G1 Rebuttal: Carbon Nanotube Chirality Edson P. Bellido Sosa.

G1Rebuttal: Carbon Nanotube Chirality

Edson P. Bellido Sosa

Thanks for all your comments, I will try to correct all the mistakes that you point out. I will try to speak slow as many of you suggested.I was the first presenter and I did not have the presentation format, that’s why I did not include further research on my presentation but I will correct this for the next presentation.

Comment: Did not mention some of the major problems with CNT’s.I did not mentioned some of them on the slides but I mentioned about the present manufacturing limitations and purification methods on the talk.

G2Review Controlling carbon nanotube chirality

by Alfredo Bobadilla

Review of “Process to control carbon nanotube chirality”

One option is taking a single (n,m) type SWCNT sample, then cutting those carbon nanotubes to get a higher number of CNTs but smaller ones. Those nanotubes would be used as template to mass produce that particular type of CNT. To grow the CNTs a vapor liquid solid (VLS) amplification growth can be performed. Fe salts can be used to act as the growth catalysts

An additional tool is using NixFe1-x catalytic nanoparticles to changes or control the chirality of the grown CNT.Precise tuning of the nanocatalyst composition at constant size can be achieved by following a gas-phase synthesis route based on an atmospheric-pressure microplasma.The composition-dependent crystal structure of the nanocatalysts determines the carbon nanotube chirality.

Nanotech course – Alfredo Bobadilla

Review:Process to control carbon

nanotubes chirality

By Mary Coan2/9/2010

G3

Review• Overall the presentation was very good• Described – the properties of CNT’s– Methods for obtaining SWCNT’s– Cloning Method

• Did not mention some of the major problems with CNT’s– Today’s manufacturing limitations

• Carbon nanotube network films instead of single CNT’s

– Purification methods for Single walled CNT’s– Formation of complex and entangled bundles

G4Summary ‘Controlling carbon nanotube chirality’

Diego A. Gómez-Gualdrón

Chirality in nanotubes

Geometry-wise a nanotube can be formed by rolling over a graphene sheet to form the nanotube wall

The chirality denotes the amount of twisting in the nanotube (see Fig 1)

Since nanotube properties are chiral-dependant, fine control during production is desired


Approach 1Nanotube ‘cloning’

•A piece of nanotube of given chirality is extracted from a previous process

•Using organic-metallic chemistry catalytic particles are added at both nanotube ends (fig a)

• Growth occurs and chirality is maintained (fig b).

Low number of nanotubes produced


Approach 2Altering nanocatalyst structure

BCC FeFCC Ni

Metals with different structure are alloyed to form a nanoparticle whose structure is concentration-dependant


Approach 2

Panels a,b,c, and d illustrate how the chirality distribution is affected by concentration-dependant changes in the nanoparticle structure


CONCLUSIONS

• Approach 1 is 100% selective but amount produced is minimal and procedure time consuming. (not a good alternative)

• Approach 2 although not 100% effective does show that altering the catalyst structure affects the chirality distribution. It encourages further research, since success would lead to a cost effective process by eliminating post synthesis treatment


Recomendations

• Study the relationship between particular catalyst structures and chirality obtained

• Study how effectively the catalyst structure can be controlled during synthesis


G5Review Controlling carbon nanotube

chirality

by Norma Rangel

CNTs chiralityEdson Bellido

Taken from wikipedia

Good presentationCovered also fabrication and few applicationsI think the material was covered with enough informationHe gave an introduction about the properties, fabrication methods.

Probably something missing was the economic information about the control of CNTs chirality and viability to introduce this methods in industry or high volume fabrication.

Norma Rangel

Process to Control Carbon nanotubes Chirality, by Edson P. Bellido Sosa

• Edson gave a good introduction of CNTs and chirality, including a few interesting methods to separate CNTs with different chiralities such as Selective chemistry: Selective destruction, dielectrophoretic separation, ultracentrifugation and selective growth.

• Some applications of CNTs of different chirality would have complemeted great his presentation.

G6

Review Controlling carbon nanotube chirality by Jung Hwan Woo

Review for Edson’s Presentation

• The electronic properties of CNT is of great interest– metallic CNT is 1000 times more conductive than copper.– MWCNT are superconductive

• What are the problems for electronic applications of CNTs?

• What can a research scientist do to resolve these issues?• Showing an example of the efforts that IBM made (as Dr.

Seminario mentioned) to improve on this aspect.• An additional point to ask is the time needed before a

practically cost-effective CNTs can be produced. This may determine the commercialization of CNTs.

Jung Hwan Woo

G2Rebuttal: Nano electromechanical oscillators

Alfredo Bobadilla

Comment: “Did not describe the theoretical part of the presentation”Answer: The theoretical part was explained during the lecture. In essence, the “beam equation” (classical mechanics) is still useful for analyzing bending-mode vibrations in a carbon nanotube longer than ~0.5um. Research work in the nonlinear regime and the quantum regime has just began very recently.

Comment: “Text was small and hard to locate on each slide”Answer: I’ll improve that next presentation.

Comment: “current or potential applications of such ‘nano’ electromechanical oscillators should have been shown”Answer: The potential applications of nano electromechanical oscillators is shown in the slides and was described during the lecture. It was shown nanotube resonators can be incorporated as the sensing element for improving the performance in mass spectrometry and in calorimetry.

