cc
Thank you for watching >> Cassie Immel: Good evening.
I'm Cassie Immel from here Wednesday Nite at the Lab.
This evening, atwe have Dr. Xudong Wang.r.
He is an assistant professor
Sciences and Engineering at the University of Wisconsin-Madison.
He received his PhD from Georgia
Currently, his research includes Tech in 2005.
nanostructures. celHe is the recipient of theof
Darpa Young Faculty Award,
and the Ross Coffin Purdy Award. the Non-Tenured Faculty Award,
to you, Dr. Wang. Without fur[applause], I present
Xudong Wang: Thank you. Can everyone hear me?
Good. Thank you and good evening.
It's my pleasure to be here,
Happy New Year, by the way. So, my talk will be some of my
research I've been doing for the
about nanoscale and mechanical last five or six years, which is
We have named it nanogenerators. energy harvesting.
harvesting. SoMost of the folks are ony
nanotechnology and mechanics
So as we know, contrary to -- stage of technology explosion,
and you can see small electronic
smaller and faster and faster. devices getting smaller and
nanotechnology and electronics. TSo, you will notice that allr
this nice technology can be achieved with these very small,
tiny chips. But the one thing that is
lagging behind is the battery.
of our computer, heaviest part So you can see the heaviest part
It's the majority of the body of of our cell phone is a battery.
So, there's many research that's the device.
reduce the size and improve the capacity of the battery to match
the development of the
So that's why our research is going on here.
And in the biomedical device
So right now, as we know, there's many devices for the
implantable devices used for the
For example there's brain sensors, as we see right here,
and pacemakers. There are some sensors that
people need to put inside their body to help their health,
monitor their health, and to help our body improvement.
So, all these devices are very nice and very small.
But they also need batteries, so that's a key challenge
for those devices.
the pacemakers, people need to Some people, for example
eight or ten years. reFor other sensors, we alsoy
need to charge the batteries
So the best way that people think about it for those devices
is to use the energy from the surroundings.
For example, for the power
we need, is we need a small ssize, and they'll need to bet
biocompatible, and then need to be very, they need to last
very long.
lifetime. So people think about, instead
of uses more battery, the best
the environment, basically from way is our body itself.y from
Now, we'll talk about how we
Right now, there are many, many catechniques for us to harveste.
energy from the surroundings. A lot of things we know about is
the biofuels, the hydro power,
So, all those energies are wind energy, and solar energy.
They may be able to apply to a larger scale.
technical challenges. sWhat you see here is energyy
storage devices.
is lithium batteries. They can hold a significant
amount of charge in a small size, and power devices
for computers, for laptops, and for cell phones, we all use
lithium batteries.
to have much higher power, but I think batteries are supposed
goes to micrometer scale, the energy stored in those batteries
becomes significantly small, so they're not powerful enough to
power small devices that we need
So right now, some people have to use in a micrometer scale.
three-dimensional micro battery, brought up some concept about a
here. aSo this device can reallyht
improve the capacity, but we're facing significant challenge of
fabrication.
structure. It's a very complicated
and technologists themselves So even though the scientists
maybe it's better for us to thharvest energy rather thane,
storing energy in such
So, now let's take a look at complicated structures.
that allows us to harvest. the energy out there
is solar energy, right here. The first one I see
a significant amount of energy Of course, outside at this size,
But if it's inside, you can see the indoor, the energy drops
down to six, which is five thousand times smaller
than outside. But the other types of energy,
for example, mechanical energy, vibration, acoustic, and even
the shoe insert, you can see
ten times higher than solar theenergy that's inside.out
Okay, so this means we have sufficient amount of source for
us to harvest as energy.
down here, 47, which means the Look at the battery coppacitors
us to get sufficient energy, engine source is sufficient for
that are being used right now. comparable to those batteries
going to harvest it, and where Now the question is, how are we
Actually, more than 20 year ago, does the energy come from?
called a human powered computer. IBM brought up this concept
compared the energy density to They did this calculation and
The picture on this chart shows the amount of energy from the
human body. Here we see the blood flow,
breath, exhalation, and movement, arms and fingers.
The energy density is around the
is walking. When you run you can reach about
100 watts.
Compare that energy to the small It's pretty significant energy.
here. All those devices require energy
in the micro-watt range.
can see, if we can make a device Compare the two values and we
efficient, we can still provide a sufficient amount of energy to
power small devices.
devices and put inside our It might be used for these
After this concept, progress has bodies.
