when grain size decreases in the nano-scale grain-size regime • Such peculiar behavior has been observed in ductile nano-phase materials (e.g., nano-structured metals) with porous grain boundaries (GBs) by means of simulations and experiments. • The behavior was attributed to a crossover from dislocation-mediated plasticity for large grain size to GB sliding for small grain size. • A similar mechanistic understanding in ceramics is still lacking.

18. Introduction In contrast with nano-structured metals, nano-structured ceramics have an increased volume fraction of disordered intergranular films, which are observed both experimentally and by means of molecular dynamics (MD) simulations. In particular, for brittle ceramics such as SiC, mechanical properties such as toughness are essentially determined by soft (often amorphous) GB phases. Recent experiments of nano-indentation of nano-crystalline SiC (n-SiC) films with grain sizes of 5 to 20 nm have shown “superhardness,” i.e., hardness largely exceeding that of a bulk crystalline SiC (3C-SiC). The experimental hardness was shown to be sensitive to the grain size and the fraction of the amorphous GB phase. However, their effects on mechanical responses at the atomistic level are largely unknown.

19. Introduction The MD simulations consisted of a 625x625x535 Å3 n-SiC substrate containing 18.7 million atoms, which had randomly oriented grains with diameters averaging 8 nm and a density of 2.97 g/cm3 at a temperature of 300 K. Structural ordering in GBs is analyzed by means of a partial pair distribution function g(r), which quantifies the probability of finding two atoms at an interatomic distance r.

20. Figures

21. Results and Discussion To shed light on the atomistic mechanisms underlying mechanical response of n-SiC, the researchers indented the substrate with a square-base indenter of size 160x160x72 Å3. Nano-indentation is a unique local probe to measure mechanical properties of materials. Even though experimental indenters are round on this scale, a square-base indenter helps to maximize the applied stress and the localized plastic flow in the material on length and time scales available to simulations.

22. Results and Discussion Regime 1 is entirely elastic and ends at h = 7.5 Å. Regime 2 extends up to the crossover depth hCR ~ 14.5 Å and is characterized by a very small hysteresis during unloading as compared with a much more pronounced plastic yield at hCR. The small plastic flow is related to the non-equilibrium structure of the amorphous interfaces, which can relax within a short migration distance. A similar effect has been observed during MD simulations of bulk a-SiC. Because up to hCR the amorphous “cementlike” GBs hold the grains together, regimes 1 and 2 are characterized by cooperative continuous intergranular response. The cooperative motion of grains is identified by analyzing atomic displacements. It involves both formation of mesoscopic shear planes involving several grains and coupling to grains outside of the area directly beneath the indenter to form an extended elastic zone. Formation of mesoscopic shear planes has been previously observed in MD simulations of nano-crystalline Ni.

23. Results and Discussion Regime 3 starts when amorphous GBs yield plastically at hCR ~ 14.5 Å and henceforth grains are effectively decoupled from one another. The substrate contains a small number of nano-pores, which collapse under the indenter, thereby reducing the yield stress. In experimental nano-ceramics, the volume fraction of pores can be as high as 20%. The crystalline phase within the grains does not yield until the onset of regime 4 at h = 18.5 Å. This response is distinct from that of nano-structured metals, in which a dislocation within the grain is nucleated at the onset of substrate yielding. Discrete plastic events, such as a dislocation glide, take place within the grains in close proximity to the indenter and are reflected in the rougher character of the P-h curve. Similar periodic load drops have been observed for the nano-indentation in bulk 3C-SiC. In the case of n-SiC, the load drops are much less pronounced than in 3C-SiC, because the calculated load is averaged over a few grains covered by the indenter and the discrete events in a grain are decoupled from those in the neighboring grains.

