mems and application

8/4/2019 Mems and Application

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KONGU ENGINEERINGKONGU ENGINEERING

COLLEGECOLLEGE

PERUNDURAI, ERODE.PERUNDURAI, ERODE.

Renaissance07

PAPER ON MEMS AND ITS APPLICATIONS

Presented by

K.Devi ([email protected])

D.Kokila ([email protected])

III-CSE-A
mailto:[email protected]:[email protected]:[email protected]:[email protected]


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ABSTRACT:

This paper is about MEMS, which is the recent technology introduced in every field.

The main objective of this paper is to know about MEMS and its applications. Its

biomedical application holds well in recent days. The paper explains some of the

applications of MEMS. It mainly illustrates the switching architecture in optical

communication, since the MEMS mirror switches are reliable than the digital electronic

switches; it has been illustrated about the three types of micro mirrors. The MEMS-

Based, Optical Identification and Communication System with bi-directional half-duplex

communication from an interrogating transceiver hold well in hazardous environment.

INTRODUCTION:INTRODUCTION:

A machine that is so small that it is invisible to the naked eye. The devices that is the

size of grains with mechanical parts smaller than a dust mite (Fig. 1), and entering a

realm where the dominating physical principles is no longer gravity and inertia, but are

substituted by atomic forces and surface science. These micro machines being produced

in batch sizes of thousands at a time, with cost of individual unit nearing zero. Welcome

to the micro world, a place now occupied by a new technology known as MEMS, or more

simply, micro machines.

The word MEMS is an acronym for Micro-Electro-Mechanical System and generally

refers to the devices that are on a millimetre scale with micro-resolution. MEMS are the

integration of mechanical elements, sensors, actuators and electronics on common silicon

substrate through the utilization of micro fabrication technology. MEM promises to

revolutionize nearly every product category, thereby, making the realization of complete

system-on-a-chip.

In Microsystems, microelectronic integrated circuits (ICs) can be thought of as the

brains of system and MEMS augment this decision-making capability with eyes and

arms, to allow Microsystems to sense and control the environment. The sensor gathers

the information from the environment through measuring mechanical, thermal,

biological, chemical, optical, and magnetic phenomena. While the electronics process the

information derived from the sensors and through some decision making capability direct


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the actuators to response by moving, positioning, regulating, pumping, and filtering,

thereby, are controlling the environment for some desired outcome or purpose.

APPLICATION OF MEMS:

This recent explosion in interest in the MEMS area could have been, in part, a result of

the successful commercialisation of some high profile products like the Bubble Jet Printer

Head.

MICROSENSORS

BIOMEDICALAPPLICATIONS

Micro and RF Switches

OPTICALSWITCHING

MEMS-Based Optical Identification and Communication System (MOICS)TECHNICAL CHALLENGESTECHNICAL CHALLENGES:

Advanced simulation and modelling tools for MEMS design are

urgently needed;

The packaging of MEMS devices and systems needs to improve

considerably from its current primitive states;

MEMS device design must be separated from the complexities of

the fabrication sequences

MICROSENSORSMICROSENSORS:

There are quite selections of MEMS-based sensors that have been commercialised.

One of the more common applications of MEMS sensors comes in the form of an

accelerometer in the deployment of safety airbag in car. Some examples of MEMS

sensors include (a) pressure sensors, (b) strain gauges, and (c) accerolometer for the

measuring of acceleration and (d) gyroscope for the measurement of rotation.

The airbag deployment sensor is one of the earliest uses of MEMS sensors in cars.

Other possible use of the MEMS sensors includes the controlling of the amount of

vibration on a car using the accelerometer together with the suspension system. Also by

measuring the rotation of the car with the gyroscope, it is possible to judge whether the

driver is losing control of the car, and hence the deployment of the braking system.

Outside the car industry, the gyroscope can be used to check the rotations of essential


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machine parts so as to prevent critical failure. Examples would be in the turbine of

engine and power plants.