Nano electromechanical oscillators – ‘Rebuttal’

Alfredo D. Bobadilla

G1Electro-Mechanical Oscillators

Review


The presenter describe how a EM oscillator works and the basic equations that rules its movement .He explain how a change in a parameter, lets say the voltage on the system, can affect the overall functioning of the device, and how researcher are taking advantage of these behavior to fabricate consumer devices

He has explained the fabrication process and how a carbon nanotube based oscillator works, and how they can tune the bending mode vibration by changing the gate applied voltage and how they can measure the bending modes using changes in the conductivity of the carbon nanotube

A comparison of the carbon nanotube oscillator and the current oscillator used on the industry, in terms of performance and cost would have been helpful.

Further research is needed specially in the large scale integration process since there is no an high throughput technique to create arrays of carbon nanotube oscillators and other nano-devices.

G3Review: Electromechanical Oscillators

By Mary Coan2/12/2010

Review• Overall the presentation was decent• Described – Current applications of EN oscillators– CNT EM oscillator using various sources and diagrams– Improvements to the performance

• Did not describe the theoretical part of the presentation– Showed many equations with out listing parameters– No physical description of the diagrams

Review

• Overall style of the Presentation was lacking– Text was small and hard to locate on each slide

• Some of these things may have been addressed during the actual presentation. However just looking at the presentation online I had a hard time understanding what each slide represented and the contents of each slide.

G4Summary and review ‘Electromechanical

oscillators’

Diego A Gomez-Gualdron

An electromechanical oscillator circuit

The distance between the plates of the capacitor varies with time, therefore changing the capacitance, which in turn affect the behavior of the circuit giving it an oscillatory behavior

Figure .1

Promising application of a nanotube in a nanocircuit

•A voltage in generates a charge

in

•As a result the nanotube is pushed downwards.

•Bending the nanotube alter the charge once again, ending up in oscillatory motion with a frequency depending on the tension forces in the nanotube.

The oscillatory motion of the nanotube, alterates the capacitance in cyclic-fashion analogous to the macroscale circuit in the fig 1.

Nature 431, 284-287 (16 September 2004) | doi:10.1038/nature02905

Additional Review

• A number of applications were shown for electromechanical oscillators. However, I am not sure if the scale of those examples is in the nanorange. If so, current or potential applications of such ‘nano’ electromechanical oscillators should have been shown.

G5

Review Electromechanical Oscillatorsby Norma Rangel

Electromechanical oscillatorsby Alfredo D. Bobadilla

• Alfredo show the basic concepts of electromechanical oscillators , with examples of how these devices are being implemented in current technologies in the market, alternative applications and a couple of papers about state of the art electromechanical oscillators using nanotubes and origami DNA.

• My suggestion for Alfred presentation is to put more emphasis on the experimental work than being too deep on the theoretical framework

G6

Review Electromechanical Oscillatorsby Jung Hwan Woo

Jung Hwan Woo

Review

• Overall, the presentation needs improvements– Improved presentation skill will help deliver the idea in

a more effective manner– The use of larger fonts and images will make it easier

for the audience to better visualize and understand the concept

– A better introduction may attract the audience into the subject and the presentation.

– The pace can be increased to contain more information. The information on the subject was a bit too little for a 30-minute presentation

Jung Hwan Woo

Application

• What NEMS applications are there, which take advantage of the electromechanical oscillator other than the carbon nanotube application?

• What are the advantage of reducing the size of the device in MEMS/NEMS applications? Is there any downside to it?

G3Rebuttal: Nanosensors Microtubules

Mary Coan

Rebuttal• “An additional interesting point not discussed during the presentation is how

can we exploit the ‘dynamic’ self-assembling properties intrinsic to microtubules for nanosensing and nano-engineering.”– This was not discussed due to time. However it was briefly mentioned that research

into the topic was done but many of the papers found only discussed the targeting the MT’s instead of using the MT’s as nanosensors. For an example, a lot of research has been conducted to inhibit the dynamic instability of MT’s.

• “Nonetheless, it was perhaps too much material for a short time” and “There was a lot of material covered in the slides, perhaps to fast to comprehend in the amount of time given. It became hard to follow at some points.”– You are correct, there was a lot of information presented in a short time. I wanted

the audience to understand the dynamic instability of MT’s, which is one of the most important details about MT’s. Without MT’s mitosis would not occur. I also wanted the audience to fully understand how the MT’s transported nanosensors, which is the first nanotransporter using only biological materials.

– I did limit some of the information presented. This may have caused the audience to become confused or lost at certain points in the presentation.

Rebuttal

• “I could see that the time frames relevant to the technique are quite large, which would create inconveniences for real time measurements and monitoring and quick action expected from point-of-care approaches.”– You are correct. However, I did mention that the authors proposed

removing the separate regions, ie capture and tag regions, to decrease the amount of time needed to detect the analyte. Another point to mention is that the same amount of time, if not more, is required to perform the traditional double-antibody-sandwich (DAS) assays.

• “The graphics and text were well balanced, and the graphics aided a great deal in trying to understand the content of the presentation.”– Thank you. I try to include motion into my presentation to help the

audience.

Rebuttal

• “The speaker covered all relevant topics from an introduction of the research to how it can be furthered. It might have been nice to have heard some of the opposition to such research and or more research in the same field, but overall the presentation was well balanced and informative.”– Thank you, I was struggling to keep the information

too excessive and thus did not include more research in the same field or others points of view

G1

Review Nanosensing, Microtubules by Edson Bellido

The presenter described what are bio-nanosensors and microtubules. She described how the microtubules are formed within the cell. She explained what is the dynamic instability and what molecules affect this behavior of the microtubules. She explained how the microtubules are being used as bio-nanosensor transporter. She explained how the kinase moves the microtubule to the cell boundaries and allow us to detect analytes captured within the cell.

