Nanogenerator's output triples previous record

Jan 03, 2013 by Lisa Zyga feature
(Top) The nanogenerator produces a voltage under a periodic mechanical deformation. In the deformed nanogenerator, the red and blue regions indicate a positive and negative piezoelectric potential, respectively. (Bottom) Optical photographs of the nanowire array showing its flexibility and robustness. Credit: Long Gu, et al. ©2012 American Chemical Society

(Phys.org)—Taking an important step forward for self-powered systems, researchers have built a nanogenerator with an ultrahigh output voltage of 209 V, which is 3.6 times higher than the previous record of 58 V. The nanogenerator, which has an area of less than 1 cm2, can instantly power a commercial LED and could have a wide variety of applications, such as providing a way to power objects in the "Internet of Things."

The researchers, led by Yong Qin at Lanzhou University in Lanzhou, China, and the Chinese Academy of Sciences in Beijing; and Zhong Lin Wang of the and the Georgia Institute of Technology in the US, have published their study on the new nanogenerator in a recent issue of .

The nanogenerator consists of an array of vertically aligned 420-μm-long nanowires, with on the top and bottom of the array. Under the periodic impact of an object weighing about half a pound, or simply the press of a finger, the nanogenerator experiences a pressure that causes the nanowire array to deform. Due to the , this mechanical compression drives toward the bottom electrode, generating an electric current. When the heavy object is removed, the pressure is released and the electrons flow back through the circuit. By repeating this periodic mechanical deformation on the nanogenerator, the researchers could generate electricity.

This video is not supported by your browser at this time.
The impact of a finger can cause the nanogenerator to produce sufficient current to stimulate a frog’s sciatic nerve, which causes the frog’s gastrocnemius muscle to contract, moving the frog’s leg. Video credit: Long Gu, et al. ©2012 American Chemical Society

The scientists found that the amount of electricity generated by the nanogenerator depends on the impact force. By dropping an object with a weight of 193 grams onto the nanogenerator from different heights ranging from 5 to 13 mm, the scientists observed that the is proportional to the square root of the falling height.

In their experiments, the researchers demonstrated that a large enough applied to the nanogenerator can generate a peak voltage of 209 V and a peak current of 53 μA, corresponding to a current density of 23.5 μA/cm2, which is 2.9 times higher than the previous record output of 8.13 μA/cm2.

"The power output of a nanogenerator depends on voltage and current, because the is the product of the voltage and current," Wang told Phys.org. "By raising the , we naturally raised the output power. This is essential for any and all applications for driving small electronics, portable electronics and wireless sensors."

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Video showing the full set-up of the nanogenerator connected to an LED, a close-up of the LED, and the LED light shining in synchrony with the nanogenerator’s pulsing electric signals. Video credit: Long Gu, et al. ©2012 American Chemical Society

The researchers showed that the power output achieved here is high enough to directly power a commercial 1.9 V LED. Unlike most other nanogenerators, the new device does not require an energy storage unit, an advantage that can enable self-powered systems to operate in a wide variety of environments.

Besides powering an LED, the nanogenerator may also have biological applications. Here, the researchers used the nanogenerator to stimulate a frog's sciatic nerve and cause the frog's gastrocnemius calf muscle to contract. Previously, this phenomenon has been demonstrated using a large nanogenerator with an area of about 9 cm2, whereas the new nanogenerator with an area of just 0.95 cm2 can perform the same nerve stimulation and induce muscle movement under the small impact of a tiny finger tap.

In the future, tiny high-power nanogenerators like this one could have applications in repairing biological neural networks, in national security, and in the "Internet of Things." In this last scenario, all physical objects would be tagged (such as with radio frequency identification [RFID]), and virtually represented in a future Internet, where they could be monitored in real time.

"The future plan is to continually raise the output power so that we can meet more technological needs," Wang said.

Explore further: World's smallest propeller could be used for microscopic medicine

More information: Long Gu, et al. "Flexible Fiber Nanogenerator with 209 V Output Voltage Directly Powers a Light-Emitting Diode." Nano Letters. DOI: 10.1021/nl303539c

Journal reference: Nano Letters search and more info website

4.7 /5 (13 votes)

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User comments : 19

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MrGrynch
3 / 5 (6) Jan 03, 2013
How sick is that twitching frog leg?!?! Yay science
phillip_hooper2
4.7 / 5 (3) Jan 03, 2013
This should be placed on the inner lining of electric car tires, constantly generating voltage with no new net loss due to additional friction. Outstanding
Lurker2358
2.4 / 5 (5) Jan 03, 2013
It does seem more useful in cybernetics.

RealScience
4.8 / 5 (4) Jan 03, 2013
@phillip_hooper - Flexing the material takes mechanical energy. If one extracts electrical energy then one gets less 'rebound' than the force it took to flex the material.

There are cases where you want to dissipate energy anyway, such as a shock absorber. In such cases you could get a net energy gain (however it might not be worth the cost).

TheKnowItAll
5 / 5 (2) Jan 03, 2013
I'm curious as to what happens if you instead apply a voltage to it.
packrat
2.4 / 5 (5) Jan 03, 2013
Now create a long strip of it and make one of those vibrating wind energy devices some guy built a couple of years ago. It could generate both from the little magnet/ coil arrangement originally used and from the fluttering ribbon itself at the same time. Between the two different sources it might just make a decent little wind power generator.
Sean_W
3 / 5 (6) Jan 03, 2013
I'm curious as to what happens if you instead apply a voltage to it.


