ABSTRACTNanotechnology is one of the fast developing branches of hybrid science combining

physics, chemistry and engineering. One of the major implications of this technology will

have on the future field of engineering. Future computer chips will contain more circuitry and

components, causing them to generate additional heat and requiring innovative cooling

methods.

This paper explains the role of nanotechnology in increasing the efficiency of the

computer. The most innovative and emerging technique, using a liquid to cool electronic

circuits, however, poses many challenges, as they are expensive and prone to breakdown. So,

our aim here is to create a type of system for the chips to cool such that the challenges

hindered are overcome. Thus industry has developed a new cooling method that uses air. The

key attribute of this work is that it sticks with air cooling while possibly providing the same

rate of cooling as a liquid. We explain the cooling of future computers using nanotechnology.

This method uses new type of cooling technology for computers that uses a sort of nano-

lightning to create tiny wind of currents that would self-cool the chips without any

requirement of an external mean. It explains about the carbon nanoribbons for smaller,

speedier computer chips and also the computer memory designed in nanoscale.

INDEX TERM

OVERCLOCKING: Extra cooling which is usually required by those who run parts of their

computer (such as the CPU and GPU) at higher voltages and frequencies than manufacturer

specifications call for.

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INTRODUCTIONThe present trends used for reducing the heat in the computer are Liquid submersion

cooling, Passive heat-sink cooling, Active heat-sink cooling, Peltier cooling or thermoelectric

cooling, Water cooling Heat pipe ,Phase-change cooling, Integrated chip cooling techniques.

However these techniques possess certain drawbacks which can be overcome by the new

technique. The new technique works by generating ions or electrically charged atoms using

electrodes placed close to one another on a computer chip. Generated ions are passed from

electrode to electrode, with collisions between ions and neutral air atoms propelling the air

forward in what is called the corona wind effect – the process that cools. The nanoscale

computer memory can retrieve data 1000 times faster than the normal wire. The entire thing

would sit on, and be integrated into, a chip that is 10mmx10mm.

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CAUSES OF HEAT GENERATIONThe amount of heat generated by an integrated circuit (e.g., a CPU), the prime cause of

heat build up in modern computers, is a function of the efficiency of its design, the technology used in its construction and the frequency and voltage at which it operates. In operation, the temperature of a computer's components will rise until the heat lost to the surroundings is equal to the heat produced by the component, and thus the temperature of the component reaches equilibrium. For reliable operation, the equilibrium temperature must be sufficiently low for the structure of the computer's circuits to survive. Some of popular cooling techniques are discussed below:

1) PASSIVE HEAT-SINK COOLING:

Passive heat-sink cooling involves attaching a block of machined or extruded metal to the part that needs cooling. A thermal adhesive may be used. More commonly for a personal-computer CPU, a clamp holds the heat sink directly over the chip, with a thermal grease or thermal pad spread between. This block usually has fins and ridges to increase its surface area. The heat conductivity of metal is much better than that of air, and it radiates heat better than does the component that it is protecting (usually an integrated circuit or CPU). Until recently, fan-cooled aluminium heat sinks were the norm for desktop computers. Today, many heat sinks feature copper base-plates or are entirely made of copper, and mount fans of considerable size and power.

Dust buildup between the metal fins of a heat sink gradually reduces efficiency, but can be countered with a gas duster by blowing away the dust along with any other unwanted excess material. Passive heat sinks are commonly found on older CPUs, parts that do not get very hot (such as the chipset), and low-power computers. Usually a heat-sink is attached to the integrated heat spreader (IHS), essentially a large, flat plate attached to the CPU, with conduction paste layered between. This dissipates or spreads the heat locally. Unlike a heat sink, a spreader is meant to redistribute heat, not to remove it. In addition, the IHS protects the fragile CPU. Passive cooling involves no fan noise.

2) ACTIVE HEAT-SINK COOLING:

Active heat-sink cooling uses the same principle as passive, with the addition of a fan that blows over or through the heat sink. The air movement increases the rate at which the heat sink can exchange heat with the ambient air. Active heat sinks are the primary method of cooling modern processors and graphics cards.

The buildup of dust is greatly increased with active heat-sink cooling, because the fan continually takes in the dust present in the surrounding air.

