report on bio nano generators

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REPORT REPORT PRESENTED TO PRESENTED TO : M. WAQAS ALI M. WAQAS ALI PRESENTED BY PRESENTED BY : HIRA RASAB HIRA RASAB (SP08-BTE-022) (SP08-BTE-022)

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REPORTREPORT

PRESENTED TOPRESENTED TO::

M. WAQAS ALIM. WAQAS ALI

PRESENTED BYPRESENTED BY::

HIRA RASABHIRA RASAB

(SP08-BTE-022)(SP08-BTE-022)

YUSRA FAROOQYUSRA FAROOQ

(SP08-BTE-060)(SP08-BTE-060)

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NANOTECHNOLOGY

“Nanotechnology, shortened to "nanotech", is the study of the controlling of matter on an atomic and molecular scale.”

Generally nanotechnology deals with structures of the size 100 nanometers or smaller in at least one dimension, and involves developing materials or devices within that size. Nanotechnology is very diverse, ranging from extensions of conventional device physics to completely new approaches based upon molecular self-assembly, from developing new materials with dimensions on the nanoscale to investigating whether we can directly control matter on the atomic scale.

There has been much debate on the future implications of nanotechnology. Nanotechnology has the potential to create many new materials and devices with a vast range of applications, such as in medicine, electronics and energy production. On the other hand, nanotechnology raises many of the same issues as with any introduction of new technology, including concerns about the toxicity and environmental impact of nanomaterials, and their potential effects on global economics, as well as speculation about various doomsday scenarios. These concerns have led to a debate among advocacy groups and governments on whether special regulation of nanotechnology is warranted.

History of Nanotechnology

The first use of the concepts found in 'nano-technology' (but pre-dating use of that name) was in "There's Plenty of Room at the Bottom," a talk given by physicist Richard Feynman at an American Physical Society meeting at Caltech on December 29, 1959.

Feynman described a process by which the ability to manipulate individual atoms and molecules might be developed, using one set of precise tools to build and operate another proportionally smaller set, and so on down to the needed scale.

In the course of this, he noted, scaling issues would arise from the changing magnitude of various physical phenomena: gravity would become less important, surface tension and van der Waals attraction would become increasingly more significant, etc. This basic idea appeared plausible, and exponential assembly enhances it with parallelism to produce a useful quantity of end products.

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The term "nanotechnology" was defined by Tokyo Science University Professor Norio Taniguchi in a 1974 paper as follows:

" 'Nano-technology' mainly consists of the processing of, separation, consolidation, and deformation of materials by one atom or by one molecule."

In the 1980s the basic idea of this definition was explored in much more depth by Dr. K. Eric Drexler, who promoted the technological significance of nano-scale phenomena and devices through speeches and the books Engines of Creation: The Coming Era of Nanotechnology (1986) and Nanosystems: Molecular Machinery, Manufacturing, and Computation, and so the term acquired its current sense. Engines of Creation: The Coming Era of Nanotechnology is considered the first book on the topic of nanotechnology.

Nanotechnology and nanoscience got started in the early 1980s with two major developments; the birth of cluster science and the invention of the scanning tunneling microscope (STM). This development led to the discovery of fullerenes in 1985 and carbon nanotubes a few years later.

In another development, the synthesis and properties of semiconductor nanocrystals was studied; this led to a fast increasing number of metal and metal oxide nanoparticles and quantum dots. The atomic force microscope (AFM or SFM) was invented six years after the STM was invented.

In 2000, the United States National Nanotechnology Initiative was founded to coordinate Federal nanotechnology research and development and is evaluated by the President's Council of Advisors on Science and Technology.

NANOMATERIALS

This includes subfields which develop or study materials having unique properties arising from their nanoscale dimensions.

Interface and colloid science has given rise to many materials which may be useful in nanotechnology, such as carbon nanotubes and other fullerenes, and various nanoparticles and nanorods. Nanomaterials with fast ion transport are related also to nanoionics and nanoelectronics.

Nanoscale materials can also be used for bulk applications; most present commercial applications of nanotechnology are of this flavor.

Progress has been made in using these materials for medical applications.

Nanoscale materials are sometimes used in solar cells which combats the cost of traditional Silicon solar cells

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Development of applications incorporating semiconductor nanoparticles to be used in the next generation of products, such as display technology, lighting, solar cells and biological imaging; see quantum dots.

NANOGENERATOR

“A device that uses nanowires for the generation of electricity is called a nanogenerator.”

The nanogenerator power is produced by the piezoelectric effect,

“A phenomenon in which certain materials – such as zinc oxide nanowires – produce electrical charges when they are bent and then relaxed.”

