Nanoribbons Nanotechnology

PRESENTED BY

RAJKUMAR.G [email protected] 9952570376

EEE Department, I year B.E.A.C.C.E.T.,

Karaikudi – 4.

NANORIBBONS - NANOTECHNOLOGY

mailto:[email protected]

ABSTRACT:

Developing new methods for integrating highly efficient energy transformation

systems onto stretchable rubbers which are compatible with human body, could lead to path-

breaking innovations in the field of wearable and also implantable energy harvesting systems. This

Paper suggests one such innovative method for energy optimization-- the idea of “Embedding

Nanoribbons of a Piezoelectric crystal on highly elastic rubber Polymers”. Piezo-force

microscopy of the nanoribbons shows that the piezo crystal facilitates maximum energy conversion

only on a flexible medium, such as rubber, which is why this technique proves to be a promising

one. The best piezoelectric material known, Lead Zirconate Titanate (PZT) is first taken in the form

of a ribbon (of the scale of a few nanometers) and then this nanoribbon of the piezo material is

embedded on flexible rubber polymers, so as to produce energy continually as it is flexed. The

excellent performance of the piezo-ribbon assemblies coupled with stretchable, biocompatible

rubber may enable a host of exciting avenues in fundamental research and novel applications.

NANORIBBONS - NANOTECHNOLOGY

Nanoribbons - Nanotechnology

I. INTRODUCTION

In what appears to be the latest development

in nanotechnology, nano sized ribbons of piezoelectric

crystals are all set to change the very way we work.

Imagine your car’s battery power getting refilled by

the very distance you travel, or pacemakers running

due to the patient’s breathing, instead of artificial

batteries. These are just primitive examples of one of

the most promising developments in nanoscience-

NanoRibbons.

Piezoelectric materials are the best known

energy converting materials. Nanoribbons of these

materials embedded onto flexible rubber produce

much more efficient piezo materials with ultimately

high energy converting capacities.

II. TERMINOLOGY

Energy Conversion: Energy in a system may be

transformed so that it resides in a different state.

Piezoelectricity: Piezoelectricity is the

charge which accumulates in certain solid in

response to applied mechanical strain.

Nanoribbon: A nanostructure in the form

of a ribbon.

Piezoelectric Force Microscopy (PFM): A new

scanning probe microscopy mode that utilizes the

piezoelectric effect of materials to generate

contrast.

Flexible electronics: A technology for

assembling electronic circuits by mounting

electronic devices in flexible plastic substrates.

III. THE PIEZOELECTRIC CRYSTAL

Piezoelectricity means “it generates an

electrical voltage when pressure is applied to it”.

Piezoelectric crystals are one of many small scale


energy sources. Whenever piezoelectric crystals are

mechanically deformed or subject to vibration they

generate a small voltage, commonly known as

piezoelectricity. This form of renewable energy is not

ideally suited to an industrial situation.

Being electromechanically coupled,

piezoelectric crystals function as sensors/actuators,

and energy converters. Yet, the crystallization of these

materials generally requires high temperatures for

maximally efficient performance, rendering them

incompatible with temperature-sensitive plastics and

rubbers. This can be surpassed only means of using

nanoribbons.

Lead zirconate titanate (PZT). This is a

ceramic material that is piezoelectric. Thus when

pressure is applied to it, an electric voltage can be

generated by this material.

It is said that of all the piezoelectric materials in

existence so far, PZT is the most efficient.

Apparently it is 100 times more efficient than quartz

which is another piezoelectric material.

When a person is walking or breathing not

a whole lot of power is generated. So it is important

that a high percentage of it is converted.

IV. ROLE OF NANORIBBONS

Nano sized ribbons are extracted from the PZT material and embedded on suitable rubber materials. These nanoribbons, or strips of nanotubes are extremely thin that 100 of them can fit side-by-side in a space of a millimeter.

By this method we can successfully combine silicone and nanoribbons of lead zirconate titanate (PZT), a ceramic material that is piezoelectric, meaning it generates an electrical voltage when pressure is applied to it. Of all piezoelectric materials, PZT is the most efficient, able to convert 80 percent of the mechanical energy applied to it into electrical energy.

V. FABRICATION


First step of Fabrication is producing PZT nanoribbons -- strips so narrow that 100 fit side-by-side in a space of a millimeter. In a separate process the strips are embedded into clear sheets of silicone rubber. Silicone, which is used for cosmetic implants and medical devices, already is biocompatible.

PZT films are grown on a cleaved magnesium oxide crystal substrate and post annealed to form a perovskite crystal structure. Second, the structure, composition, and piezoelectric response of the films are characterized to ensure optimal performance. Next, the films are patterned into nanothick ribbons and printed onto clear sheets of silicone rubber (PDMS) via dry transfer. Finally, the fundamental piezoelectric properties are characterized on the rubber substrate using a nanoscale characterization method, piezoresponse force microscopy.

Growth conditions for ceramic crystals are critical for achieving high piezoelectric performance – high temperatures and a carefully chosen growth substrate are required – both incompatible with flexible rubbers or plastics.