First, I'd like to talk about the current technology for
harvesting energy from the human
Basically, these are on a larger body.
The first example I want to show scale.
walking. is energy harvesting from
sort of large device, you can This grsee right here.evice, a
This is the size of the device. They can put it on the knee.
This shows what is inside the device.
There are many gears. As we are walking around we move
the knee back and forth, and
gears inside. tThere is a little rotor righte
here. This electro-magnetic circuit
will generate electricity, an electro-magnetic effect.
This is the same concept as the windmill or as hydro-power.
It's just in a smaller size.
about five watts when people are It's really working and gives
It's quite a lot of energy and walking at a normal pace.
cell phones. can be used to power an MP3 or
size is quite big and I don't think it's that comfortable to
wear, right on the knee, just for 5 watts of energy.
This is just some progress that has been made in this type of
energy harvesting.
by MIT, Medialine. This is another technique, made
electro-magnetic effect. The same mechanism, the
heel, inside there are many Tgears to transfer the pressing
force into the rotation of the
electricity. gears rotor and generate
bit smaller, so it can produce This one is dense and a little
From these two examples you can see the magnetic effect really
can produce a lot of energy, but
realize this kind of complex it requires a large size to
Piezoelectric is another effect that many people have used to
harvest mechanical energy.
basically a crystal response to Piean external force.is
We know that many crystals are
ions distributed inside. formed by positive and negative
some force outside, the negatively charge ions are moved
away from the positively charged
The charge is displaced due to ions.
the crystals. the cBased on the differents in
directions in the change, we
side. This is called the piezoelecticr
effect. The electricity is a response to
the external pressure.
Here we show zinc oxide. Many crystals have this effect.
it's a hexagonal structure. Here is the blue sphere to show
zinc, which is positively charged and oxygen which is
negatively charged ions.
sitting inside of four oxygen Here tetragonal ions. ion
This is the equilibrium state.
this, we can shift this positive If we apply force on top of
create the polarization, a center away and that's how we
Based on this concept there are many materials that have the
same characteristics. For example, the PZT, a
contagnate, is a widely used
there are many other types of material that have these same
types of properties.
lead inside, basically. But allSo in terms ofls have
bio-compatibility, this is not
is a good response. gWhat we are looking at is this
zinc oxide, which is a bio-safe material, that is one essential
element in our human bodies.
can safely put inside our bodies, and also shows a good
response. The typical technique we use
with this material is called a
Basically, we can use the material and make a cantilever
and put a big mass on top of
Once the material experiences some external driving force the
cantilever will vibrate like
material, generating this and create a bending of the
The concept is kind of simple and therefore the set-up is
simple, the devices are simple. Here are some devices with the
piezoelectric cantilever. This is a quarter, so you can
make it smaller than a quarter. But you can see, the majority of
it is to produce the mass to
The cantilever is right here, it drive the cantilever.
The big volume is from this big mass to create the vibration.
We can use this device to generate 100 micro watts of
energy, to power some transistors.
Another type of material in addition to the ceramic
material is called a polymer, is a polymer-type material.
PVDF is one typical material. It has a very simple structure.
It has a carbon chain, right
right here. The hydrogen is positive and the
fluorine is negative. They arrange themselves like
this, and create a dibold,
Strain on this material will negative towards positive.
this material. create a dibold on two sides of
crystal structure. Same result, just different
flexible compared to the ceramic This polymer is much more
A lot of people have used this materials.
material in the energy material to replace ceramic
This is one example. harvesting area.
Army based project, to make a This is obackpack.nk it's an
Once you are walking and the bag
generates electricity. is moving up and down, it
electromagnetic effect. You have a rotor back here, and
it moves the rotor up and down
This device is very heavy. to generate the electricity.
19 watts but the maximum power Carrying the frame takes about
Doesn't make sense, right? is 7 watts.
to repress this, by putting it People who use the PVDF strive
That makes the weight much, much in the backpack.
milliwatts of power based on how less and it can still produce 60
The higher the load, the more much power is produced. bag.
Even though it produces less
It is a good improvement in poweusing this polymer basedess.
piezoelectric material for the
All right, so this is another example to show the use of PVDF.