The wires are between 100 and 800 nanometers in diameter, and between 100 and 500 microns in length.

Fig: a nanogenerator shown with a pacemaker.

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NANOWIRES

A nanowire is a nanostructure, with the diameter of the order of a nanometer (10−9 meters).

Alternatively, nanowires can be defined as structures that have a thickness or diameter constrained to tens of nanometers or less and an unconstrained length. At these scales, quantum mechanical effects are important — which coined the term "quantum wires".

Many different types of nanowires exist, including metallic (e.g., Ni, Pt, Au), semiconducting (e.g., Si, InP, GaN, etc.), and insulating (e.g., SiO2, TiO2). Molecular nanowires are composed of repeating molecular units either organic (e.g. DNA) or inorganic (e.g. Mo6S9-xIx).

The nanowires could be used, in the near future, to link tiny components into extremely small circuits. Using nanotechnology, such components could be created out of chemical compounds. Examples of nanowires include inorganic molecular nanowires (Mo6S9-xIx, Li2Mo6Se6), which can have a diameter of 0.9 nm be hundreds of micrometers long. Other important examples are based on semiconductors such as InP, Si, GaN, etc., dielectrics (e.g. SiO2, TiO2), or metals (e.g. Ni, Pt).

There are many applications where nanowires may become important in electronic, opto-electronic and nanoelectromechanical devices, as additives in advanced composites, for metallic interconnects in nanoscale quantum devices, as field-emitters and as leads for biomolecular nanosensors.

Fig. Silica Nanowire

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Fabrication of Nanowires

Unlike natural resources such as wood, nanowires are not naturally found and must be synthesized. They can be fabricated from a wide variety of materials including germanium, metals, oxides, gallium nitrate, and silicon. Of course, there is no single standardized method for the fabrication of nanowires. However, the methods can be classified into either one of two categories.

The top down method include nanolithography via an election beam and a relatively recent expensive method known as Molecular Beam Epitaxy (MBE)

The bottom up method deals with direct chemical synthesis in a lab such as the Vapor-Liquid-Solid (VLS) synthesis method.

For laboratory production, nanowires are commonly either suspended (holding a wire at the extremities) or deposited (depositing a wire on a different surface.)

A suspended wire can be formed by bombarding a larger wire with highly energetic particles or etching it out of a larger wire. Another method used is to gently pierce a metal close to its melting point with the tip of a Scanning Tunneling Microscope and then pull up. An analogous example would be dipping a finger into a jar of honey and retracting it.

The nanowire is more than just a miniature wire; its uniqueness lies with specific properties that are useful for technological developments.

In large materials, particles are confined to certain energy regions because they do not have the necessary energy to escape the energy barrier. However, this is different for particles on the nanoscale because of the dual nature of the electron both as a particle and a wave.

In phenomena known as quantum tunneling, particles are found outside the confining potential in spite of their not having sufficient energy to cross the barrier. To better understand this, think of a ball bouncing against a wall. One would expect the ball to bounce off the wall and return in the direction it came from. This would be the case most of the times. However, although this seems impossible, there is almost a very small chance that the ball would penetrate the wall without breaking it. Moreover, this tunneling chance increases with a smaller ball. In fact, mathematicians have proved the tunneling probability decreases exponentially with the width of the barrier and the square root of the mass of the particle.

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Architecture of Nanogenerator

On the basis of architecture, Nanogenerators are made of two types:

- LING (lateral-nanowire-array integrated nanogenerator)

- VING (vertical nanowire array integrated nanogenerator)

Fabrication of LING

The detailed fabrication of the LING is accomplished following a five-step procedure (Fig. 4a).

The seed layer is first fabricated by partially covering patterned ZnO stripes with a chromium layer. To achieve this, a Kaptonw film with a thickness of 125 mm (Dupont) is cleaned using a standard procedure. A photoresist (Shipley Microposit 1813) is spun onto this film. The film is then patterned using a mask aligner, followed by consecutive deposition of 300-nm-thick ZnO and 5-nm-thick chromium layers. After developing and lifting off, a stripe-shaped ZnO pattern with a top layer of chromium is achieved (Fig. 4a(1)).

The second step is to deposit chromium only at one side of the ZnO stripe, leaving the other side exposed. The entire structure is spin-coated with a layer of photoresist, then a mask is used to cover one side while the other side is exposed for each ZnO strip by controlling its offset position. A layer of chromium (10 nm) is sputtered. A lift-off produced the structure shown in Fig. 4a(2).