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Passive heat sink on a chip

Active heat sink with aFan and heat pipes

3) WATER COOLING:

While originally limited to mainframe computers, water cooling has become a practice largely associated with overclocking in the form of either manufactured kits, or in the form of do-it-yourself setups assembled from individually gathered parts. The past few years has seen water cooling increasing its popularity with pre-assembled, moderate to high performance, desktop computers. Water has the ability to dissipate more heat from the parts being cooled than the various types of metals used inheat sinks, making it suitable for overclocking and high performance computer applications.

Advantages to water cooling include the fact that a system is not limited to cooling one component, but can be set up to cool the central processing unit, graphics processing unit, and/or other components at the same time with the same system. As opposed to air cooling, water cooling is also influenced less by the ambient temperature. Water cooling's comparatively low noise-level compares favorably to that of active cooling, which can become quite noisy. One disadvantage to water cooling is the potential for a coolant leak. Leaked coolant can damage any electronic components it comes in contact with. Another drawback to water cooling is the complexity of the system.

4) HEAT PIPE:

A heat pipe is a hollow tube containing a heat transfer liquid. As the liquid evaporates, it carries heat to the cool end, where it condenses and then returns to the hot end. Heat pipes thus have a much higher effective thermal conductivity. For use in computers, the heat sink on the CPU is attached to a larger radiator heat sink. Both heat sinks are hollow as isthe attachment between them, creating one large heat pipe that transfers heat from the CPU to the radiator, which is then cooled using some conventional method. This method is expensive and usually used when space is tight or absolute quiet is needed. Because of the efficiency of this method of cooling, many desktop CPUs and GPUs, as well as high end chipsets, use heat pipes in addition to active fan-based cooling to remain within safe operating temperatures.

5) USE OF ROUNDED CABLES:

Older PCs use flat ribbon cables to connect storage drives. These large flat cables greatly impede airflow by causing drag and turbulence. Over lockers and modders often replace these with rounded cables, with the conductive wires bunched together tightly to reduce surface area. Theoretically, the parallel strands of conductors in a ribbon cable serve to reduce crosstalk, but there is no empirical evidence of rounding cables reducing performance. This may be because the length of the cable is short enough so that the effect of crosstalk is negligible. Problems usually arise when the cable is not electromagnetically protected and the length is considerable, a more frequent occurrence with older network cables. In order to have a still better efficiency, cables are replaced by Nanotechnology.

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DIY Water cooling setup showing 12v pump, CPU

Water block

A graphics card with a heat pipe cooler design

NANOTECHNOLOGYThe word nanotechnology is derived from the Greek word

‘nanos’ meaning ‘dwarf’. Nanotechnology involves working with matter at the scale of one-billionth of a meter (1mm). It refers to the manipulation of matter on the minutest scale i.e. atoms and molecules. Figure shows the process of Atom.

Every element is composed of matter. Matter is again the

composition of infinite atoms. The atoms cluster together to form molecules, which, in turn, combine with several other molecules to form a basic molecular structure. The molecular structures have specific density, shape, hardness and other physical properties of that particular element. These very properties are taken to consideration when we talk of nanotechnology. The properties of matter depend on how atoms are arranged in the matter. It is possible to rearrange atoms in the matter. If we rearrange atoms in coal we get diamonds. When we rearrange atoms of sand with addition of little impurities we get computer chips. Thus nanotechnology is about rearranging of atoms and placing each atom in the right place. Nanotechnology crosses and unites academic fields of physics, chemistry, biology and even computer science taking shape to create ‘smart materials’ roughly the size of atoms, possessing far better characteristics than what they originally had.

A major challenge for nanotechnology is to get control on the characteristics of the matter to develop highly efficient systems. The goal of nanotechnology is to manipulate atoms individually and place them in a pattern to produce a desired structure. The figure shows Molecules process.

NANO-LIGHTINGA new type of cooling technology for computers that uses a sort of nano-lightning to

create tiny wind currents is used to cool the chips. Future computer chips will generate additional heat, requiring innovative cooling methods, as they will contain more circuitry and components. Engineers are studying ways to improve cooling technologies, including systems that circulate liquids to draw heat from chips. Using a liquid to cool electronic circuits, however, poses many challenges, and industry would rather develop new cooling methods that use air.

Future cooling devices based on the design will have an ion-generation region, where electrons are released, and a pumping region, made up of another set of electrodes needed to create the cooling effect. The key attribute of this work is that it sticks with air cooling while possibly providing the same rate of cooling as a liquid. Chips in desktop computers currently are cooled with ‘heat sinks’ that contain fins to dissipate heat. The heat sinks are connected to bulky fan assemblies to carry away the heated air.