It's a shoe insert. You can see, the shoe looks much
nicer compared to the previous
slides. So it just has a PVDF film put
inside the shoe, and the moving create the electricity to power
the small devices outside.
range of energy from this kind You can get in the milliwatt
At this point all we see is still on a larger scale.
You can see, on a millimeter or centimeter scale.
If we want to use this for
we want it much smaller. biomedical devices, of course,
The next topic that we're going to talk about is the
development of nanogenerators.
nano-sized material to replace The basic concept is to use
still realize this kind of the bulk sized material and
Of course we know the advantage of mechanical energy harvesting.
It's everywhere and can be
everywhere. harIt's accessible.om
We can find it inside rooms,
energy source is mechanical. outside, in the body our most
provides a lot of answers for a lot of biomedical implantabled
devices.
But the challenge right now, is that the larger devices we saw
previously, is the size.
very large. AIt creates a fatigue issue.e
The material has to vibrate many
fatiguing. times and it can become very
the need to integrate this large Because of the larger size and
some issue with the sensitivity masto small level mechanicale is
defamation. It also has to challenge, to be
adaptable to the micro-meter
Our solution is to use nanowires size of implantable devices.
materials. to replace those large size
structure that we see. Nanowires, this is one, the
and about 2 micrometers long. TThis size is 10 times smallerde
than the macro meter size devices.
This one we can really use
without changing the inside biological systems
The thing is, if we can use the piezoelectric material to make
this wire shape and create
polarization on two sides. defamation, we can also create
connect both sides, just like we If I can think about a way to
then we can create power from did fothis small devices.device,
It is easy to talk, but very
This is such a small size, about hard to realize.
The principle development was tdone in 2006, using a device.
called the atomic force microscopy.
Using this very small tip that
used as a metal tip, a metal is coated with a platinum and
the nanowatts. contact, and you'll see
growing on the side of the It's a very small size and it's
To use this small tip we can substrate.
small wires, and once we create cthe bending the conductive
atomic force microscopy tip will
and release a charge make contact with the nanowire
What you see on the chart down of nanowatts.
the nanowires you see right here is the chere. released from
Once the tip moves over those nanowires the charge is released
towards the tip.
We can really generate the This is a very exciting result.
wires. electricity from these small
connect all the devices that are So the next question is how to
equipment, and use it in an applicable device, right?
That's the second question to ask.
The intuitive thought for this
bending one nanowire at one one is, okaytime.re's one tip
How about if we can make an array of tips and move an array
of nanowires at one time. Or we can make a two dimensional
tip to bend an array of two dimensional nanowires to create
more power. Here is the concept and here is
the device. This is the first device that
we built in 2007. It still uses the nanowires and
a zig-zag electrode on top, sealed with a flexible spacer.
Okay? Then we create a vibration over
this device and the zig-zag electrode will create the
bending of the nanowires sitting
electricity in an beneaoutside circuit.reate
This is the concept and this is how we make it.
Based on the concept of the bending of the nanowires to
create electricity, we use the
density and then we integrate it vertical nanowires with less
with platinum as an electrode. with a silicon trench, coated
together, as we see right here. So put a zig-zag electrode on
top of nanowires. Or you can see the nanowires are
sitting beneath it. Most of them are in contact with
the electrodes. Then we can apply external
vibrations towards this device, so the nanowires inside will be
bent from the vibrating, and
the outside circuit based on the will create electricity toward
This is the first generation of nanogenerators.
Another aspect that I want to talk about here is encoding on
the nanowires.
contact. It's called the Schottky type of
come from only one way, instead That of from the other.s can
The electrons can only grow from
nanowires based on the the electrode towards the
This will generate DC output piezoelectric effect.
Once we've applied a sonic wave toward device, we can see the
current output is a DC type of
device. Here is an IV curve that has
been measured based on this device and you can see that the
maximum voltage we can produce
The maximum current we can is about 10 millivolts.
square centimeter. produce is one microamp per
can run the device with the Thimaximum output of power.we
Based on this first generation
maximum output energy, about 10 nanowatt per square centimeter.
It's still very small, okay?
2.5 nanowatt per square The operacentimeter.r is about
So this is a very small amount
expectation. of energy and much less than our
are not really doing their jobs. All the nanowires, seemingly,
we could get a microwatt output. If everyone is doing their job,
challenge on such a small scale. Fabrication is still the
many improvements for this kind The researcof device.s work did
He used nice -- techniques and
between the array of electrodes. put nanowires laterally in
devices you see right here. On top of this is an array of
nanowire devices you see here inside.