The third step involved the growth of ZnO nanowire arrays (Fig. 4a(3)) using the wet chemical method at 80 8C for 12 h. Figure 4b shows a typical scanning electron microscopy (SEM) image of a horizontally grown ZnO nanowire array. The length of each nanowire is _5 mm and the diameter several hundred nanometres (Fig. 4e); the length and diameter of the nanowires could be easily controlled by refreshing the growth solution and increasing the growth time to ensure they are in contact with the other electrode.

In the fourth step, the gold electrode is deposited only on the side of the strip where the chromium layer is present (Fig. 4a(4)). The thickness of the gold layer is controlled to ensure a good connection between the nanowires and the electrodes (Fig. 4f ). Finally, the entire structure is packaged using insulating soft polymer, such as a photoresist (Fig. 4a(5)). This packaging layer fixed the ZnO nanowires firmly onto the substrate, allowing them to be synchronized throughout the mechanical stretching or releasing stages. Figure 4c,d shows optical microscopy images of the fabricated LING. The ZnO nanowire arrays are connected with each other, head-to-tail, by patterned electrodes. Figure 4e,f shows SEM images of the as-fabricated LING structure. A fully

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packaged, large-sized LING is presented in (Fig. 4g), and its flexibility is demonstrated in the inset.

Fabrication of VING

A piece of Si(100) wafer is cleaned by a standard cleaning process. A 20-nm layer of titanium and a 50-nm-thick layer of gold are consecutively deposited on top of the

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silicon wafer by magnetron plasma sputtering. The titanium thin film served as an adhesion layer to buffer the large lattice mismatch between the Si(100) surface with native oxide and Au(111) surface to improve interfacial bonding. The gold thin film is expected to act as an ‘intermediate layer’ to assist growth. The substrate is then annealed at 300 8C for 1 h to increase the crystallinity of the gold thin film. The nutrient solution is composed of a 1:1 ratio of zinc nitrate hexahydrate and hexamethylenetetramine (HMTA).

The substrate is placed face down at the top of the nutrient solution surface33. Owing to surface tension, the substrate could float at the top of the solution surface without sinking. The solution is then heated in a mechanical convection oven to 95 8C for 4 h.

Steps for fabrication of VING

On a gold-coated silicon wafer (a), ZnO nanowire arrays (b) are grown by low-temperature hydrothermal decomposition. PMMA, applied by spin coating (c), covers both the bottom and tips of the nanowire arrays. After oxygen plasma etching (d), the tips of the nanowires are exposed, fresh and clean, but the main body and bottoms of the nanowires are still fully enclosed, greatly improving the robustness of the structure. A platinum-coated flat electrode is placed on top of the nanowires (e) to form a firm

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Schottky contact. When a uniaxial stress is applied at the top electrode (f), the nanowires are readily compressed, the straining of the crystallographically aligned nanowires generating a macroscopic piezoelectric potential along the c-axis growing direction of the nanowires. g–i, SEM images of the as-grown ZnO nanowire arrays on the substrate (g), after spin-coating with PMMA (h) and after oxygen plasma etching (i).

DIFFERENT METHODS OF ENERGY GENERATION FROM NANOGENERATORS

VIBRATIONAL ENERGY

Could anyone think that hamsters help solve the world’s energy crisis? Probably not, but a hamster wearing a power-generating jacket is doing its own small part to provide a new and renewable source of electricity.

Image shows a hamster wearing a jacket on which nanogenerators are attached. The generators produce electricity due to piezoelectric effect as the animal runs and scratches.

MECHANICAL ENERGY

Scientists at the Georgia Institute of Technology, Professor Zong Lin Wang and

colleagues are working on harnessing the energy of the body's natural movements to

power small devices. Even the simple act of moving your fingers while typing creates

energy that could power a small device, and these researchers are showing that

nanotechnology can enable this transformation.

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HYDRAULIC ENERGY

Scientists at the Georgia Institute of Technology are in the process of developing a nanogenerator, a tiny device which produces energy from flowing blood, constricting blood vessels, or beating hearts. Researchers say that the devices could be used to power implantable biomedical electronics, or might be employed in biosensing, environmental monitoring, and personal electronics. The nanodevices generate power while warm-chillin' in bodily fluids or "other liquids," using ultrasonic waves as their energy source. Now if we can just combine this with the bloodstream bot, our self-powered swarm of robotic terror will be complete.

Bio-nano Generator

“A bio-nano generator is a nanoscale electrochemical device, like a fuel cell or galvanic cell, but drawing power from blood glucose in a living body, much the same as how the body generates energy from food.”