There are materials which work both ways (movement to voltage or voltage to movement). I don't know for sure if this one does but it wouldn't surprise me. Whether it is as impressive in reverse is another question.
Claudius
2 / 5 (6) Jan 03, 2013
One wonders what national security applications this will have.
antialias_physorg
5 / 5 (1) Jan 04, 2013
There are cases where you want to dissipate energy anyway, such as a shock absorber. In such cases you could get a net energy gain (however it might not be worth the cost).

I really wish there was enough energy in the backround seismological activity of the Earth's crust.
I once went to the german national institute for seismology and talked with them about it (when the first reports on these types of nanogenerators came out about 3 years ago. They were caught a bit off guard since they never look at the background data but only ever at the sizeable earthquake events. So getting good datasets took a bit of doing).

Unfortunately the energy density is too low to make this economically viable (maybe in regions with elevated background activity - like around volcanoes - or deep underground in abandoned mine shafts).

Darn shame. Would have been a truly sustainable and eco-friendly power source (and earthquake-safe. Ha!).
antialias_physorg
5 / 5 (2) Jan 04, 2013
I'm curious as to what happens if you instead apply a voltage to it.

It's piezoelectric (which is a reversible process) - so when you apply a voltage the material does the same (it bends).

Ultrasound systems work that way (applying a voltage to a piezoelectric material which deforms and thereby creates a shockwave). Also used for extremly precise positioning needs (hard drives head dampening systems) and cretaing small openings (ink jet printer nozzles, etc.)

On a weird note: collagen in the body is mildly piezoelectric.
Whydening Gyre
1 / 5 (4) Jan 04, 2013
"Diamonds" in the soles of her shoes...
For people who walk a lot this could be a nifty power source. Someone who plays drums could damn near start charging...:-) Or in the spokes of bicycles with a card attached so the card "slaps" each spoke... Or in the head of a hammer so you could then charge your power screwdriver...
Or in tooth caps - gum manufacturers would be FILTHY rich...
The ubiquity of this is mind boggling...
Whydening Gyre
1 / 5 (3) Jan 04, 2013
On a weird note: collagen in the body is mildly piezoelectric.


Now THAT I found interesting... Slapping someone on the butt creates energy... hmmm.
RealScience
not rated yet Jan 04, 2013
There are cases where you want to dissipate energy anyway, such as a shock absorber. In such cases you could get a net energy gain (however it might not be worth the cost).

I really wish there was enough energy in the backround seismological activity of the Earth's crust.


The background seismic activity has very low power density - the ground does not shake or vibrate under our feet.

The first comment quoted above was a response to:
This should be placed on the inner lining of electric car tires
So I was referring to car shock absorbers (and questioning whether the power density would be enough to be worthwhile even there).
antialias_physorg
5 / 5 (1) Jan 04, 2013
The background seismic activity has very low power density - the ground does not shake or vibrate under our feet.

It does - constantly. The amplitude is just very low.

The power is actually there (not nearly to the degree of solar, but 24/7 and everywhere. IIRC the magnitude was something like 0.1W per square meter).
The problem is that you'd have to tune the geometry of your nanogenerator to a specific frequency. And when you do a fourier decomposition on the seismic background (power spectrum) it turns out that there aren't any good peaks. So the power you could harvest with one of these would be only a fraction of the power in the seismic background.

Oh well - it was a fun idea while it lasted back then.
tkjtkj
not rated yet Jan 06, 2013
".."The power output of a nanogenerator depends on voltage and current, because the output power is the product of the voltage and current," Wang told Phys.org. "By raising the output voltage, we naturally raised the output power. This is essential for any and all applications for driving small electronics, portable electronics and wireless sensors."

Perhaps .. not always: Eg, if V is doubled, but I is halved: no net gain ..
Whydening Gyre
1 / 5 (3) Jan 06, 2013
".."The power output of a nanogenerator depends on voltage and current, because the output power is the product of the voltage and current," Wang told Phys.org. "By raising the output voltage, we naturally raised the output power. This is essential for any and all applications for driving small electronics, portable electronics and wireless sensors."

Perhaps .. not always: Eg, if V is doubled, but I is halved: no net gain ..

But, current is relative to the amount of work being done... Increase the resistance(R) to the potential(V) and current(I) goes up...
So, I think the article/study inference is that with an increase in V, while keeping R constant, you get an increase in I.
Q-Star
1.8 / 5 (5) Jan 06, 2013
with an increase in V, while keeping R constant, you get an increase in I.


I'm thinking you have that backwards, an increase in voltage will get you a decrease in current, if the resistance is held constant. But what did Mr. Ohms know?
Q-Star
2 / 5 (4) Jan 06, 2013
with an increase in V, while keeping R constant, you get an increase in I.


I'm thinking you have that backwards, an increase in voltage will get you a decrease in current, if the resistance is held constant. But what did Mr. Ohms know?


Apparently more than I do,,,,, I stand corrected,,,,,
Whydening Gyre
1 / 5 (2) Jan 07, 2013
with an increase in V, while keeping R constant, you get an increase in I.


I'm thinking you have that backwards, an increase in voltage will get you a decrease in current, if the resistance is held constant. But what did Mr. Ohms know?


Apparently more than I do,,,,, I stand corrected,,,,,

That almost sounds like a retraction, but don't be so hasty.:-)
Ohm says that I=V/R. By that equation, you are thus correct. I am over 50 so my memory of my old days in electronics can get a little hazy (at least give me that).
What I meant to say was that the if Potential (V) is increased the efficiency of work done (I) is higher given a constant resistance. Current is doing the same work, but with less effort, proportionally speaking. My bad...