Something missing was the details about the experimental procedures, most likely because of the short time for the presentation. those details are very important factor to analyze and determine the accuracy and reproducibility of the system. Other factor to study will be how the addition of those functionalized MTs and the quantum dots will affect the cellular response. If it affects; quantitatively how this response change the accuracy of the measure?. http://www.cancerquest.org/images/microtubules.gif

G2

Review Nanosensing, Microtubules by Alfredo Bobadilla

Review of Nanosensing & Microtubules

• Microtubules are biological nanostructures. They are part of the cytoskeleton which actually look like the nervous system of the biological cell and they indeed transmit vibrational signals, perform mechanotransduction, own a highly dynamic behavior because of self-assembly dynamic process (dynamic instability) and have been found to be involved in cell decision-process mechanisms as well as in memory & learning functions.

• It was shown in the lecture how functionalized microtubules can be used for nanosensing purposes and as a nanotransporter.

• An additional interesting point not discussed during the presentation is how can we exploit the ‘dynamic’ self-assembling properties intrinsic to microtubules for nanosensing and nano-engineering.


G4Microtubules Summary and review

Diego A Gomez-Gualdrón

Microtubules

•Microtubules (MT) are part of the cytoskeleton and posses a diameter of ~ 25 nm, and a length of ~ 250 nm

•Microtubules (MT) can transmit signals as well as transport substances within the cells

•They are formed by a ‘polymerization mechanism’

Functionalizing a microtubule can make it suitable as a fully-biologically-constitued

nanosensor

Sensing Mechanism

• It was shown that functionalizing a MT with an antibody allows for specific binding of the analyte.

• The interaction of kinesin with the MT enables the transport of the analyte to tagging and detection stages

MT

Detection occurs through fluorescence

Comments

• The presentation used a lot of didactic elements to convey the information and it was general a very good presentation. Nonetheless, it was perhaps too much material for a short time

• I could see that the time frames relevant to the technique are quite large, which would create inconveniences for real time measurements and monitoring and quick action expected from point-of-care approaches.

G5

Review Nanosensing, Microtubules by Norma Rangel

Nanosensors: MicrotubulesBy Mary Coan

• Mary presented the use of microtubules as nanosensors, basic concepts, production of MTs, stability and alternative applications were shown. Also

• Mary used great animations that helped for a better understanding of the Bio-Nanosensor Transporter concept.

• I particularly like the criticism given to the paper, where she mentioned some missing details in the paper about the stability of the MTs and of course the toxicity of the MTs, but also including potential future work to further develop portable, cheap and more sensitive and stronger sensors.

G6

Review Nanosensing, Microtubules by Jung Hwan Woo

Jung Hwan Woo

Questions

• What is the mechanism to the selective inhibition of the rapid dividing cells?

• Is there a way for the MT’s to differentiate a cancer cell from a normal cell that is rapidly dividing, for example, cells on a wounded skin?

• Has there been animal tests on the effectiveness of the MT’s on cancer cells?

• What was the method used to determine that the MT’s selectively inhibited rapidly dividing cells?

U6

Review Nanosensing, Microtubules by Group U6

Nanosensors:Microtubules

By Mary CoanChemical Engineering

Reviewed by: Group U6 - Pavitra Timbalia, Michael Trevathan, Jared Walker

The speaker maintained a appropriate tone which was easily understandable.

She maintained eye contact with the audience and didn’t not read off the slides.

She seemed confident and knowledgeable of the subject of the presentation.

Review of oral presentation

There was a lot of material covered in the slides, perhaps to fast to comprehend in the amount of time given. It became hard to follow at some points.

The graphics and text were well balanced, and the graphics aided a great deal in trying to understand the content of the presentation.

The speaker covered all relevant topics from an introduction of the research to how it can be furthered. It might have been nice to have heard some of the opposition to such research and or more research in the same field, but overall the presentation was well balanced and informative.

Review of presentation content

G4Rebuttal: Biomedical Sensing


Comments• G2: It was not mentioned in the introduction any of the design

considerations for a sensor like accuracy, repeatability, resolution, hysteresis, linearity etc…

A:/ I decided to make a much more friendly introduction to the topic, instead of going on technical details that might have done the introduction more obscure. Notice that a high percentage of the audience is at the undergraduate level and they are not so familiar with the nanotechnology world. I think that the audience’s academic background guarantees that they have a ‘feel’ of what to expect from a sensing device (accuracy and so on..)

My main focus in the introduction was to give the audience just the necessary information to be able to follow through the presentation of the paper results. The paper results were not focused in the sensor calibration (resolution, accuracy, etc…), but on the ability to actually ‘sense’ at such small concentration.

Comments• G2: Some technical terms were not defined, like Schottky Barrier,

nanoribbon, streptatividin, photocleavable-antigen pair, some terminology was confusing, like 1 anti-PSA, 1 anti-CA15.3…

• A:/ The 2-dimensional character of the nanoribbon was mentioned in contrast to the 1-dimensional character of the nanowire. Moreover, it was pointed that this was one of the reasons why was easier to work with nanoribbons.

