Download - Mems and Application
-
8/4/2019 Mems and Application
1/12
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] -
8/4/2019 Mems and Application
2/12
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
-
8/4/2019 Mems and Application
3/12
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
-
8/4/2019 Mems and Application
4/12
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
-
8/4/2019 Mems and Application
5/12
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
-
8/4/2019 Mems and Application
6/12
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.
-
8/4/2019 Mems and Application
7/12
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
-
8/4/2019 Mems and Application
8/12
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 -
8/4/2019 Mems and Application
9/12
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
-
8/4/2019 Mems and Application
10/12
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.
-
8/4/2019 Mems and Application
11/12
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,
-
8/4/2019 Mems and Application
12/12
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.