Based on this device you can
nanowire contacts with an electrode, and each nanowire is
doing it's job. There is a significant amount of
power out of this device. The output is about 40
millivolts and the power is nearly a milliwatt, at least 10
to 100 microwatts.
use this device to power a PH This chart sensor. here, they
You can see this different
value. response to show different PH
to show that this nanogenerator Tdevice can be used for somet
electronic devices. So this is pretty recent
progress done by the Georgia
from. Now probably many people have
the question, how much power can
of device? really be provided by this kind
many times. I've Here is the answer.stion
We did this calculation about two years ago.
Of course we know, based on,
I won't go through that- this equation that I developed,
larger the size of the nanowatt, Intuitively we can see, the
And the smaller the wire, the less mechanical energy that we
need to bend that nanowire. So there is a trade-off between
these two.
few volts with this nanowire, Tbut in terms of power, this is
what one nanowire can produce in
This is the diameter, and this terms of power and efficiency.
You can see, basically, the larger the size of nanowire, the
more power that it can produce
energy input. butIf the power is high, theical
efficiency is very low. If we have very small wire,
efficiency can be very high, but
So there is an optimal point, right here at this point, where
we can achieve reasonable good
efficiency. This is at the size of about
three micrometers long and 50 to
those nanowires. 100 nanometers in diameter for
per nanowire, and the efficiency We can reach about .1 nanowatt
Based on this calculation we can is about 4%.
give us a sufficient amount of see, okay, this one can really
many nanowatts together. energy if we can integrate many,
made in the next devices. TSo what is the applicatione
potential for this device?
see right here. In 2In 2007, after the firstl to
development of this concept, -- Think of this as research that
benefits the nation.
congress. ThA year later there waso
Scientific America, they
project this application of this published this article to
This is a conceptual device, nanogenerator.
This is actually a blood vessel. made by nanowires.
The change of blood pressure can These are red cells inside.
this capacitor and then charge generate the power to charge
blood sugar level or blood this remote sensor to sense the
inside of the blood vessels. pressure, or all sorts of things
conceptual article published in AlScientific American.a
So there are some real
Recently, that also has been developments.
There are several developments. This is a nano, small generator,
you'll see, put on top of the finger.
Remember in the first, previous slides we showed, moving the
finger can generate microwatt energy.
It's put on top of the finger and it will produce mini volt
voltage output. Okay?
So this is a pretty significant output compared to the
vibrational nanogenerator.
nanogenerator on top of this And they also put this
So the hamster running inside it's little cage can generate
electricity.
This one? [i>> Yes.e]
This is a National Scientific Foundation, financial year 2008.
The budget request to congress.
The hamster is running and
stops, there's not output. producing voltage and once it
producing electricity. It's basically muscle movement
an extreme example. TThey put this nanogenerator on
top of a heart, I think it's
Then the heart beating produces electricity as well.
That's why I kind of brought it up, sorry.
It does show some application of
integrating with biological this nasystems.tor and
Another development is called Power Fiber, done back in 2008.
This is another concept for harvesting energy from human
motion. The basic concept is, we
integrate those nanogenerators
our cloths. The concept is that we have this
fiber and we will grow the
Some fibers are coated with gold nanowire on those fibers.
Some fibers are just pure to act nanowire.ctrode.
We wire these two types of
Then if there's any relative fibers together.
fibers, those nanowires can create defamation of those
nanowires, and then we can
This is what we call Power produce electricity.
lot of attention once the paper Fibepublished, and is alsoed a
recognized by the National
second report to congress. Nanotechnology Initiative, the
development on the cover to show So they highlighted this
harvesting. Of course the development is
still way far from the closest
The first proof of concept is just two fibers, one with gold
and one without, just entangle
Then we create movement between those two fibers.
The other concept is still the
We have this gold coated wires same.
They are moving relevant to this as electrodes.