• It was mentioned that strepatavidin/biotin is an antibody/antigen pair widely used in this kind of studies

• Photo=light, Cleavable=break. A photocleavable antigen pair wherein an antigen breaks loose under UV light. This was explained since this is what enables the transfer of antigen from the ‘big’ chamber to the ‘small’ chamber

• 1 anti-PSA: the antibody corresponding to the antigen PSA. Use the same reasoning for 1-anti-CA15.3

• The point of the Schottky barrier was only brought up to point the similarities of the electrical behavior of the presented nanosensor to that of a conventional Schottky barrier FET

Comments• G2: The microfabrication process was not illustrated, and the

nanowire functionalization procedure was also not shown. The technical challenge implied on making the nanodevice and making it work was not explained…

a) The focus of the presentation was centered on the functioning of the device, not on the fabrication of the devices. Therefore, only I few remarks about the fabrication process were done.

b) The presentation showed three mile-stone papers on the development of nanosensors since 2001 up to date. Throughout the presentation, it was constantly discussed the challenges at-the-paper-date and the approach used in the paper to solve it. Moreover, some of these challenges were pointed to explain the transition from a nanowire- to a nanoribbon based sensor. All the three papers were about ‘making it work’. If the technical challenges refer to their fabrication, answer a) applies

Comments• G6: How effective are nanowires in nanoFET in detecting such charge

transfer?

• Nanowire technology correspond to the first paper presented. The plots shows that concentrations in the order of picomolar were detected. This corresponds to the binding of about six antigens to the functionalized nanowire. It is noteworthy, though, that this sensitivity occurs under specfic conditions. For instance, the presence of a buffer solution is a ‘must’. However, there are ways around this, as shown in the third paper

Comments

• G6: What methods are currently being used to fabricate these nanosensors?

• The use of silicon nanoribbons makes it preferable to use top-down approaches as e-beam litography and selective etching, using silicon on insulator wafers as starting materials.

• G6: Could this be batch processed for cost reduction and large scale production?

• Yes, but it is not the main concern just now. The current primary objective is to make the technology work properly

Comments

• G6: What are the methods in detecting which antigen is binding with which antibody in the nano-scale sensing

• If your question refers as to what antibody must the sensor be functionalized with in order to detect an specific antigen, I must say that usually labeled technology (fluorescence assays) has been traditionally used to determine what antigen binds with what antibody. However, the implementation of better biosensors like the one presented in this study significantly would speed up the screening of these pairs, which itself would help to create more selective nanosensors

• G6: Is the number of charge transferred different for different antigen-antibody combination?

• Yes, it is different because different compounds modify the electron density in the neighborhood of nanosensor surface in slightly different ways. As you can see for the rsults of the third paper, identical concentration of different antigen produces a different slope in the response curve

Comments

General Comments

• I agree with comments pointing to the length of presentation and the use of filler words. I will work on improving my presentation skills. Also I will improve the graphic labels

• There was some mixed feelings about the ‘informal approach’ used in the presentation. So I guess I will use a more formal approach in the up coming presentation

G1Review : Biomedical Sensing

By Edson P. Bellido Sosa

The presenter described in detail what a bio-sensors is and what we want to detect in biomedical applications. He explained why one wants a label free detection. He analyzed 3 papers. The first is based on a silicon nanowire functionalized with amine group and bioting in a FET configuration, they measured the change in pH and he explained how the nanosensor works. In the second paper they test a silicon nanoribon and measured the change in conductivity according to the concentration of streptavidin. Finally in the third paper they used microfluidic channel technology to include a filtering step in the process of sensing, in this paper they measure the concentration of PSA and CA15.3, which are biomarkers for prostate cancer and breast cancer respectively, using the change in conductivity in a silicon array.

Future research would be about the use of other nanomaterials for nanosensing to increase the sensitivity and selectivity. Also more research needs to be done in the area of design optimization of the lab on a chip structures to avoid false positives or negatives. Also other interesting area is the discovery of new biomarkers which are directly related to a disease.

http://image.absoluteastronomy.com/images/encyclopediaimages/f/fr/free_psa.png

G2

Review Biomedical Sensingby Alfredo Bobadilla

It was shown how a functionalized Si nanowire can be used for electrical detection of very low concentration of molecularbiomarkers. The working principle and performance of the biosensing device was illustrated.

Nevertheless it was not mentioned in the introduction any of the design considerations for a sensor like accuracy, repeatability, resolution, hysteresis, linearity, etc.

Some technical terms were not defined, like Schottky barrier,nanoribbon, streptatividin, or photocleavable-antigen pair. And some molecular biology terminology was also confusing like‘1 anti-PSA, ‘1 anti-CA15.3 which was shown together withpictures.

The microfabrication process was not illustrated, and thenanowire functionalization procedure was also not shown.The technical challenge implied on making the nanodevice andmaking it works was not explained.


Review of biomedical sensing lecture

G3

Review Biomedical Sensingby Mary Coan

Review

Overall a great presentationNanosensors are used for early cancer

detectionNanosensors using nanoribbons are more

easily fabricated than nanowires and have similar sensitivity

Explained in detail sensors and nanosensors◦Graphics were used as aids

Review

Presented a significant amount of information about bio-nanosensors in a fun and educational way

Assessment of the paper and topic was spot on

G5Review Biomedical Sensing

by Norma Rangel

Biomedical sensing (Nano-bio-sensors), by Diego A. Gomez-Gualdron

• Diego did a very educational and organized presentation about sensors for biomedical applications, with an emphasis on biomarkers used to detect cancer.

• The presentation is very self explanatory and didactic, the papers chosen are state of the art and very promising for early detection because they are able to detect in concentrations in the range of 4-10 ng/ml

G6

Review Biomedical SensingBy Jung Hwan Woo

Jung Hwan Woo

How effective are nanowires in nanoFET in detecting such charge transfer?What methods are currently being used to fabricate these nanosensors? E-beam litho? X-ray? Could these be batch processed for cost reduction and large-scale production?

