nanoribbons nanotechnology
DESCRIPTION
nano technologyTRANSCRIPT
PRESENTED BY
RAJKUMAR.G [email protected] 9952570376
EEE Department, I year B.E.A.C.C.E.T.,
Karaikudi – 4.
NANORIBBONS - NANOTECHNOLOGY
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
Nanoribbons - Nanotechnology
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
Nanoribbons - Nanotechnology
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.
Nanoribbons - Nanotechnology
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.
Nanoribbons - Nanotechnology
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.
Nanoribbons - Nanotechnology
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
Nanoribbons - Nanotechnology