An used for activating the A Pressure Sensor with IC

integration

Airbag in Cars

BIOMEDICAL APPLICATIONS:

Another rapidly developing field of MEMS falls under the biomedical category. In this

area, MEMS have the great potential in (a) the Biomedical Instruments and Analysis, and

(b) Implants and Drug Delivery. Miniaturization of surgical and diagnostic instruments

are done for reasons like

Cost reduction

Less intrusive surgical procedures,

Health concerns,

Reducing amount of test sample needed, e.g. blood,

Speed of diagnosis,

Patient recovery time and,

Miniaturization of medical instruments is of interest for a number of reasons, dependent

on the application. In the case of surgical instruments, the decreasing size would mean a

less invasive operating procedure for patient, which also would mean a faster rate of

recovery for the patient. Furthermore, having micron-size instruments would mean that

previously untreatable complication pertaining to neural and cell repair is fast becoming a

thing of the past. Having the ability to shrink instruments to incredibly small sizes also

means that previously relatively unskilled personnel on Credit-Card size devices can do

time consuming and expensive diagnostic procedures. Similar in function to their room

size cousin but smaller in cost, these MEMS-based devices will be able to do things like


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DNA testing, blood testing and many more. And due to its size, only a small amount of

test sample is needed for the diagnosis and to top it off, the decreasing cost of the device

allows it to become disposable, hence reducing the chances of potential health hazard.

Another area of potential beneficial application of MEMS-based devices in the

biomedical field comes in the form of implants. The idea is to have a small drug-

dispensing device implanted into patients for the slow dispensing of drugs like

antibiotics, etc. This method of slow dispensing will even out the dosage of drugs in the

body as compared to that of popping pills and injections.

Micro sensors for Pneumatic Biosystems

Micro sensors for Chemical Biosystems

Impedance Sensors

Electrochemical Sensors

Molecular-Specific Sensors

Micromanipulators

Micro pumps, and Micro valves,

Micro filters, and Micro needles

Surgical Micro instruments

MEMS ENABLES FAST, RELIABLE OPTICAL SWITCHING:

Micro-mirrors are mirrors that have been "shrunk" down to the microscopic world.

Lately, the design and fabrication of micro-mirrors has received much more attention

than in the past. This is due to their ingenious application to the field of fiber optics. In


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any optical network, be it phone lines, small office networks, or large university

networks, most information is sent through optical fibre as beams of light that are either

on or off, depending upon whether the piece of information is a 1 or a 0 in binary form.

But, when the information needs to be re-routed (to a personal computer, for example)

the information transmission process becomes a little more complicated. A switching

station takes the incoming light beam, converts it into a digital signal, sends it to the fibre

that is going towards the PC, then converts it back into a light beam, as shown below.

This is all well and good, but what exactly does it have to do with micro-mirrors? Well,

wouldn't it be easier if, instead of having to convert the signal twice, one could simply

have the signal reflect off something, automatically sending it to its correct destination?

That's where micro-mirrors come in. By focusing the incoming light beam onto a micro-

mirror, the beam will reflect off of it and be sent into another fibre. If, however, the

micro-mirror has been actuated and is thus in an upright or slanted position, the incoming

beam will be sent to a different outgoing fibre. By utilizing many of these micro-mirrors

in sequence, all the incoming signals can be re-routed to their correct destination, without

ever having to be converted into a digital signal! This means a huge saving of time,

which corresponds to a higher network data transmission speed.


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Rotational structure.

APPLICATIONS:

Switching mechanism for photonic switches

Retinal scanning system

DWDM (MUX, DeMUX, Optical add/drop)

Optical Switches, Amplifiers, and Isolators

Variable Optical Attenuators

Wave guide to Fiber Coupling

TYPESOFMICROMIRRORS :

1D ARCHITECTURE

2D ARCHITECTURE

3D ARCHITECTUREWITHSCRATCHDRIVE

The 1-D architecture uses a mirror for each wavelength. A line array of micro

mirrors integrated with dispersive optics separates DWDM wavelengths. A simple digital

electronics an open loop configuration controls the micro mirrors. It uses a relatively

common manufacturing process compared to 2-D, 3-D architectures; hence the cost is

also considerably low.

