Presentation on theme: "Mechanical Applications of Nanotechnology Jaynesh Shah Greg Pudewell Edwin L. Youmsi Pete John Pack."— Presentation transcript:
Mechanical Applications of Nanotechnology Jaynesh Shah Greg Pudewell Edwin L. Youmsi Pete John Pack
Overview Introduction Single-Molecule Optomechanical Cycle A Crossover in the Mechanical Response of Nano-crystalline Ceramics A Crossover in the Mechanical Response of Nano-crystalline CeramicsPaper 3 Strong Coupling Between Single-Electron Tunneling and Nanomechanical Motion Impact Further Research Conclusion
Introduction 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
Challenges 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
Vision 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 ment/pages-2/Cancer-Ecstatic-to-be-free-of-Jade- Goody-Scrape-TV-The-World-on-your-side.html res-gallery-of-live-pics/ pdef&pg=5667
Mechanical Applications 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 ile:Atomic_force_microscope_block_ diagram.png rchives/2007/10/from_austria_semico n_1.html
Single-Molecule Optomechanical Cycle Thorsten Hugel, Nolan B. Holland, Anna Cattani, Luis Moroder, Markus Seitz, Hermann E. Gaub
Purpose 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. californiaimage.com
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
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)
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
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
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
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 8/nano-robot_ i.jpg
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
A Crossover in the Mechanical Response of Nano-crystalline Ceramics by Izabela Szlufarska, Aiichiro Nakano & Priya Vashishta
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.
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.
Introduction The MD simulations consisted of a 625x625x535 Å 3 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/cm 3 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.
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 Å 3. 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.
Results and Discussion Regime 1 is entirely elastic and ends at h = 7.5 Å. Regime 2 extends up to the crossover depth h CR ~ 14.5 Å and is characterized by a very small hysteresis during unloading as compared with a much more pronounced plastic yield at h CR. 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 h CR 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.
Results and Discussion Regime 3 starts when amorphous GBs yield plastically at h CR ~ 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.
Results and Discussion The crossover and localization of deformation are also manifested in the rotation of grains.
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).
Strong Coupling Between Single-Electron Tunneling and Nanomechanical Motion G. A. Steele,* A. K. Hüttel,† B. Witkamp, M. Poot, H. B. Meerwaldt, L. P. Kouwenhoven, H. S. J. van der Zant
Background High frequency nanoscale resonators Many measurement applications: – Spectral sensing – Nanoscale transducers – Plasmonic Photodetection – Ultrasensitive mass detection 2007/CourseHome/index.htm
Background High-quality mechanical resonator Driven into motion by radio frequency potential Periodic modulations of the mechanical resonance frequency tower.jpg&imgrefurl=http://www.audiojunkies.com/blog/644/radio-frequency- interference-from-nearby-am-radio-station-tower&usg
Prior Related Studies Pioneering approaches: – Aluminum single-electron transistors used as position detectors – Atomic force microscopy cantilevers as resonators
Procedure 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
Mechanical Resonance Coulomb oscillations – Detection current vs, frequency – Asymmetric line shape – Sharp subpeaks and several jumps in amplitude Large RF driving force and small V sd
Mechanical resonance Mechanical resonance by single-electron tunneling – Differential conductance – Ridges of sharp positive (red) and negative (blue) Small RF driving force and large V sd
Results Direct current through the nanotube spontaneously drives the mechanical resonator Exerts a force that is coherent with the high-frequency resonant mechanical motion 595.jpg&imgrefurl
Results Single-electron tuning oscillations are a mechanical that is a direct consequence of single-electron tunneling oscillations
Suggestions for Further Research Suggestions for Further Research Study effects at varying Q values Effects of instability when tunnel rate is below mechanical resonance frequency
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.
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 – Plasmonic Photodetection – Ultrasensitive mass detection
Impact Researchers – Light at the end of the tunnel – Out of theory stage – Increased funding Future consumers – Reliable products
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 2 nd 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
U1 John DeLeonardis Bob Deborde Kamal Banjara Rodrigo Benedetti Evaluation of U5 Presentation: Mechanical Applications of Nanotechnology
Positive Aspects Good organization Consistent format between papers Logical Use of several papers Most slides had a picture or graphic Slides looked good overall /archive/01518/nano-robot_ i.jpg
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 u/images/79.4/595.jpg&imgrefurl
By Group U2: -Kyle Demel -Kyle Demel -Keaton Hamm -Keaton Hamm -Bryan Holekamp -Bryan Holekamp -Rachael Houk -Rachael Houk Review of Group U5’s Presentation-
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.
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.
Mechanical Applications of Nanotechnology: U5 Review By Group 3: Krista Melish, Phillip Keller, Micheal Jones, James K.
Technical Evaluation Improvements: ▫More informative introduction ▫More pictures and figures, less text Things Done Well: ▫Great color scheme: Easy to read ▫Good choice of relative, interesting papers
Oral Presentation Improvements: ▫Less reading from notes ▫More eye contact Things Done Well: ▫No use of filler words ▫Dressed very professionally ▫Very knowledgeable on the topic ▫Showed confidence
U4 review of U5’s 2 nd presentation U4 Derek Brett Amanda Aziz
Oral Presentation/Slides Slides – The Slide quality was very good, up until the 2 nd paper. It had far too much text and barely any figures. Oral Presentation – All speakers seemed like they didn’t practice quite enough for this presentation. Their voice level and clarity were there but seemed to be lacking the confidence of what they were talking about – Also seemed that they were reading off slides a bit
Technical The introduction was very broad and lacked a specific introduction into the paper. It did a good job introducing the subject but lacked details regarding the research. The papers chosen were very good. The 2 nd paper seemed very confusing, we think spending more time on it and maybe just doing 2 papers would have been better.
Mechanical Applications of Nanotechnology Presented by: Group U5 Critiqued by: Group U6 Pavitra Timbalia & Michael Trevathan
Critique: Oral Presentation & Slides Slide Background made the font easy to read and the pictures easy to see The “Overview” slide let the audience know what to expect We liked how the names of the papers were given on the section header slides The graphics quality varied greatly throughout the presentation ▫Adequate number of slides in the introduction section – they were well cited ▫There were graphics on almost every slide for the 1 st paper ▫The slides for the second paper had too much text (looked very messy) and not enough pictures – the pictures had no captions or citations ▫The slides for the third paper had a good balance of text and pictures Like the way the slides ended –an overall conclusion slide to tied things together really well The presenters mostly did not keep eye contact The first speaker spoke facing the computer screen The third speaker just read the text off of the slides – we could read them too! We felt that the group did not practice at all, this would have helped them greatly make the presentation better Presenters were dressed in business clothes – looked professional study.com/images/oth er-helpful- articles/making-an- oral-presentation- speaking.gif
Critique – Technical Content Introduction was a bit too short ▫It gave a good overview of various mechanical applications ▫Would have liked more background information Choice of research papers seemed relevant to topic discussed ▫Three papers discussed which gave a good range of information on current research ▫Information on the 1 st and 3 rd papers was very concise and showed the results well ▫The second paper was very confusing the way it was presented – summarizing would have helped make it more understandable ▫Each of the papers covered recent research in the field The motivation for each paper given at the beginning - something we really liked Further research was incorporated at the end of the slides for each paper – would have liked to see the impact of this research in the future The conclusions slide was very good as it tied the whole presentation together – what can we expect in the next ten years from this field? Would current method be replaced or supplemented with nanomechanics? We feel that there should have been a “Works Cited” slide at the end of the presentation