What are the methods in detecting which antigen is binding with which antibody in the nano-scale sensing? Is the number of transferred charge different for different antigen-antibody combination?

G5Rebuttal: Carbon-Nanotubes Applicattions

--MISSING--

G1Review of Carbon-Nanotubes

Applicattionsby Edson Bellido

The presenter explained the synthesis methods currently being used, the most important properties of carbon nanotubes and a vary large variety of applications, focusing principally on the used of CNTs for imaging and therapeutics. She point out the challenges and opportunities of using CNTs in vivo.

http://www2.polito.it/ricerca/micronanotech/act/immagini/cnt_01.jpg

The presenter discuss about the importance of the functionalization of CNT to be able to use it in medicine applications since the CNTs by itself are not soluble on water and form bundles that could be toxic and can accumulate in the organs.

The overall presentation was good. However, from my point of view, it would have been better if instead of presenting that large variety of applications, the presentation have focused on maybe one or two and discuss more about the experimental details such as functionalization process the change in properties after functionalization and the physics behind each process.

Review of CNTs applications lecture

It was summarized very well the physical properties of CNTs whichmakes it an outstanding material.

A very broad range of applications for carbon nanotubes was shown. Nevertheless no application was analyzed carefully enough, I mean the methodology and results were not analyzed in detail.The basic working principle used in the applications was not illustrated.

The challenges shown in the last slide were general problems currentlyfaced to make CNTs applications commercially available. The presenterdidn’t make any suggestion on how to solve those problems.


Review:Carbon Nanotube

ApplicationsBy Mary Coan

Review

Overall a GREAT presentationCarbon Nanotubes have many properties

that can not be found in any other material

Have many applictions:◦Diodes, Capacitors, Flat panel displays, etc…

Challenges were discussed◦Control of diameter◦Manufacturing costs

Explained many different applications, processes, mechanisms and challenges

Review

Discussed typical questions regarding CNTs◦Example: CNTs in Medicine (Good?)

Discussed the opportunities and challenges for each question discussed

The toxicity of CNTs was discussedShe did a wonderful job by using many

images to describe what she was discussing.

The level of the work presented fits the audience very well.

Review Carbon Nanotubes (G5)

Diego A. Gomez-Gualdron

CNT properties• Outstanding electrical conductivity (six times copper)

• Outstanding mechanical properties (tensile strength, yet flexible)

•Field emitters (they can increase resolution in spectroscopy)

•One-dimensional thermal conductivity

•Easy functionalization

•Enhanced mass transport through the nanotube

Production methods

Large scale

• Chemical Vapor Deposition

Small scale

• Laser Ablation

• Arc discharge

CVD schematics

catalyst

Substrate

Nanotube

Precursor gas

Modified from ASIN group

Applications

• Microchips elements of reduced size

• Composite materials for extreme conditions

• Nanosensors for chemical and medical applications

• Drug delivery and cancer treatment

Assessment

• Electronic applications depending on selective production of pure semiconductor/conductor nanotubes at large scale

• Biomedical applications still have to solve citotoxicity issues and treatment effectiveness

• Mechanical applications pending on nanotube cost issues

Review

• A good presentation overall. A wide range of applications were shown. Good assessment of status and challenges for each application. Good fluency despite the recurrence of filler words and mumbling during slide transitions. The speaker was confident during the presentation, although not so much during questions. The figures/text balance on the slides could improve

• It would have been nice to stress what particular property of the nanotube is being taken advantage of for each specific application (why is the nanotube used for that specific application and not another material)

Jung Hwan Woo

Review for G5

Jung Hwan Woo

Jung Hwan Woo

Questions

• On the nanotube textile slide, how are nanotubes separated into the rope of nanotubes? More details on the initial process to grabbing the first few threads of NWs may help.

• Is the “preclinical human-tumor model” on the slide 32 a computer model simulation or a biological experimental model?

• What makes CNTs good candidate over other materials/structures for a biomedical device?

• Are there any other structures or materials that can also be used for the applications discussed in the presentation?

G6Rebuttal: Piezoelectricity

Jung Hwan Woo

Comments

• Thank you all for constructive comments. I will work harder to provide future research suggestions and to include more current research being carried out. I will also include suggestions to how the experiment is performed to improve the results.

Q&A• Q: Why so little advance in the topic from 2006-2010 (judging for the

presentation)? There is a fundamental obstacle? Have other nanoarrays be tested? Is this the best alternative to harvest energy at the nanoscale?

• A: I believe that the limitation comes from the nature of the material. The piezoelectricity can only yield little power per area. Increase in the dimension of the array could yield higher power but it will eliminate these generators for nanotechnological use. However, it is certain that this method is one of the better ways to harvest energy for nanorobots as the external power source is completely eliminated.

• Q: Is the only work done? Are there many other people working on this? Was the presented work a breakthrough?

• A: This topic is a hot research topic these days. There are many more papers out there, though the Science paper was a bright original idea that suggested new strategy in powering nano-devices.

Q&A

• Q: Could you better explain why current is measured when AFM tip exerts stress on nanowires and how it is measured?

• A: For a free-standing piezoelectric nanowire under stress, one side will be compressively strained and the other tensilely stressed. This produces a flow of electron in a clockwise (or counter-clockwise) direction in a 2D model. If there is a source of electron, in this case the AFM tip, electrons from this source will be pulled to the same direction as the electron movements due to the electric field. At the same time, AFM could also measure the current out of the AFM tip.