Once they move, the nanowire zinc-oxide nanowire.
it will create electricity and beneath it will be deflected and
nanowire with metal coating. it will be harvested by the
does take a lot of effort to The concept is the same, but it
This is the Kevlar fiber that the Army uses to make
bulletproof jackets.
what we see on top, is It's one fiber with micro size,
around it. zinc-oxide nanowires growing
you can see. It's a very uniform coating as
solution based technique. You put the fibers in a liquid
and after about a day, take it
like this. out and you'll see something
manufacturing technique just It's basically a larger scale
It's a similar process. But now we can achieve lots of
nanowires growing like this.
between those nanowires as well. There are a lot of spaces left
gold on one side, and some wires So we coat those nanowires with
Then we also develop a are just bare.
nanowires around those fibers to technique to tightly seal those
fall off. On this image you can see tow
fibers tangled around.
gold, and the whiter one is The coated with zinc-oxide.oated
So you move them around and you can create a very small amount
of electricity. It's about five picoamps, a
thousand times smaller that ultrasonic generators, and the
voltage is small as well. The key problem is the
resistivity of the fiber is very
There's a huge loss when the huge.
nanowire towards the end. elAlso the contact area isch
limited.
Here we put six fibers together Weinstead of two.th.
Of course that improved the contact area, and you can see
the current output increased
We also improved the nearly 100 times.
conduct layer beneath conductthe nanowire.ing the
By doing this we increase the current by 1,000 times, from
four picoamps to four nanoamps. We also showed the current to
output relationship with the
The thing is, if we just need to resistivity of the fiber.
we can get a majority charge out make the fiber conductive then
This is a very exciting of improvement.s.
The last part I want to talk
that we did here at UW-Madison about is a recent development,
polymer microbelt to harvest last year using a piezoelectric
breath. enerBasically this kind ofrom
development is to harvest energy
So, everyone knows, wind, harvesting energy from air flow
and we have windmills.
much smaller scale. BWe can't put such a big device
inside our nose.
It won't work. That sounds weird.
And the larger scale wind energy You want something different.
small scale. harvesting will not work in a
cut-off wind speed. IThe wind has to be above ad
certain level to drive this device.
If it's smaller then it won't work.
Once I had this idea, I saw another development from another
company.
They make a belt like this and They call it a windbelt.
magnetic bar. This magnetic bar sits inside a
copper coil, just an
The vibrations of beam will create a vibration of this
magnetic bar inside the coil
So they can make it in a small and generate electricity.
This is a very small scale, and this is a larger scale that they
make and put outside of the building.
It can create, like, a milliwatt
the building. I think that's one device they
put in Hong Kong, or Singapore. Yes.
[inaudible]
Mostly because of friction
rotor here. insBased on this concept,big
we can make it even smaller.
electromagnetic effect we can't reduce the device further.
You have to have a significant
circuit to generate power. amount of currant go though this
piezoelectric to replace the So here our concept is to use
just by vibrations and remove beltthe rest of the parts.ity
First of all, I'm sorry about this.
I use PC and this is a MAC so we
Anyway, this is not important. have some conversion problems.
in order to create the We did this calculation to show,
to have the right size. vibWe have to have the rightave
thickness and the right length, or the right ratio.
You want to make the belt vibrate in a small wind.
This is our calculation.
drops so we can create a higher Yoamplitude of vibration ands
generate a high power, the more important then airflow speed.
The smallest thickness, it will show some response at a very
slow airflow speed. For the larger thickness there
won't have any response, because
driven by those kind of wind the vibrations will not be
This is our output prediction, speeds.
produce about a microwatt level of energy based on the airflow
that is less than one meter per second with the thickness in the
micrometer size range.
using the PVDF as a polymer. Okay, so based on this, we're
material I showed you That's thepreviously.ric polymer
It's used for this development. One key change for us is that we
cannot make this device very
the PVDF material has small,different phases.se for
This is the phase that we want.
We want all the hydrogen to stay
stay on the other side. This is a high energy phase, and
it will not happen until we apply a very high strain on this
material. This means we cannot make it
very thin.
not survive under high strain. If we make it very thin it will
We won't know while we are at this kind of phase.
So we tried different ways and
with a thick material in the we found out that we can start
piezoelectric phase. beta phase, which is a
technique. We are using a top-down action
towards the material to blow An ion bean action to shoot ions
thinner. away material and make it
thickness from 25 to almost 10 This way we can reduce the
This is within the range that we micrometers.
significant amount of power under very slow wind flow.