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Atom

Molecules

We need an external means of creating air. We need the fan. Here, the creation of air as well as the cooling is all happening on one chip. That’s the key value of this idea. The researchers envision cooling devices that are small enough to fit on individual chips, actually making up a layer of the chip. The entire thing would sit on, and be integrated into, a chip that is 10mmx10mm.

REGIONS OF COOLINGThe cooling of computer chips is incorporated through two regions respectively,

Ion – Generating region

Ion – pumping region

ION – GENERATING REGION

This region consists of electrodes for electron emission and ion creation. Using electrodes placed close to one another on a computer chip, the new technique works by generating ions – or electrically charged atoms. Negatively charged electrodes, or cathodes, are made of nanotubes of carbon with tips only as wide as five nanometers, or billionths of a meter. Carbon nanotubes are tiny cylindrical structures that are some 50,000 times thinner than the diameter of human hair.

A carbon nanotubes is a sheet of carbon atoms joined in a pattern of hexagons and rolled into a cylinder, like chicken wire. Where the two ends wrap around and meet determines the conductive properties of the nanotube. Line the ends up one way, and the nanotube conducts electricity like a metal. But line them up another way, and the nanotube heaves like a semiconductor. Roll one nanotube around another, and you get a multi-walled nanotube – a metal – type inside a semiconductor inside a metal – type, for example. The negatively charged nanotubes discharge electrons toward the positively charged electrodes when voltage is passed into the electrodes.

These carbon nanotubes combine to form electrodes to generate ions that cause the ionization of air, which in turn creates tiny wind currents thereby cooling the chips.The researchers are able to create the ionizing effect with low voltage because the tips of the nanotubes are extremely narrow and the oppositely charged electrodes are spaced apart only about 10 microns, or one – tenth the width of a human hair.

ION – PUMPING REGION

Pumping region made up of another set of electrodes needed to

create the cooling effect. Clouds of ions are created when

electrons react with air can then be attracted by the second

region of electrodes and pumped forward by changing the voltages in those electrodes. This

region consists of a series of

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Shows the electron emission process

Pumping Region Process

electrodes, with descending positive polarity with the final one negatively charged. Usually the series consist of three electrodes with the first one highly positive, the next one less positive and the last one negative. This combination creates a kind of environment so that the ions are pumped out resulting in an ionic breeze which cools the computer chips. The creation of ionic breeze is explained by “Corona Wind Effect”.

Corona Wind Effect: A corona wind is created by the ions that follow an electrical field set up by opposite charges. In man – made devices, generated ions are passed from electrode to electrode, in the mode of a charge – coupled device, with collisions between ions and neutral air atoms propelling the air forward in what is called the corona wind effect (Ionic Breeze). The corona wind effect was explained by Biefeld and Brown. This effect is also known as Biefeld-Brown Effect.

Biefeld – Brown Effect: The Biefeld – Brown effect is an electro kinetic effect that was discovered by Thomas Townsend Brown and Dr. Paul Alfred Biefeld. The effect is more widely referred to as Electro – hydrodynamics (EHD) or sometimes electro – fluid – dynamics.

EFFECT ANALYSIS:

The effect relies on corona discharge, which allows atoms to become ionized near sharp points and edges – this belief is perpetuated in the construction of pointy lightning rods historically (though rounded or spherical topped rods are better than the pointed rods).

Usually, two electrodes are used with a high voltage between them, about 20kV, where one electrode is small or sharp, and the other larger and smoother. This creates a high field gradient around the smaller, positively charged electrode. Around this electrode, electrons are stripped of the atoms in the surrounding medium they are literally pulled right off by the electrode’s charge. The electrons quickly move to the electrode, and are driven to the negative electrode by the voltage. This leaves a cloud of positively charged ions in the medium, which are attracted to the negative electrode. This also drags along some of the surrounding medium, causing what is known as ion wind, which creates a breeze of considerably greater magnitude than the ions themselves account for.

Unipolar charge current can be generated through corona discharge from a thin wire enclosed in a shield electrode. Except for an ionization sheath adjacent to the coronating wire surface, most parts of the region in the enclosing shield contain drifting ions of a single polarity in response to the electric field. Momentum transfer as a consequence of collisions between drifting ions and electrically neutral air molecules gives rise to the electro hydrodynamic flow known as corona wind.

