mems1

E

INTELLI-CAR (E)

KARTHIK.J.SHANKAR

N.D.VIGNESHWARIII YEAR, (ECE)

ADHIPARASAKTHI ENGINEERING COLLEGEMELMARUVATHURKANCHIPURAM (DT)

Contact:[email protected] [email protected]

MEMS

mailto:[email protected]

mailto:[email protected]

MEMS Intelli-car(e)

As a breakthrough technology,

allowing unparalleled synergy between

previously unrelated fields, many new

MEMS will emerge, expanding beyond that

which is currently identified or known. And

this is precisely the reason why this field has

become popular and powerful in such a

short span of time. This field is the study of

small mechanical devices and systems

MicroElectroMechanicalSystems is an

integration of micro electronics and macro

mechanics that holds the capacity to convert

physical stimuli, events, and parameters to

electrical, mechanical, and optical signals

and vice versa. MEMS are a logical

extension of microelectronics and IC

technology1-3, incorporating traditional

electronics with mechanical systems like

sensors and actuators.

Our design of the concept creation—

MEMS Intelli-car(e) is an integration of the

major advancements in the MEMS field viz.

Pico satellites and Automotive MEMS

along with a Revolutionary communication

and tracking system(GPS). Since all three

technologies have been proved effective in

their own right, an integration should be

considered feasible, possible and a

necessity. This concept is a dream effort to

provide something so complex and yet

simple.

This paper gives an overview of the

technologies used in brief and then proceeds

towards making an image out of the haze.

We then discuss about the feasibility of the

project. We look at a few among the

thousands of potential applications that it is

capable of. We also discuss how its future

looks.

Creative people from all technical

disciplines have important contributions to

make as the tech tool of MEMS is powerful

to make dreams come true.

“Think small,

Make it Large

I. Introduction

This field is the study of small mechanical

devices and systems. They range in size

from a few microns to a few millimeters.

The field is described by a wide variety of

other names: Micromechanics, Micro

System Technology, Micro Machines etc. It

encloses all aspects of science and

technology.

MEMS Intelli-car(e) 2

MicroElectroMechanicalSystems is an

integration of micro electronics and macro

mechanics that holds the capacity to convert

physical stimuli, events, and parameters to

electrical, mechanical, and optical signals

and vice versa. The root of MEMS can

potentially give rise to a tree of applications

that include intelligence control, decision-

making abilities, evolutionary learning,

unaided adaptation, self-organization, etc.

Apart from the field of diagnostics, signal

processing, and data acquisition features,

MEMS can also perform actuation and

sensing.

Things behave quite differently in the micro

domain. At these size scales, the standard

constructs of classical physics do not always

hold true. Due to MEMS' large surface area to

volume ratio, surface effects such as

electrostatics, friction and wetting dominate

volume effects such as inertia and thermal

mass. And forces like surface tension that

depend upon an edge become enormous.

An ant carrying many times its weight or a

water bug walking on the surface of a pond

are just two manifestations of this different

micro world

MEMS is an enabling technology allowing

the development of smart products,

augmenting the computational ability of

microelectronics with the perception and

control capabilities of micro sensors and

micro actuators and expanding the space of

possible designs and applications.

It promises to revolutionize nearly every

product category by bringing together

silicon-based microelectronics with

micromachining technology, making

possible the realization of complete systems-

on-a-chip. Creative people from all technical

disciplines have important contributions to

make.

Hope we will succeed in our little effort to

visualize a dream using this path-breaking

technology. This micro presentation will

help focus on a few macro applications from

a universe of opportunities!

II. Components

MEMS can include two or more of the

following subsystems: sensors, actuators, a

power supply, a central processing unit

(CPU) or microprocessor, and a

communication interface.


It consists of microstructures, micro sensors,

microelectronics, and micro- actuators.

Microstructure builds the framework of the

system.

Microsensor detects signals.

Microelectronics processes the signals and

gives commands to the Microactuator which

performs the task of reacting to these signals

in the designed manner.

III. Fabrication

Fabrication is the heart and soul of any

MEMS -based product. Micromechanical

parts tend to be rugged, respond rapidly, use

little power, occupy a small volume, and are

often much less expensive than conventional

macro parts. The following are the widely

preferred technique’s used:

i. LIGA:

(in German, Lithographie, Galvanoformung,

Abformung)The LIGA process exposes

PMMA (polymethyl methacrylate) plastic

with synchrotron radiation through a mask.