G1Piezoelectric Nanogenerator

Review


The presenter describe the basic concepts about piezoelectricity and how this phenomenon is being used at macro-scale. He also described why ZnO is being used for this application. He explained the synthesis process and the experimental setup. He also discuss the use of Polyvinylidene fluoride for nano-piezoelectric applications.

Since the power obtained form this source is low and the energy consumption of nano-electronic devices is in the same range. From my point of view this technology will have a impact in how we will get energy for future nano-devices. And open the possibility of the fabrication of self powered nano-electronic devices.

From my point of view the presentation was good and the topic was very interesting, maybe he could have given more examples of devices being fabricated currently. The group of Dr. Zhong Lin Wang, creator of this technology, is working extensively in this area and have recently published a paper in “Nature Nanotechnology” where they use this technology to power up a pH sensor and a UV sensor and using a lateral integration of 700 rows of ZnO nanowires they produce a peak voltage of 1.26 V.

"Self-powered nanowire devices " Sheng Xu, Yong Qin, Chen Xu, Yaguang Wei, Rusen Yang and Zhong Lin Wang, Nat. Nanotechnol. Online

http://spie.org/Images/Graphics/Newsroom/Imported/101/101_fig2.jpg

http://www.nanoscience.gatech.edu/zlwang/paper/2010/10_NN_01.pdf



G2Review of Piezoelectricity

by Alfredo Bobadilla

Piezoelectricity lecture’s review

The introduction part illustrated very well the basic working principle of a piezoelectric material. Nevertheless it was not illustrated the physical aspect behind it, i.e. how the mechanical flexion or the change in geometry cause the electric field.

I think the video shown to illustrate an experiment didn’t have enough image quality, it was not possible to appreciate what was happening there.

It was not explained how the AFM work, and being the AFM the scientific instrument used to make the experiment with ZnO nanowires, it was not clear enough how the experiment was performed. So it was not mentioned what’s the challenge or technical difficulties when performing that experiment.

No suggestion was given on what additional work is necessary to make the ZnO nanowire more efficient for harvesting energy or for controlling the ZnO nanowire synthesis, i.e. crystal directions, to be able to use other vibrational modes.


REVIEW:ZNO NANOWIRE ARRAYPIEZOELECTRIC NANOGENERATOR

By Mary Coan3/12/10

Review

Described what a Piezoelectric effect is Governing equations and Definition

Gave examples of the applications for a Piezoelectric efect Biological Nanowire

Gave Advantages for ZnO Fabrication ZnO nanowires can have a PZ effect

Review

Gave advantages and disadvantages of PZ polymeric nanogenerator Discussed materials, fabrication and results

Overall the presentation held a lot of information Used images and movies to explain certain

hard aspects Could have transitioned better between

topics From ZnO wires to NanoFibers Given background on Nanofibers

G4Review Piezoelectricity


Piezoelectricity

http://en.wikipedia.org/wiki/Piezoelectricity

Applied mechanical stress

Resulting voltage

• Piezoelectric materials respond to mechanical stimuli by producing and instantaneous current (or voltage) due to polarization changes caused by the shape change

• The effect might potentially exploited to harvest energy in nanodevices. For instance, to power-up a nanorobot

• A common material in nanotechnology applications, ZnO, has piezoelectric properties that makes it a suited candidate for harvesting energy at the nanoscale

A prototype device

Wang. Z. L., et. al.

ZnO nanowires on a silver (Ag) plate

•The schottky barrier behavior of the ZnO/metal systems makes the generated current unidirectional allowing to store energy.

•The ZnO material is biocompatible allowing to use the material for nanodevices meant to be introduced to the body and work at in vivo conditions

AFM tip

Voltameter

Performance:A scanning with an AFM tip is done along the surface. The mechanical stress on the ZnO nanowire originates from the tip movement and the voltage generated is measured with an incorporated voltameter that registered a production of 64 meV per squared micrometer

Comments• It appears that the energy production per area is not high enough

for the size/power-input required for the implementation of this arrangement as a primary energy source in a nanodevice. It is perhaps difficult to increase the performance of an individual nanowire without exploring a new material, but maybe another geometrical configurations of the nanowire arrays can lead to an efficiency increase

• The mechanical stimulus produced by the AFM is perhaps not a good model of how the array would be stimulated in another environment (for instance by collisions against the blood vessel walls in a nanorobot). How the specific fashion the mechanical stress is applied affects performance?

Review• An interesting topic was presented. However there was little focus on the most current paper

(nanoletters 2010), and rather was limited to an older one (science 2006). Even though the older paper was suitable to show the geometry of the nanoarray and how the device could work and its performance measured, there were many things left in the air. Why so little advance in the topic from 2006-2010 (judging for the presentation)? There is a fundamental obstacle? Have other nanoarrays be tested? Is this the best alternative to harvest energy at the nanoscale?

• The presentation was too short because the critical analysis that follows to the presentation of the work was completely missing. The pros and cons of the work were not discussed. The main problems to solve were not pointed out. Other alternatives existent, in development, or proposed were not shown. In summary, the audience was presented a nice and interesting work , but was not told of how this work stands among other works in nanotechnology. Is the only work done? Are there many other people working on this? Was the presented work a breakthrough?

• Other than the aforementioned points, it was a good presentation, but perhaps fell short in scope.

G5Review of Piezoelectricity

by Norma Rangel

ZnO Nanowire Array Piezoelectric Nanogenerator, by Jung Hwan Woo

• Jung gave a very clear explanation of piezoelectricity, some background and presented a video where the actual concept of a piezoelectric generator was shown working and suggested an interesting application for generation of electricity from human footsteps in places where there is a big traffic such as train stations.