Next, the fabricated PZT Nanoribbons are printed onto silicone rubber. The sheets are embedded with nanoribbons of lead zirconate titanate (PZT). But PZT is crystalline, and its synthesis requires high temperatures that would normally melt a flexible substrate.

This problem can be overcome by treating the PZT in a chemical etching bath to remove a thin nano-sized ribbon from the surface of the crystal. A polymer stamp then transfers the ribbon onto a silicon sheet, which is then encapsulated with a second sheet and sealed. The overall process does not reduce the PZT's efficiency.

Top: The process piezoelectric nanoribbons are peeled

off a host substrate and placed onto rubber. Middle:

Photograph of the piezo-rubber chip. Bottom:

Schematic image of the energy harvesting circuit.


VI. WORKING

A rigorous thermodynamic treatment shows

that bending of these nanoribbons can be primarily

attributed to the coupling between piezoelectric

effects, electric polarization, and the motion of free

charge originating from point defects and dopants.

The present theory explains the following

experimental observations: the magnitude and sign of

curvature and how this curvature depends on film

thickness and dopant concentration. Good agreement

between theory and experiment is obtained with no

adjustable parameters. We identify three regimes of

bending behavior with distinct thickness dependence

for bending radius that depend on free carrier density,

film thickness, and elastic, piezoelectric and dielectric

constants.

The material consists of silicone rubber

sheets and ceramic nanoribbons (nanostructures or

nanotubes that take the form of thin ribbons) are

embedded in it. When this material is flexed it is

capable of generating electricity. It is highly efficient

at converting mechanical energy in to electrical

energy- Up to 80%.

VII. APPLICATIONS

The human body is a ideal source of power

if we can harness our body motion such as walking,

finger typing or breathing. This would be especially

convenient for implantable medical devices such as

pacemakers, since surgeries are now required to

replace dead batteries. If we could replace those

batteries with power directly harvested from the

continual motion of the lungs, it could significantly

improve the quality of life for patients.

Potentials for this new material:

1. Shoes made of these rubber sheets can potentially

harness the energy of walking and running to power

mobile electronic devices like mobile phones and MP3

players.

2. Even more significant is that when placed against

the lungs, these sheets could harness the breathing

motions to power pacemakers, eliminating the current

need for surgical replacement of batteries.

3. In the future, the simple acts of breathing and

walking can power electric devices through nanoribbons

so small they could even be implanted in the body,

turning humans into the ultimate green battery.


Pacemaker owners all over the world and

other people in need of a reliable, small current source

will surely be glad to know about this piezoelectric

energy conversion system.

The material is composed of nanoribbons

embedded onto silicon sheets, and it generates

electricity when flexed. The new flexible piezoelectric

material could make up shoes or clothes, charging

your music player or whatever else. Also, being

embedded in silicon, the material can be implanted in

one’s lungs, for example, to harvest the electricity

needed by their pacemakers, thus eliminating the need

of surgically changeable batteries.

The biocompatible material could be

placed next to a person's lungs and utilize breathing

motions to power pacemakers. That could reduce the

need for surgery to replace batteries in the device.

The devices are initially targeted for use

in medical applications — for example, pacemakers,

where the movement of a person breathing would

generate enough electricity. (Today's pacemakers run

on batteries, and people have to undergo surgery in

order to replace them.) But, the devices are scalable

— larger sheets can power personal electronics like

mobile phones, and even larger ones can convert the

movements of a car's suspension to replenish battery

power.

VIII.ADVANTAGES

In addition to generating electricity when it is flexed, the opposite is true: The material flexes when electrical current is applied to it. This opens the door to other kinds of applications, such as use for microsurgical devices.

The new electricity-harvesting devices could be implanted in the body to perpetually power medical devices, and the body wouldn’t reject them.

Main advantage is that it is scalable. As these chips are made more perfect, larger sheets can be manufactured to harvest more energy.

Silicone is a biocompatible device. i.e. it is a material that can replace part of a living system or function in close contact with living tissue. Silicone is already used for cosmetic implants and medical devices. Thus the new power generating rubber sheets are also biocompatible.


IX. DISADVANTAGE

Like all other gadgets that can be powered by kinetic energy (including the Dance Charge, which is strapped around the arm and powered, as the name suggests, by dancing) still, it is hard to significantly power devices through movement alone.

X. CONCLUSION

No one can afford to ignore the dramatic developments that nanoribbon technology is producing in materials and the manner in which materials are designed and manufactured. It helps to improve products and production processes with better characteristics or new functionalities. In the coming years, products based on nanoribbons will impact nearly all industrial sectors and enter consumer markets in large quantities.

These developments if given proper scope, have the potential to radically alter every aspect of our life from charging our cellphones to performing the most complex of operations and surgeries. Moreover, this utilizes the energy produced from within. So it is also basically cost effective. Considering the medical aspects, this has a long way to go beyond powering pacemakers and facilitating microsurgeries.

XI. REFERENCES

Applications of Nanotechnology by Professor Ravindra K Dhir, Dr Moray D Newlands

www.nanowerk.com

Semiconductor Nanowires And Nanoribbons by Xiangfeng Duan


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Nanoribbons Nanotechnology