A crossbar switch allows parallel communication 2D architecture actuators


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In 2-D architecture, a two dimensional array of micro mirrors is arranged in a single

plane. It can connect 'N' input fibers to 'N' outputs, hence also called N2 architecture

since it uses N2 micro mirrors to address 'N' channels. To establish a path between two

fibers, the corresponding mirror is activated while rest are disabled. All the light beams in

the in the switch reside on the same plane and hence the probability of insertion loss is

proportional to the port count.

2D architecture

The 2-D structure has limited scalability due to the chip size and the distance the

light must through the free space. As the port count increases, both the chip size and free

space travel will also grow as the square of the port count, resulting in an unacceptable

level of losses due to diffraction. For instance, 16-port micro mirror structure requires

256 microns and associated fibre alignment/consystems. The free-space beam

propagation distances among port-port switching are not a constant. Therefore in loss due

to Gaussian beam propagation is not uniform for all ports. A typical 16*16 switching

system suffers a loss of about 5 db.2-D optical switches are used in communication

networks that require smaller port size. Mirror control for 2-D switches is binary, hence

relatively 2-D switches is binary, hence relatively simple and straightforward. The

switches are digital since mirror position is bistable or on/off. Hence 2D type OXC is also

called digital OXC (OPTICAL CROSS CONNECT). Nearly all-micro mirror devices

shipping today are 2-D MEMS also posses a flexibility in functionality by arranging the

mirror differently. For instance these can be configured to function as arrays of 1*2, 2*2, N*M, 2*N, 1*N. The 2-D MEMS structure directly functions as a re-configurable

wavelength add-drop multiplexed (WADM).

The WADM consists of a wavelength de-multi-plexer separating the wavelengths from

the input fibre, switching them to different output fibers.

3D ARCHITECTURE2D ARCHITECTURE
http://images.google.co.in/imgres?imgurl=http://toshi.fujita3.iis.u-tokyo.ac.jp/home/research_project/2D%2520Mirror%2520Driver/2Dmirrormodel.JPG&imgrefurl=http://toshi.fujita3.iis.u-tokyo.ac.jp/home/research_project/2D%2520Mirror%2520Driver/2D_%20


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The 2-D MEMS type ADM have two rows of mirrors that operate simultaneously.

When mirror path is enabled, the incoming signal guided to the drop port and the

corresponding adds port is coupled to the output port. If the mirror is disabled, the light

signals travels straight from the input to the output port.

3-D MEMS, true engineering challenge, are known as the technology of the future. The

3-D micro mirror switch was first proposed in 1982 and its commercial version appeared

only 4-5 years ago.

3-D MEMS devices achieve photo ionic interconnection in three-dimensionsional space.

These use two degrees of freedom and can assume 'N' positions. The number of mirrors

required to route all the signals simultaneously is a 2N as opposed to N2 mirror in 2-D

architecture.An immediate advantage of 3-D architecture is that it can have port count

over 1000*1000. Since it can tilt freely about two axes, each operates in analogue mode

than binary modes in 2-D. Lucent's technology 3-D OXC using wave star Lambda router

uses continuously tilt angle greater than +or-6. In the year 2000,Nortel made the first ever

3-D OXC called X-1000 to beat the 1000 port barrier.

To attain multiple stable mirror positions, a closed loop servo system with feedback is

necessary for each mirror which in turn, warrants large size, high power consumption and

high cost. In addition like 2-D, it has to de-multiplex each wavelength oh the DWDM

before assigning an output port of the OXC and multiplex again for retransmission.

In spite of all these hurdles, 3-D MEMS scats hundred of ports in size and 1000 ports

switches are coming to the scene, though in such dense port all-optical switches might

never be necessary.