• It was unclear for me how the current was measured in the ZnO nanowires from one side of wire to the other if the wires have a nanometer diameter and at the same type have both compressive and tensile stress.

G1Rebuttal: Nanowire photonics


Comment: The introduction part didn’t include basic concepts from spectroscopy, necessary to be able to interpret the results from the presented research work.

Yes, I did not considered necessary to mentioned those basic concepts of characterization techniques since I thought the audience had this knowledge. However, during the presentation I have noticed that this was not the case.

Comment: It should have been illustrated the design requirements and working principle of at least one potential application such as the procedure to make a logic in a photonic computer or the remote detection of threat agents. I chose to only talk about one application in detail since the time of the presentation was limited.

Comment: Hard to understand diagrams without explanation

I did not want to include much text on slides. I wanted to include important diagrams in the same slide to compare the different characterization techniques. But I explain the details on the talk.

Comment: The presentation was based in only one paper, which refrained the audience from evaluating how the presented research stands on the whole field. I chose to talk about one application in detail since the time of the presentation was limited and photonics is very wide field.

Comment: We have talked about toxicity of nanowires for half-semester long but no one yet came to a conclusion. I Agree. However I think the problem is that not much research is being doing in this field in comparison with research doing in applications and basic science of nanowires and other nanostructures.

Photonic nanowires – Lecture review

The introduction part didn’t include basic concepts from spectroscopy, necessary to be able to interpret the results from the presented research work.

It was shown in detail only the procedure to synthesize the nanowires.It should have been illustrated the design requirements and working principle of at least one potential application such as the procedure to make a logic in a photonic computer or the remote detection of threat agents.

Elemental devices like‘optical microcavity’ or ‘ring resonators’ which enable many photonic applications were not mentioned.

Limitations on the controlled connection or assembly of nanowires, which isfundamental to enable potential applications, were not illustrated.


G3 REVIEW:NANOWIRE PHOTONICS

By: Mary Coan3-30-10

Review

Listed applications for Photonics Gave positive aspects of Nanowires Discussed Formation of Nanowires

Hard to understand diagrams without explanation

Used graphs and diagrams to convey message Did not use bulletins so I can not follow

Review G1-Photonics


Photonics• Consist in the technical application of light (generally visible) in order

to perform a task (e.g. sensing, information processing)

A signal transmitted by light traveling through optic fibers

www.digitalization.wordpress.com

www.wikipedia.com

mechanism

• The decay of an excited electron (with energy E2) to a non-excited state (with energy E1) is accompanied with the emission of a photon with energy hv=E2-E1

Nanowires

A nanowire emitting light Structure of a Silica nanowire

www.nersc.govwww.fas.harvard.edu

* Nanowire are cylindrical structures (typically semiconductors) with a high aspect ration an a diameter in the nano scale. Being semiconductors, the light they emit depends on their band gap (the energetic difference between the valence and conduction band)

• If one can tune the nanowire band gap, then you can control what light wavelength is emitted

• ‘ALLOY’ COMPONENTS!!!

Tuning the Band GapA rule of thumb is that if one mixes component A with a band gap EA and component B with a band gap EB, such that the resulting fraction are XA and XB, the resulting band gap is given by:

EAB=XAEA+XBEB (1)

Let us mix GaN and InN in a nanowire!!!

Increase of In molar fractionNature Mater. 6, 951–956 (2007).

•Change in the emitted light with composition

•Equation (1) holds•Change in the emitted light with composition

Incr

ease

of I

n m

olar

frac

tion

REVIEW• The speaker made a good job explaining the material contained in

the slides. However, the presentation fell short in its scope. Photonics is a very wide field. Although understandable that it can hardly be covered in 50 min, a greater effort in making the overview should have been made, so the bigger picture of the field could have been captured

• The presentation was based in only one paper, which refrained the audience from evaluating how the presented research stands on the whole field. Moreover, the paper presented was likely not the latest advance on the field as it was published three years ago.

REVIEW• The presentation was too short (13 slides), and the speaker missed the

opportunity to compensate the use of just one paper, by explaining it thoroughly, more specifically, the experimental procedure. Even when the synthesis of nanowires was covered in the first presentation of the semester, there was more to it. For instance, there are problems specifically related to the alloying of GaN and InN.

• Also, the speaker misinterpreted the experimental procedure. Particularly, how the control of the concentration was made. The speaker interpreted that this was made by changing the distance of the substrate to the nozzle, when in fact is made by controlling the vapor pressure of the Ga an In precursors (therefore the independent heating sources), as it can be read in the actual paper.

Review for G1

Jung Hwan Woo

• Details on these research fields can really help improve the conclusion of the presentation

• What are the fields that can take advantage of large scale integration?• We have talked about toxicity of nanowires for half-semester long but no one yet

came to a conclusion. Maybe it is time for some of the presenters to come up with something remotely close to supporting for or against the usability of nanowires on human body based on the toxicity.

• Example of photonic computing could help the audience to understand what it is. Same for single photon sources

G2Rebuttal: Molecular circuits based on

NDR composites


Molecular circuits based on NDR composites

Review


The presenter explained how a MOSFET, currently use in electronics, works and its electrical characteristics. He explained how a logic gate works and how we use this logic gates to do computation. He Also point out the problem of power consumption and noise.

He explained the basic concept of NDR and show examples of NDR in CNTs.He also explained NDR behavior on DNA. However personally I do not think this kind of behavior could be consider NDR since is consequence of a chemical reaction. For the case of the molecular junction the behavior it resembles a NDR.

He also explained the concepts of NDR circuits and the Nanocell. He showed how these circuits could work and how the assemble of this could be used to create molecular system that can do computation.