24. Figures

25. Figures

26. Results and Discussion The crossover and localization of deformation are also manifested in the rotation of grains.

27. Figures

28. Results and Discussion The observed crossover is correlated to a competition between crystallization and disordering in the substrate. To study this effect, the researchers analyzed topological disorders based on the analysis of rings, where a ring is defined as the shortest closed path of alternating Si-C atomic bonds. Each atom in a perfect 3C-SiC has 12 unique threefold rings (these are ordered atoms), and a topological disorder is reflected in the presence of rings that are not threefold (disordered atoms).

29. Figures

30. G. A. Steele,* A. K. Hüttel,† B. Witkamp, M. Poot, H. B. Meerwaldt, L. P. Kouwenhoven, H. S. J. van der Zant Strong Coupling BetweenSingle-Electron Tunneling andNanomechanical Motion

31. High frequency nanoscale resonators Many measurement applications: Spectral sensing Nanoscale transducers PlasmonicPhotodetection Ultrasensitive mass detection Background http://www.core.org.cn/OcwWeb/Materials-Science-and-Engineering/3-052Spring-2007/CourseHome/index.htm

32. High-quality mechanical resonator Driven into motion by radio frequency potential Periodic modulations of the mechanical resonance frequency Background http://media.audiojunkies.com/radio-tower.jpg&imgrefurl=http://www.audiojunkies.com/blog/644/radio-frequency-interference-from-nearby-am-radio-station-tower&usg

33. Prior Related Studies • Pioneering approaches: • Aluminum single-electron transistors used as position detectors • Atomic force microscopy cantilevers as resonators http://people.bath.ac.uk/pyssc/pics/array.JPG

34. High-Q nanotube mechanical resonator Nanotube suspended across a trench that makes electrical contact to two metal electrodes Measurements at 20 mK with an electron temperature of ~80 mK Procedure http://www.scienceonline.org/cgi/content/full/325/5944/1103

35. Coulomb oscillations Detection current vs, frequency Asymmetric line shape Sharp subpeaks and several jumps in amplitude Large RF driving force and small Vsd Mechanical Resonance http://www.scienceonline.org/cgi/content/full/325/5944/1103

36. Mechanical resonance by single-electron tunneling Differential conductance Ridges of sharp positive (red) and negative (blue) Small RF driving force and large Vsd Mechanical resonance http://www.scienceonline.org/cgi/content/full/325/5944/1103

37. Direct current through the nanotube spontaneously drives the mechanical resonator Exerts a force that is coherent with the high-frequency resonant mechanical motion Results http://www.google.com/imgres?imgurl=http://ysm.research.yale.edu/images/79.4/595.jpg&imgrefurl

38. Single-electron tuning oscillations are a mechanical that is a direct consequence of single-electron tunneling oscillations Results http://prattpress.pratt.duke.edu/files/prattpress/oscillation_main.jpg

39. Study effects at varying Q values Effects of instability when tunnel rate is below mechanical resonance frequency Suggestions for Further Research http://images.machinedesign.com/images/archive/molec0400jpg_00000031955.jpg

40. Conclusions and Future Research • The researchers’ estimate of n-SiC hardness (defined as maximum load divided by the cross-sectional area of the indenter) of 39 GPa is in agreement with experimental value of “superhardness” of 30 to 50 GPa for grain sizes of 5 to 20 nm. • These experimental measurements are sensitive to the grain size and to the fraction of amorphous intergranular phase. • This indicates an essential role of the interplay between discrete (crystalline) intragranular and continuous (amorphous) intergranular responses as a function of the length scale in determining mechanical properties • Some particularly promising potential applications are in • Advanced superhard nano-structured coatings • High-speed machining and tooling • Potential materials for bio-implants • The two-phase character of nano-structured ceramics results in a crossover between the two aforementioned responses, and this crossover sheds light on the competition between different deformation mechanisms underlying design and fabrication of nano-structured ceramics with enhanced mechanical properties.

