NANO TECHNOLOGY COOLING BY GIRIJA

1. ABSTRACT
Nanotechnology 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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2. INTRODUCTION
The 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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3. CAUSES OF HEAT GENERATION
The 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
Passive heat sink on a chip
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. Active heat sink with a
Fan and heat pipes
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4. 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 in DIY Water cooling setup
heat sinks, making it suitable for overclocking and high showing 12v pump, CPU
performance computer applications. Water block
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 A graphics card with a heat
larger radiator heat sink. Both heat sinks are hollow as is pipe cooler design
the 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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5. NANOTECHNOLOGY
The 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 Atom
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.
Molecules
NANO-LIGHTING
A 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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6. 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 COOLING
The cooling of computer chips is incorporated through two regions respectively,
 Ion – Generating region
 Ion – pumping region
ION – GENERATING REGION Shows the electron emission process
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 Pumping Region Process
region of electrodes and pumped forward by changing the voltages in those electrodes. This
region consists of a series of
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7. 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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8. 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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9.  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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10. CARBON NANORIBBONS FOR
SMALLER, SPEEDIER COMPUTER
CHIPS
Stanford 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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11. 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 contact Basic Structure of NanoWire
from 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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12. FUTURE DEVELOPMENTS
Silicon 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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13. CONCLUSION
Cooling 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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14. REFERENCE
I. 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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15. REFERENCE
I. 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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