Transcript Slide 1

G1
Rebuttal: 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.
G2
Review Controlling carbon nanotube chirality
by Alfredo Bobadilla
Review of “Process to control carbon nanotube chirality”
Nanotech course – Alfredo
Bobadilla
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.
G3
Review:
Process to control carbon nanotubes
chirality
By Mary Coan
2/9/2010
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
G4
Summary ‘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
Diego A. Gómez-Gualdrón
Approach 1
Nanotube ‘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
Diego A. Gómez-Gualdrón
Approach 2
Altering nanocatalyst structure
FCC Ni
BCC Fe
Metals with different structure are alloyed to form a nanoparticle whose structure is
concentration-dependant
Diego A. Gómez-Gualdrón
Approach 2
Panels a,b,c, and d illustrate how the chirality distribution is affected by concentrationdependant changes in the nanoparticle structure
Diego A. Gómez-Gualdrón
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
Diego A. Gómez-Gualdrón
Recomendations
• Study the relationship between particular
catalyst structures and chirality obtained
• Study how effectively the catalyst structure
can be controlled during synthesis
Diego A. Gómez-Gualdrón
G5
Review Controlling carbon nanotube
chirality
by Norma Rangel
CNTs chirality
Edson Bellido
Taken from
wikipedia
Good presentation
Covered also fabrication and few
applications
I think the material was covered
with enough information
He 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
G2
Rebuttal: Nano electromechanical oscillators
Alfredo Bobadilla
Nano electromechanical oscillators – ‘Rebuttal’
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.
Alfredo D. Bobadilla
G1
Electro-Mechanical Oscillators
Review
Edson P. Bellido Sosa
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 nanodevices.
G3
Review: Electromechanical Oscillators
By Mary Coan
2/12/2010
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.
G4
Summary 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.
Nature 431, 284-287 (16 September 2004) | doi:10.1038/nature02905
•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.
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 Oscillators
by Norma Rangel
Electromechanical oscillators
by 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 Oscillators
by 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?
Jung Hwan Woo
G3
Rebuttal: 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-antibodysandwich (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 bionanosensor 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.
Alfredo D. Bobadilla
G4
Microtubules 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 pointof-care approaches.
G5
Review Nanosensing, Microtubules
by Norma Rangel
Nanosensors: Microtubules
By 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
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?
Jung Hwan Woo
U6
Review Nanosensing, Microtubules
by Group U6
By Mary Coan
Chemical 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.



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.
G4
Rebuttal: Biomedical Sensing
Diego A. Gómez-Gualdrón
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
Comments
• 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
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
G1
Review : 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 Sensing
by Alfredo Bobadilla
Review of biomedical sensing lecture
It was shown how a functionalized Si nanowire can be used
for electrical detection of very low concentration of molecular
biomarkers. 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 with
pictures.
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 works was not explained.
Alfredo D. Bobadilla
G3
Review Biomedical Sensing
by Mary Coan
Overall a great presentation
 Nanosensors are used for early cancer
detection
 Nanosensors 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

Review
G5
Review 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 Sensing
By 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 antigenantibody combination?
Jung Hwan Woo
G5
Rebuttal: Carbon-Nanotubes Applicattions
--MISSING--
G1
Review of Carbon-Nanotubes
Applicattions
by 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.
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.
http://www2.polito.it/ricerca/micronanotech/act/immagini/cnt_01.jpg
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 which
makes 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 currently
faced to make CNTs applications commercially available. The presenter
didn’t make any suggestion on how to solve those problems.
Alfredo D. Bobadilla
Review:
Carbon Nanotube
Applications
By Mary Coan
Overall a GREAT presentation
Carbon 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 discussed
 She 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
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
CVD schematics
Precursor gas
Substrate
Nanotube
catalyst
Small scale
•Laser Ablation
Modified from ASIN group
•Arc discharge
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)
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?
Jung Hwan Woo
G6
Rebuttal: 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.
G1
Piezoelectric Nanogenerator
Review
Edson P. Bellido Sosa
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 nanoelectronic devices.
http://spie.org/Images/Graphics/Newsroom/Imported/101/101_fig2.jpg
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
G2
Review 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.
Alfredo D. Bobadilla
By Mary Coan
3/12/10
REVIEW:
ZNO NANOWIRE ARRAY
PIEZOELECTRIC NANOGENERATOR
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
G4
Review Piezoelectricity
Diego A Gomez-Gualdron
Piezoelectricity
Applied mechanical stress
• Piezoelectric materials respond to
mechanical stimuli by producing and
instantaneous current (or voltage) due to
polarization changes caused by the shape
change
Resulting voltage
• The effect might potentially exploited to
harvest energy in nanodevices. For
instance, to power-up a nanorobot
http://en.wikipedia.org/wiki/Piezoelectricity
• 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
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
Wang. Z. L., et. al.
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.
G5
Review 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.
G1
Rebuttal: Nanowire photonics
Edson P. Bellido Sosa
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 is
fundamental to enable potential applications, were not illustrated.
Alfredo D. Bobadilla
By: Mary Coan
3-30-10



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
Diego A Gomez-Gualdron
Photonics
• Consist in the technical application of light (generally visible) in order
to perform a task (e.g. sensing, information processing)
www.digitalization.wordpress.com
mechanism
www.wikipedia.com
A signal transmitted by light
traveling through optic fibers
• 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
* 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)
www.fas.harvard.edu
www.nersc.gov
• If one can tune the
nanowire band gap, then
you can control what light
wavelength is emitted
• ‘ALLOY’ COMPONENTS!!!
A nanowire emitting light
Structure of a Silica nanowire
Tuning the Band Gap
A 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!!!
•Equation (1) holds
•Change in the emitted light
with composition
Increase of In molar fraction
•Change in the emitted light
with composition
Increase of In molar fraction
Nature Mater. 6, 951–956 (2007).
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
G2
Rebuttal: Molecular circuits based on
NDR composites
Alfredo D. Bobadilla
Molecular circuits based on
NDR composites
Review
Edson P. Bellido Sosa
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 Coan
PhD Chemical Engineering
4/01/10
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
G4
Review 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
Nano Letters(2004), Vol 4, 55
Science (2009), Vol 323, 1026
NDR region in a FET
Certain materials on certain substrates
produce this kind of behavior. For instance,
styrene on a (100) silicon surface
NDR in logics
The use of NDR technology reduces the complexity of
logic circuits
 The high peaks correspond
to a ‘1’ or a ‘yes’ signal
 The deep valleys correspond
to a ‘0’ or a ‘no’ signal
PROBLEMS TO DEAL WITH
 Power dissipation
 Noise
 Size reduction
Nanocell
 Nanocell is a nanostructured circuit made out of
molecules and nanoclusters analogous to the
structure of current macroscale logic circuits.
Macroscale circuit
Nanoscale circuit
IEEE transactions on nanotechnology(2002), Vol 1, 101
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.
G3
Rebuttal: Nanoelectromechanical Systems
NMEs
Mary Coan
G1
Review : Nanoelectromechanical Systems
(NMEs)
Edson Bellido
(MISSISNG)
G2
Review : Nanoelectromechanical Systems
(NMEs)
Alfredo Bobadilla
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 applications
for chemical sensing or mass spectrometry, it was not explained what factors contribute
to 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.
Alfredo D. Bobadilla
G4
Review : Nanoelectromechanical Systems
(NMEs)
Diego Gómez
(MISSING)
G5
Review : Nanoelectromechanical Systems
(NMEs)
Norma Rangel
(MISSISNG)
G6
Review : Nanoelectromechanical Systems
(NMEs)
Jung Hwan Woo
• 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.