41. Conclusions • Mechanical applications of nanotechnology are upcoming and necessary for further development. • Nano-devices need a power source • Power harnessed from light • Physical properties are dependent on grain size, and nano-identation is a unique way to measure a material’s physical properties • Nanoscale mechanical resonance are very useful for measurements • Spectral sensing • Nanoscale transducers • PlasmonicPhotodetection • Ultrasensitive mass detection

42. Impact • Researchers • Light at the end of the tunnel • Out of theory stage • Increased funding • Future consumers • Reliable products

44. U5 Second Presentation Rebuttal • Many critiques were about keeping the slides consistent. This is very important in maintaining coherency through a presentation and will be improved accordingly • There were critiques about some slides (specifically the 2nd paper) containing too much text. It is difficult to be concise on a complicated paper, but this is something that should be worked on • Additionally, reading off the slides should not be done either, as some groups mentioned • There seemed to be some disagreement on how effective our conclusion was. We will work on making the conclusion less open-ended, so that all the objectives are covered. • Most groups liked the professionalism of our attire • We should have practiced more beforehand to make the presentation more seamless • All comments are greatly appreciated and it only makes us better presenters

45. Evaluation of U5 Presentation:Mechanical Applications of Nanotechnology U1 John DeLeonardis Bob Deborde Kamal Banjara Rodrigo Benedetti

46. Positive Aspects • Good organization • Consistent format between papers • Logical • Use of several papers • Most slides had a picture or graphic • Slides looked good overall http://i.telegraph.co.uk/telegraph/multimedia/archive/01518/nano-robot_1518042i.jpg

47. Suggestions for improvement • Several slides contained no pictures • Several slides for the second paper contain too much text • use phrases in bullets, not full sentences • Include a few slides at the end to tie the whole presentation together instead of ending abruptly after your last paper http://www.google.com/imgres?imgurl=http://ysm.research.yale.edu/images/79.4/595.jpg&imgrefurl

48. Review of Group U5’s Presentation- Mechanical Applications Of Nanotechnology By Group U2: -Kyle Demel -Keaton Hamm -Bryan Holekamp -Rachael Houk http://www.nanotech-now.com/news_images/36216.jpg

49. Improvements for slides: • Slide Formatting – The group needs to do a better job of merging all the slide into a professionally looking presentation. The PowerPoint posted on the website should just be a rough draft. The text size varies between each slide, which looks very unprofessional. Some of the slides had text that was hardly legible from the second row, and other slides had text that was too large for the back of the room. The group needs to do a better job of consistency. Some slides had paragraphs of explanatory material. Other slides had a few brief sentences and a picture. A good PowerPoint slide will have about 3 to 5 brief bullet points and several good graphics. Some slides were good, but most had too much information. • Figures – The group needs to incorporate more figures and on every slide. With the exception of the first and third article, the figures were too small and needed to be enlarged. Adding appropriately sized pictures would greatly improves the appearance of the slides. • Wasted space – The slides appeared to contain a large amount of wasted space with only half of each slide being devoted to containing inform- ation. Space the text out more if you have to, but do not leave half a slide blank without reason. http://www.kirainet.com/images/nanobot.jpg

50. Improvements for presentation: • Background – The background was very brief, and predictably, not very informative. The speakers rushed through the introduction in about two or three minutes. More time should be committed to communicating the basic material. • Graphics – The presentation had a few really neat pictures, but no explanation was provided for these pictures. Please discuss all the graphics that are incorporated into the presentation. If this is an artist’s rendition of a futuristic application, then please say so. Explain the picture and the technology demonstrated in the picture. • Reading Slides – It appeared that some group members were reading off the slides for the majority of their speaking part. Not only does this make for boring presentation, but this habit also makes the speaker look like he does not fully understand the material. Please limit the amount of words that you post on a slide to decrease the temptation to just read the slides. You also should focus more on incorporating audience participation. Practice your speech and look for ways to engage the audience to give a better presentation. • Future Applications – Not much emphasis was added to this topic. Please include more information pertaining to your thoughts, concerns, and wishes for future applications of this technology. http://geekapolis.fooyoh.com/geekapolis_gadgets_wishlist/files/attach/images/1097/559/272/004/robots1.jpg