Exposed PMMA is then washed away,

leaving vertical wall structures with

spectacular accuracy. Metal is then plated

into the structure, replacing the PMMA that

was washed away. This metal piece

becomes the final part.

ii. Electro Discharge Machining

Matsushita has developed a new Electro

Discharge Machine with the capability to

make very small, precise parts out of almost

any material that conducts electricity. This

machine uses standard machine shop

tooling, and is compatible with machine

shop production techniques.

iii. Silicon Surface Micromachining:

Silicon surface micromachining uses the

same equipment and processes as the

electronics semiconductor industry. This has

led to a very rapid evolution of silicon

surface micromachining. This technique

deposits layers of sacrificial and structural

material on the surface of a silicon

wafer. Texas Instruments has built a large

array of mirrors by depositing and patterning

aluminum over a sacrificial polymer layer.

This system is being developed for

projection TV.


iv. Silicon Bulk Micromachining:

This process uses the whole bulk of the

semiconductor material. A large number of

structures can be made using the etch stop

planes in crystalline silicon. This mirror can

be integrated with other structures by wafer

bonding. Such structures are being used by

the automobile industry for air bag

deployment.

These techniques combined with wafer

bonding and boron diffusion allows complex

mechanical devices to be fabricated using

intra-model alignment process.

Alignment:

In order to make useful devices the patterns

for different lithography steps that belong to

a single structure must be aligned to one

another. The first pattern transferred to a

wafer usually includes a set of alignment

marks, which are high precision features that

are used as the reference when positioning

subsequent patterns.

Pico Satellites:

They are a major leap ahead as far as

MEMS enthusiasts are concerned. The

dimensions of a pico satellite are roughly

half the size of a multi-functionality

keyboard.

The first picosatellite fitted with MEMS for

all major functions was launched by the

Aerospace Corporation. It measured

2.5x7.5x10 cm. The satellite weighed just a

little over 250 Gms. This satellite was

launched on the 26th of January 2000. This

was the first time a device used MEMS RF

switches for long distance communication.

Communication to the remote object was

established in a fortnight. The satellite

stayed in orbit for a couple of months before

it was brought back. During the stay, the

satellite monitored atmospheric conditions

and was in constant contact with the ground

control room.

Just as the world seems to have been

shrunk in size due to the telephone, internet

and other communication modes, the larger

picture is to shrink the universe. Constant

communication to a distant object that is

able to fulfill all its requirements on its own


without any help is the next best thing in

space research technology. The small size of

a pico satellite makes it use specific

eliminating unwanted expenditure to obtain

useless data. Surveillance cost can be

drastically reduced using this technology.

The use of easy-to manufacture MEMS

chips combine to form a robust working

mechanism.

The cost efficiency of MEMS

induces into the picosatellite its properties of

size and space conservation along with the

required degree of precision and ruggedness

for its active working in the long term.

The pico satellite we propose to be

used will be the size of a computer monitor

which will have a TFSA(Thin Film Solar

array). This film can provide the energy

requirements for a long duration of time

making it potentially maintenance-free.

Picosat showing an attached foldable Thin film Solar Array

The Global Positioning System (GPS) is a

satellite-based navigation system made up of

a network of 24 satellites placed into orbit

by the U.S. Department of Defense. GPS

was originally intended for military

applications, but in the 1980s, the

government made the system available for

civilian use. GPS works in any weather

conditions, anywhere in the world, 24 hours

a day.

Working:

GPS satellites circle the earth twice a

day in a very precise orbit and transmit

signal information to earth. GPS receivers

take this information and use triangulation to

calculate the user's exact location.

Essentially, the GPS receiver compares the

time a signal was transmitted by a satellite

with the time it was received. The time

difference tells the GPS receiver how far

away the satellite is. Now, with distance

measurements from a few more satellites,

the receiver can determine the user's

position and display it on the unit's

electronic map.

Here are some other interesting facts about

the GPS satellites :A GPS satellite weighs

approximately 2,000 pounds and is about 17

feet across with the solar panels extended.


Transmitter power is only 50

watts .Signal:GPS satellites transmit two

low power radio signals in the UHF band.

The signals travel by line of sight, meaning

they will pass through clouds, glass and

plastic but will not go through most solid

objects such as buildings and mountains.