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COOLING METHODOLOGY USING NANOTUBES

The steps involved in the cooling process are as follows:

Carbon nanotube electrodes placed close to one another on a computer chip and voltage is passed into the electrodes.

When voltage is passed into the electrodes the negatively charged nanotubes discharge electrons towards the positively charged electrodes.

The electrons react with surrounding air, causing the air molecules to be ionized just as electrons in the atmosphere ionize air in clouds.

This ionization of air leads to an imbalance of charges that eventually result in lightning bolts.

To create lightning we need tens of kilovolts, but we do it with 100 volts or less, in simple term, we are generating lighting on a nano-scale here.

The researchers are able to create the ionizing effect with low voltage because the tips of the nanotubes are extremely narrow and the oppositely charged electrodes are spaced apart only about 10 microns, or one – tenth the width of human hair.

The ionized air molecules cause currents like those created by the “corona wind” phenomenon, which happens between electrodes at voltages higher than 10 kilovolts, or 10,000 volts.

Clouds of ions created when electrons react with air can then be attracted by the second region of electrodes and pumped forward by changing the voltages in those electrodes.

The voltages are rapidly switched from one electrode to the next in such a way that the clouds of ions move forward.

As the ions move forward, they make repeated collisions with neutral molecules, producing the breeze.

Voltages are switched at the right frequency so that the ion cloud is constantly moving forward causing the breeze to flow.

The pumping concept works with a region of electrodes made of many series, each series containing three electrodes.

The first in the series is the most positively charged, followed by an electrode that has a less – positive charge and then a third electrode that is negative.

Switching the voltages from one electrode to the next causes the charges to move forward, which in turn moves the ion clouds.

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Generated ions are passed from electrode to electrode, in the mode of a charge – coupled device, with collisions between ions and neutral air atoms propelling the air forward in what is called the corona wind effect

The researchers nano sized the corona wind effect and combined it with micro fluidic channels with embedded, megahertz – sequenced electrodes to create suitable for pumping heat – laden air molecules literally through the core of a chip and out the other side.

Thus the process of cooling is carried out so that the heat is given out without providing any external means.

ADVANTAGES OF SELF COOLING:

Additional cost for providing external cooling (coolers, air – conditioner etc) can be eliminated.

Size of computers will be smaller in near future compared to those used at present.

No moving parts inside the computer, hence there will be more reliable and noiseless.

Self – cooling of chips will increase the life expectancy of the chips and hence increase the life of appliance.

Additional and more advanced circuitry can be designed and fabricated within a single chip.

In conventional cooling we need an external means of creating air. We need the fan. Here, the creation of air as well as the cooling is all happening on one chip. That’s the key value of this idea.

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CARBON NANORIBBONS FOR SMALLER, SPEEDIER COMPUTER

CHIPSStanford chemists have developed a new way to make transistors out of carbon

nanoribbons. The devices could someday be integrated into high-performance computer chips to increase their speed and generate less heat, which can damage today's silicon-based chips when transistors are packed together tightly. Researchers have made nanoribbons, strips of carbon 50,000-times thinner than a human hair, that are smoother and narrower than nanoribbons made through other techniques.

A schematic of graphene nanoribbon field-effect transistor with palladium contacts (S,D) on a 10 nm thick insulating silicon dioxide surface (purple). Beneath the Si02 layer is a highly conductive silicon layer (G)

The researchers have made the transistors called "field-effect transistors"—a critical component of computer chips—with graphene that can operate at room temperature. Graphene is a form of carbon derived from graphite. Other graphene transistors, made with wider nanoribbons or thin films, require much lower temperatures. Field-effect transistors are the key elements of computer chips, acting as data carriers from one place to another. They are composed of a semiconductor channel sandwiched between two metal electrodes. In the presence of an electric field, a charged metal plate can draw positive and negative charges in and out of the semiconductor. This allows the electric current to either pass through or be blocked, which in turn controls how the devices can be switched on and off, thereby regulating the flow of data.