We also are very excited to find
will keep the phase unchanged. out that this kind of technique
show this peak right here, and We did this FTL measurement to
characteristic peak of the beta this peak phase.here, is a
We are very glad to see that
long term action and we can make this beta phase exists over the
We are very happy to see that. it very thin.
because of the MAC computer. I apologize about this too,
This is the device itself. So, you can look at this.
right here. We coat it in gold, the electron
on top, and the other coated
We've got this change. electron bottom.
micrometers thick. The belt itself is about 15
voltage meter. Then connect this end to the
Once blow air through this small We can see, this is that output.
different wind speeds. belt, we can see output on the
can still see some voltage Even at a very low wind speed we
millivolts at a slow wind speed. generation from about 10
that we see. So this is very good improvement
with different thicknesses and We made different assemblies
and this is the in power. Of course, with the reducing of
airflow speed the voltage drops quickly and the power drops
quickly as well.
at here is this. One thing we want to take a look
the voltage increases at a slow Once we airflow rate.hickness
This is a good part that I
We reduced the thickness and really like to see.
That's why we want to use it to inharvest energy from thet.
respiration.
calculate the power, the is around a microwatt range to a
10 nanowatt range using a single belt.
Then we are starting to see how much energy can really be stored
by this device. We then integrated the device
with a capacitor, a simple
We can see, the charge of the battery is increasing in voltage
measured on the battery.
wind speed, of course, the more energy that can be stored on the
capacitor.
balance of the charging rate and This is just because of the
the capacitor. the leaking rate of
believe we can achieve better With a bestorage.acitor I
But just based on this capacitor
around a 100 microjoules to we1,000 microjoules based one
different airflow speed.
many small electronic devices. This energy is sufficient for
stopwatch. For example, a lab-based
generator. We hook up a stopwatch with this
I hope it will work. Here's a video you can see.
here, we took the battery out of In the video, you see right
up these two wires with our this stopwmicrobelt.imply hook
Then we have airflow through
Now you can see the belt right here.
watch is starting to show. starting to vibrate and the
We can actually operate it If we block it, it disappears.
the screen. normaIt's a little longer.howing
So we can press a button and do the normal functions.
Of course the response take a little bit longer than a normal
battery, but it shows that it works very well based on this
small belt. I apologize again for this.
It was a good picture.
So we are starting to use this I liked it.
respiration. energy harvesting from
the nose. OfWe made it as a simulatedin
device. We made a little tube, a very
small tube. Then we put our belt inside the
tube and the other end it is
So expansion and compression, to connected to a lung simulator.
the respiration. pump airflow through to simulate
rate of normal human On this chart is a normal flow
It's basically a sin curve. The maximum speed of airflow
from normal respiration is
So of course, if we have the about two meters per second.
wind speed, then more energy belt that has a slow cut off
respiration. will be harvested from this
with about 15 micrometer We used the belt that we made
with this belt. Through this we can see thed
voltage generation from the belt
Connect it with the capacitor, based on the breath.
operation we can store the after about ten minutes of
about a 200 millivolts and the charge and the voltage can be
This is enough for most chargeelectronic devices.joules.
OF course, right now, if you
nose, I don't know. asked me h[laughter]this in a
Here I just show that there is a
able to make into a small size material that is available to be
small flow-rate from human and harvest energy from such a
This is a prospect of this breath.
kinds that we see. nanogenerator, the different
mechanical energy into Nanogenerators can convert
And around us there are many electricity on a small scale.
small scale to large scale. meFrom breath, as in the one Im
just showed, and blood flow or
On a large scale, from the wind, heartbeat.
car running or even some random tvibration inside a building,a
such as air conditioning of from
the floor. some acoustic waves on
source for this nanogenerator Ato power this and generatea
electricity.
we use we can use it for Based on different sources that
pacemaker, for this kind of implantaenergy source.uch as a
And we can use it for some
lighting sensors. dLike the ones put in enemy
territories, where no one can be
Or robots that needs to run by able to replace the batteries.
Also some names of nano-devices. itself.
been realized. Of course this one has already
amount of energy, then I hope that someday we can use it tot
power small personal electronics
Then we will not need to carry based on this techniques.
This basically concludes my the chargertalk.nd with us.
My last slide is
I thank my group, my young acknowledgement.
This is my third year here and group.
students and a previous my post-doc, and some fundingte
support from NSF and -- and also
graduate school and --. sThere was also some work thatW
was done at my previous school, at Georgia Tech -- Group before
I came here.
Thank you very much. All right.
[applause]