A GPS signal contains three different

bits of information — a pseudorandom code,

ephemeris data and almanac data. The

pseudorandom code is simply an I.D. code

that identifies which satellite is transmitting

information. Ephemeris data tells the GPS

receiver where each GPS satellite should be

at any time throughout the day. Each

satellite transmits ephemeris data showing

the orbital information for that satellite and

for every other satellite in the system.

Almanac data, which is constantly

transmitted by each satellite, contains

important information about the status of the

satellite (healthy or unhealthy), current date

and time. This part of the signal is essential

for determining a position.

MEMS Sensors:

The sensors designed using MEMS are well

suited for high volume applications that

demand high-performance sensors at low

costs. They also provide a high degree of

reliability and consistency. Each sensor

contains thousands of tiny drums on the

surface of a silicon chip where each is only

as large as the width of a human hair. The

drum structure consists of a thin nitride

membrane and aluminium electrode

suspended over a cavity.

MEMS accelerometers are quickly

replacing conventional accelerometers for

crash air-bag deployment systems in

automobiles. The conventional approach

uses several bulky accelerometers made of

discrete components mounted in the front of

the car with separate electronics near the air-

bag; this approach costs over $50 per

automobile. MEMS have made it possible to


integrate the accelerometer and electronics

onto a single silicon chip at a cost between

$5 to $10. These MEMS accelerometers are

much smaller, more functional, lighter, more

reliable, and are produced for a fraction of

the cost of the conventional macroscale

accelerometer elements.

MEMS devices are extremely small -- for

example, MEMS has made possible

electrically-driven motors smaller than the

diameter of a human hair (right) -- but

MEMS is not primarily about size.

MEMS is also not about making things out

of silicon, even though silicon possesses

excellent materials properties,

which make it an attractive choice for many

high-performance mechanical applications;

for example, the strength-to-weight ratio for

silicon is higher than many other

engineering materials which allows very

high-bandwidth mechanical devices to be

realized. Instead, the deep insight of MEMS

is as a new manufacturing technology, a way

of making complex electromechanical

systems using batch fabrication techniques

similar to those used for integrated circuits,

and uniting these electromechanical

elements together with electronics.


Figure showing an automobile designed by

Mario H Castro Cedano (Rochester Institute

of technology) using MEMS sensors.

The car is fit with 12 independent sensor

units made using MEMS. Each sensor acts

as if it has a mind of its own by responding

selectively to changes in pressure, flow-

direction and temperature.

Each sensor is unique and has the ability to

perform accurately only that for which it is

designed. Thus no 2 sensors on the car are

same although they detect the same

quantities.

Now we shall shift our focus onto the GPS

sensor and inertial navigator present next to

the steering wheel. The sensor is made of

RF switches that are used for high frequency

communication businesses and other

multimedia consumers at a reasonable cost.

Automotive intelligence (AI):

The term is used by us to describe a

pioneering idea that can take the Automobile

industry by storm. Driving a car will never

be the same with our proposed plan of

creating an internet-like revolution in this

field.

We have so far discussed about 3

non-related or weakly linked technologies

each of which has been tried and tested and

have managed to live up to the expectations.

What if: 1. your car can tell you your exact

position on the surface of the earth? 2. Your

car can tell you where the roads are blocked

or about traffic congestion to help you avoid

those routes? 3. Your car can give speeds of

all other vehicles on the road to help you

keep from bumping into the slow ones? 4.

Your car can track those who are near and

dear to you? 5. Your car can find the way

out of nowhere when you’re lost? 6. Your

car can tell you how much distance you can

travel without having to re-fill? 7. Your car

can find the nearest filling station for you?

8. Your car can tell you about the weather in

your locality?

All this and more is possible by our

proposed plan of integrating Pico-satellites,

GPS and the MEMS car. The car has a GPS

sensor that has RF switches to communicate

with the satellites. These satellites are

planned to be the picosatellites that are

constructed using MEMS. These satellites

also have RF switches in them to establish

connection on a specific frequency band.

The picosatellites can be designed to

perform the various functions of a GPS

satellite. These Satellites cost roughly one-

tenth of that of a normal GPS satellite.


Applications:

1. The police are on the look-out for a

vicious criminal on the run in a fast paced

car. The police car is equipped with our

proposed lay-out of full fledged technology.

The criminal can be tracked without his

knowledge on the touch of a button. The

processes that follow are the routine police

formalities that include chase, interrupt and

capture.