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COMPUTER MEMORY DESIGNED IN NANOSCALE

The technology have developed nanowires capable of storing computer data for 100,000 years and retrieving that data a thousand times faster than existing portable memory devices such as Flash memory and micro-drives, all using less power and space than current memory technologies. These nano-wires can retrieve data 1000 times faster than the normal wire. This new form of memory has the potential to revolutionize the way we share information, transfer data and even download entertainment as consumers. The researchers grew the nanowires onto a layered oxide-nitride-oxide substrate. Applying a positive voltage across the wires causes electrons in the wires to tunnel down into the substrate, charging it. A negative voltage causes the electrons to tunnel back up into the wires. This process is the key to the device's memory function: when fully charged, each nanowire device stores a single bit of information, either a "0" or a "1" depending on the position of the electrons. When no voltage is present, the stored information can be read.

The device combines the excellent electronic properties of nanowires with established technology, and thus has several characteristics that make it very promising for applications in non-volatile memory. For example, it has simple read, write, and erase capabilities. It boasts a large memory window--the voltage range over which it stores information--which indicates good memory retention and a high resistance to disturbances from outside voltages. The device also has a large on/off current ratio, a property that allows the circuit to clearly distinguish between the "0" and "1" states.

The basic structure of the nanowire devices is based on a sandwich geometry in which a nanowire (n-type zinc oxide) is placed between the substrate (heavily doped p-type silicon) and a top metallic contact, using spin-on glass as an insulating spacer layer to prevent the metal contactfrom shorting to the substrate (as shown in (a) and (b)). This allows for uniform injection of current along the length of the nanowire. A finished wafer using the team’s method is shown in (c), with a typical device shown in (d). Note that a stray nanowire intercepts the device on the upper part of (d). The oval feature surrounding the stray nanowire is due to the varying thickness of the spin-on glass film. When a voltage is applied to this device, it emits ultraviolet light (as shown in image (e) obtained with a CCD camera) with a peak wavelength of ~380 nm.

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Basic Structure of NanoWire

FUTURE DEVELOPMENTSSilicon Nanowires Upgrade Data-Storage Technology – It is a fabricated memory

device that combines silicon nanowires with a more traditional type of data-storage. Their hybrid structure may be more reliable than other nanowire-based memory devices recently built and more easily integrated into commercial applications.

Another version of the design might replace the carbon nanotubes with a thin film of diamond, which would be sturdier and easier to fabricate than the nanotubes. The grain boundaries in the diamond film provide the same kind of opportunity for electron emission and ion generation as a carbon nanotube.

Most features of the device could be manufactured with conventional silicon fabrication techniques used in the semiconductor industry to make computer chips. Electronics manufactures ultimately are most interested in reliability because so much of what we do now depends completely on the reliability of our systems. This cooling method would have no moving parts making it quiet and reliable.

Integrated Nanowire Sensor Circuitry -Integrated sensor circuit based on nanowire arrays, combining light sensors and electronics made of different crystalline materials.

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CONCLUSIONCooling of computer chips is indeed a matter of highest concern in today’s electronic

world. With greater development in the field of IC fabrication, more complex circuitry may be designed. Additional heat production eventually leads us for requirement of innovative cooling methods. Chips in desktop computers currently are cooled with ‘heat sinks’ that contain fins to dissipate heat. The heat sinks are connected to bulky fan assemblies to carry away the heated air. External means of creating air and the fan are needed. Conventional fans use too much space and energy for laptop computers, which have to be cooled entirely with heat sinks and tube – like “heat pipes” that dissipate heat. Liquid cooling, on the other hand, would be expensive and prone to break down. For that reason, the ion – driven cooling device represents a way to increase cooling capacity in laptops, meaning they could use higher performance chips that generate too much heat for current laptops. Moreover the entire thing could sit on, and be integrated into, a chip that is 10 x 10mm.The researchers envision cooling devices that are small enough to fit on individual chips, actually making up a layer of the chip.

Here, the creation of air as well as the cooling is all happening on one chip. Hence self – cooling of computer chips is far more beneficial than the conventional one and moreover it paves way for innovative thinking and research.

Nanotechnology is used in computers for improving its efficiency. The nanowires, nano cooling techniques provides with high reliability, increased performance efficiency.

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REFERENCEI. en.wikipedia.org/wiki/Nanotechnology/

II. www.nanowerk.com/nanotechnology/

III. www.xbitlabs.com

IV. www.nanotech.now.com

V. www.crnano.org

VI. www.dailytech.com/Nanotechnology...Cooling/

VII. www.azonano.com

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