The Overall presentation was good. The introductory part was too long and did not give much time to go into more detail in the papers he showed. We missed the opportunity to ask more questions and especially considering that the authors of one of the discussed papers were present in the audience.

G3 REVIEW: MOLECULAR CIRCUITS BASED ON NDR COMPOSITES

By Mary CoanPhD Chemical Engineering4/01/10

Review A lot of information was covered in the

introduction section Explained

MOSFET On and Off State Electrical Characteristics

CMOS NAND Electrical Map

Power Consumption Equations Diagrams Good versus poor results

Mentioned Noise Explained using Diagrams, Charts, and equations

Discussed Resonant tunneling Diodes in detail

Review Used Graphs and images to convey

important device structure and electrical characteristics of NDR’s

Used several examples to explain how NDR behaves in molecules and nanodevices

Discussed simulation results along with actual results

NanoCell Concept Programming/Training Chemically assembled

Future Research was also discussed

Review

Overall the presentation went over a lot of information in a short amount In a concise orderly fashion

Used Images and Graphs to depict relevant information Captured the attention of the audience

The information provided was current and correct

G4Review of Molecular circuits based on

NDR composites

by Diego Gomez

NDR• NDR stands for Negative Differential Resistance, which is a

property of certain circuit elements where the current decreases as the voltage is increased. This occurs in certain voltage ranges and it is due to certain materials composing the circuit

Science (2009), Vol 323, 1026

NDR region in a FETCertain materials on certain substrates produce this kind of behavior. For instance, styrene on a (100) silicon surface

Nano Letters(2004), Vol 4, 55

NDR in logics

The high peaks correspond to a ‘1’ or a ‘yes’ signal

The deep valleys correspond to a ‘0’ or a ‘no’ signal

The use of NDR technology reduces the complexity of logic circuits

PROBLEMS TO DEAL WITH

Power dissipation

Size reduction

Noise

Nanocell Nanocell is a nanostructured circuit made out of

molecules and nanoclusters analogous to the structure of current macroscale logic circuits.

IEEE transactions on nanotechnology(2002), Vol 1, 101

Macroscale circuit Nanoscale circuit

REVIEW

The speaker improved greatly respecting to his first presentation. Yet, he needs to keep working in the following aspects:

1) English fluency: Even the most brilliant of the scientists will fail to catch the public’s attention during half an hour without fluency. People will easily get distracted due a low tone of voice, difficulty to understand words and lack of fluidity. This ends up affecting coherency and makes you going around the idea you want to convey without being able to go to the point. Also, it will slow you down and make your presentation longer than expected

REVIEW 2) Slide design: A set of well-thought slides makes a presentation much easier to

follow:

- Think what the audience needs to know to follow through the presentation, and design the slide sequence accordingly

- Use at least font 18 for the smallest text in the slide (apart from figure references and similar) and use different font sizes for main points and secondary points.

- Use space evenly and smartly, do not just splash some text and some graphs onto each slide. Use bullets and short sentences. Do not stuff the slides with text

REVIEW

I think the speaker tried to make a good effort in the introduction. However, the key word in the title is ‘NDR’, and the speaker took too long to get there. Moreover, checking the slides, I did not find a particular slide to illustrate this point, which is the basic point of the presentation

I think the speaker failed to stamp his own point-of-view in the ‘further research’ section, and limited himself to briefly name some recent works on the field rather than assess and critically propose his ideas

G5

Review of Molecular circuits based on NDR composites

by Norma Rangel

--MISSING--

Review for Molecular circuits based on NDR composites

Jung Hwan Woo

• The font size is too small and each slide packs too much information to efficiently support the presentation.

• The speech was a bit too slow to contain what needed to be presented within the allotted time.

• The introduction to the concept seemed more than enough so that it exhausted the time needed for more important materials.

• Explanation to why negative-differential resistant behavior is present for each case can be improved to help the audience to understand the concept.

G3Rebuttal: Nanoelectromechanical Systems

NMEs

Mary Coan

G1

Review : Nanoelectromechanical Systems (NMEs)

Edson Bellido

(MISSISNG)

Alfredo Bobadilla

G2


NEMS lecture review

The theme was not well organized. It should have been emphasized the different novel methods enabling NEMS development, i.e. laser micromachining for 3D structures,DRIE for high aspect ratio structures, soft lithography for biocompatible devices, etc.

The essence of different working principles used for NEMS sensors and actuators should have been mentioned, i.e. thermal, electrical, piezolectric, piezoresistive, magnetic and electrostatic.

Essential electrical and mechanical concepts such as stress & strain and resonant frequency & quality factor were not illustrated.

The cantilever beam was not correctly illustrated when it was mentioned on applicationsfor chemical sensing or mass spectrometry, it was not explained what factors contributeto getting a high sensitivity to mass or pressure.

The cantilever beam is the basic element for a broad range of applications and its basic working principle was neither well depicted.


G4


Diego Gómez

(MISSING)

G5


Norma Rangel

(MISSISNG)

Jung Hwan Woo

G6


• I believe that MEMS/NEMS devices have longevity problems as nano-structures tend to “wear out” pretty fast. How is this being resolved?

• Another problem with MEMS devices is the stiction problem during and following the etch of sacrificial layer. How are people addressing this issue?

• How do manufacturers batch fabricate NEMS devices and maintain the same physical/electrical/thermal properties? In such small scale, the variation of properties that moving parts have could be very large.

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G1 Rebuttal: Carbon Nanotube Chirality Edson P. Bellido Sosa.

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