2. A severe case of rash driving leaves 2

people badly hurt. The police retrieve the

satellite data from the cache as to find whose

car was on the road at the time of the

accident. With the proven accuracy of the

satellite tracking system, it can be used as

evidence against the offender and help the

victim get speedy justice.

3. A VVIP car needs to have as many as 12

cars to ensure fool-proof security to the

person. With an intelligent automobile that

can find suspicious movements in a radius

of 1.5 km around the car, the security might

be reduced to just 2 cars to prevent any

mishap.

4. Remember that in Mumbai (26 June

2005) 5 cars were completely immersed in

water and all occupants (16 in all) had been

suffocated to death. Add the incident in

Chennai of CO poisoning and we are forced

to think whether there is a way out of this at

all? Yes, we have a solution. An intelligent

car tells you that the weather might become

worse in a short time, so you can plan your

safety and using the same system, locate an

inn or a motel to spend the time safely. 2

days later, after the water has receded,

switch on the s-o-c and locate the nearest car

repair centre to straighten the problems due

to the water.

As for the incident in Chennai, it

does not need a GPS satellite to prevent a

mishap. The car has an exhaust gas sensor

that displays a critical error message as soon

as reverse gas-flow is detected.

These are micro examples of this

project with macro-potentials. Even if used

to half of its potential, this may create a

revolution in automotive industry and put

the roads in order.

There is immense scope for further

expansion of such applications to make

work easy for the cops and provide state-of-

the-art technology to the common man at

affordable prices.


WORKING MODEL OF MEMS

INTELLIGENTCAR:

Future Trends:

The present day technology and all

aspects concerned with MEMS are tailor

made for application in cars. The main

challenge lies in expanding this innovative

technology to other automobiles as well.

More innovation is still possible in cars. The

development

Of a technology that requires the car-users


to prove their identity before logging into

their respective cars is an example .This

approach may further result in a reduction in

the car thefts happening in and around the

world. A web-cam like device can be

developed which can be used by car-drivers

to communicate with their loved ones. Car

accidents due to brake failure can also be

prevented.

“Every Theory is always perfect until it has

been verified practically”.

This ambitious project needs years of

research and tonnes of investment. This is

the only barrier between us and the next

level of transport.

Conclusion:

This is only a very brief overview of the

MEMS field. MEMS is still the subject of

broad and diverse research efforts. A

significant growth area for MEMS today is

in telecommunications where the technology

is being used for wireless applications as

well as in optical networks.

As a breakthrough technology, allowing

unparalleled synergy between previously

unrelated fields, many new MEMS

applications will emerge, expanding beyond

that which is currently identified or known.

And this is precisely the reason why this

field has become popular and powerful in

such a short span of time. The victory of

MEMS lies in the fact that it has been able

to hold to it’ s ground, when even smaller

technologies such as nanotechnology are

ruling the roost. And that is why MEMS is

an everlasting indispensable field. MEMS

devices are extremely small -- for example,

MEMS has made possible electrically-

driven motors smaller than the diameter of a

human hair -- but MEMS is not primarily

about size.

MEMS is also not about making things out

of silicon, even though silicon possesses

excellent materials properties, which make it

an attractive choice for many high-

performance mechanical applications.

Instead, the deep insight of MEMS is as a

new manufacturing technology, a way of

making complex electromechanical systems

using batch fabrication techniques similar to

those used for integrated circuits, and

uniting these electromechanical elements

together with electronics.

Bibliography

1. W.S.N. Trimmer, “Microbots and

Micromechanical Systems,” Sensors and

Actuators, September 1989.


2. G. Stix, “Little Big Science,” Scientific

American, September 2001.

3. M.J. Madou, Fundamentals of Micro

fabrication, CRC Press LLC, Boca Raton,

Florida,

4. Lyshevski, Sergey Edward. MEMS and

NEMS Systems, Devices, and Structures.

CRC

5. Ramakrishnan, Srinivas, Collis, S. Scott.

“Turbulence Control Simulation”.

6. “MicroElectroMechanical Systems”.

National Institute of Standards and

Technology.

7. “What is MEMS Technology?” MEMS

clearing house.

8. MARIO H. CASTRO-CEDENO‘s project

on Automotive MEMS

Mario H. Castro-Cedano is Assistant

Professor in the Department of

Mechanical and Manufacturing

Engineering Technology and Packaging

Science at the Rochester Institute of

Technology (RIT) in Rochester, NY.


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