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To achieve the effect, an enzyme is used that is capable of stripping glucose of its electrons, freeing them for use in electrical devices.

A similar technology was presented in the Matrix series of science fiction major motion pictures, with robots shown enslaving mankind for its bio-energy. At the time, bio- nanogenerators were unheard of in popular culture, and the plot device of "a form of fusion" was used to make the harnessing of bio-electricity more plausible to the audience.

Scientists are working on a new type of nanogenerator that could draw the necessary energy from flowing blood in the human body, by using the beating heart and pulsating blood vessels. Once completed, this new cellular engine could find various applications, even beyond medicine.

Much of the research done on bio-nano generators is still experimental, with

Panasonic's Nanotechnology Research Laboratory among those at the forefront.

Zhong Lin Wang and colleagues at the Georgia Institute of Technology hope to be able to incorporate the new nanogenerator into biosensors, environmental monitoring devices and even personal electronics that will require no fuel source, internal or external.

It will produce its own electricity while immersed in biological fluids or other liquids, using ultrasonic waves as the energy source. So far, they achieved the nanogenerator effect in an array of nanowires that could produce as much as 4

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watts/cubic-centimeter.

How much Energy a person can generate?

The average person's body could, theoretically, generate 100 watts of electricity using a bio-nano generator. However, this estimate is only true if all food was converted to electricity, and the human body needs some energy consistently, so possible power generated is likely much lower. The electricity generated by such a device could power devices embedded in the body (such as pacemakers), or sugar-fed nanorobots.

Mechanical Energy our body produces:

Blood flow: 0.93 watts Exhaling: 1.00 watts Inhaling: 0.83 watts Walking: 67.0 watts

Electrical Energy available from our body:

Blood flow: 0.16 watts Exhaling: 0.17 watts Inhaling: 0.14 watts Walking: 11.4 watts

The above table shows a comparison of how much energy our body produces in different mechanical processes and how much amount is available to the devices paced in our body or outside the body.

Will nanogenerators replace batteries?

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Summary

Researchers at the Georgia Institute of Technology have built prototypes of a nanogenerator providing continuous electrical power by "harvesting mechanical energy from such environmental sources as ultrasonic waves, mechanical vibration or blood flow."

According to the scientists, the prototype could produce as much as 4 watts per cubic centimeter. This should be largely enough to power a broad range of nanoscale devices used for defense, environmental and biomedical applications, including biosensors implanted in the body or nanoscale robots. But will these nanogenerators be able to power bigger devices, such as our cell phones? The researchers think it's possible.

These nanogenerators are based on arrays of vertically-aligned zinc oxide nanowires and could one day power nanoscale devices without batteries or other external power sources. They have been developed by Zhong Lin Wang, professor in the School of Materials Science and Engineering at the Georgia Institute of Technology, and the members of his Nanoscience research group.

But will these nanogenerators be able to power bigger devices, such as our cell phones? "If you had a device like this in your shoes when you walked, you would be able to generate your own small current to power small electronics," Wang says. "Anything that makes the nanowires move within the generator can be used for generating power."

So let's wait.

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ACKNOWLEDGEMENTS

http://www.zdnet.com/blog/emergingtech/will-nanogenerators-replace-batteries/538

http://gtresearchnews.gatech.edu/images/hamster-power2.jpg

http://www.tgdaily.com/trendwatch-features/31506-nanogenerator-produces-electricity-from-ultrasonic-waves

http://www.zurich.ibm.com/pdf/heraeus/2007/abstracts/Wang.pdf

http://www.technologyreview.com/energy/22410/

http://www.technologyreview.com/energy/24428/

http://deviceace.com/science/372/nanogenerators-could-charge-your-electronic-devices-using-body-movements.html

http://www.technologyreview.com/energy/22103/

http://www.seminarprojects.com/Thread-nanotubes?pid=14706#pid14706

http://www.nanodic.com/nanobio/Bio-nano_generator.htm

http://www.smh.com.au/articles/2003/08/03/1059849278131.html

http://en.allexperts.com/e/b/bi/bio-nano_generator.htm

http://www.engadget.com/2007/07/23/nanogenerator-powers-up-inside-your-veins/

http://spie.org/documents/Newsroom/Imported/1040x/1040-2008-02-01.pdf

http://www.nanotechwire.com/news.asp?nid=4515

Magazine: Nature Nanotechnology, Article: Self-powered nanowire devicesSheng Xu†, Yong Qin†, Chen Xu†, Yaguang Wei, Rusen Yang and Zhong Lin Wang*

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