An altogether different approach in 3-D class micro machined mirror is the scratch drive

architecture proposed by AT&T Research Labs. Mirror based on SDA-type MEMS

switches respond very fast and the translational movement is extremely precise compared

to 3-D MEMS with two rotational axes.

SDA employs a couple of push rods to lift the mirror, is attached to them through micromachined hinges.

The translational movement of the translational plate is converted into a rotational

movement onto the mirror The number of bias pulses applied to the SDA determines the

plate translation distance and hence the degree of rotation the mirror with pushrods and

hinge joints. Like two-axes 3-D MEMS, the mirror can be rotated to multiple angles


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MEMS technology of this class is called free space micro-machined optical switch

(FSMOS).

MEMS-Based Optical Identification and Communication System

The MEMS-Based, Optical Identification and Communication System (MOICS),

technology, that can identify friend or foe (IFF) or relay data from sensors in hazardous

environments. MOICS comprises two types of components:

Remote units with MEMS CORNER CUBE REFLECTORS, which reflect

incident energy back to its source and can modulate the reflected signal

An interrogator unit, which sends a CODED OPTICAL LASER BEAM to locate and

request information from the remote units

The remote units will be small, lightweight, rugged, and environmentally sealed, and they

will require minimal power because the interrogator transmits the signal energy.

Moreover, they will not require expensive positioning systems because the interrogator

can be based on common laser range-finding technology.

Because MOICS operates at optical wavelengths, it can be eye safe, and the apertures for

both the interrogator and remote units can be very small. As a LOS optical system with a

low beam divergence, MOICS provides high angular and range resolution, thereby

assuring specific target identification. The small beam divergence combined with a high

data rate also makes MOICS a low probability of intercept (LPI) system. With

cryptographic coding, MOICS would be one of the most secure communications

capabilities on the battlefield.


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An electrostatic micro CCR: The movable base mirror is tilted when at rest. Applying a

voltage that pulls the mirror toward the substrate into a position orthogonal to the other

two mirrors can modulate incident light. CCRs of this design have a bandwidth ranging

from 0.2 to 2 kHz, with a driving voltage of 20 to 40 V. The key component ofMOICS, the

Tanner optical MEMS communication system, is the MEMS CCR (the micro-

electromechanical systems corner cube reflector). When its three mirrors are mutually

orthogonal, any incoming radiation is reflected directly back to the source. A CCR can

modulate the signaland thereby relay informationby tilting one of its mirrors.

Because the area of each CCR mirror will be less than 0.1 sq.mm, the remote units will

be very small. Our goal is to develop affordable MEMS CCRs that achieve MOICS

performance specs (e.g., a bandwidth of 100 kHz) and that can be easily assembled

MOICS COMMUNICATION:

This test bed demonstrates bi-directional half-duplex communication from an

interrogating transceiver (laser and photoreceptor) to a MOICS CCR unit and back. The

MEMS-Based Optical Identification and Communication System (MOICS) provide

secure bi-directional half-duplex communication between an interrogator unit and a

remote unit that includes a corner-cube reflector (CCR). First, the interrogator transmits a

modulated laser beam that encodes information (e.g., "Who goes there?"). The remote

unit demodulates and decodes the signal

Next, the interrogator transmits a modulated carrier beam (a raw uplink "supply" beam)

that impinges on the remote unit CCR. The remote unit controller toggles the base mirror

of the CCR, thereby adding further modulation ( ) and the remote unit data ( ) to the

beam reflected back to the interrogator. The interrogator extracts and decodes the data by

isolating signals with the carrier modulation ( ) from other light sources such as the sun,


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and isolating signals with the CCR modulation ( ), to filter out reflections of the laser

off of objects other than the CCR.

CONCLUSION:

Thus MEMS play an important role in the above-illustrated applications. Micro

machining and MEMS technologies are powerful tools for enabling the miniaturization of

devices useful in optical communication, biomedical engineering; MEMS based optical

identification and communication systems. MEMS give a highly reliable optical

switching.

mems and application

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