MEMS APPLICATIONS
OVERVIEW
Force-balance accelerometer
used for microgravity
measurements.
Macro (top) vs. MEMS (bottom)
[Courtesy of NASA]
MEMS Applications Overview Learning Module
Unit Overview
Microelectromechanical systems (MEMS) are
very small devices or groups of devices that
can integrate both mechanical and electrical
components.
This unit provides a brief summary of MEMS
devices already on the market. It also
discusses the various fields in which MEMS
are used and the possibilities for MEMS in
these fields.
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Objectives
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State three fields in which MEMS devices are
being used
State three applications of MEMS devices in
the automobile industry
State three applications for MEMS in the
medical field
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What is a MEMS?

MEMS are constructed on one chip with
electrical circuitry for inputs and outputs
of the electromechanical components.

MEMS can consist of a combination of
components in various scales: nano,
micro, and milli.

An example is the MEMS artificial retina.
This MEMS consists of an electrode
microarray (shown in picture) that is
placed on the retina inside the eye.
Prototype of a MEMS Retina Implant
[Photo by Randy Montoya. Courtesy of Sandia
National Laboratories]
This microarray interfaces with external components (a camera and
microprocessor contain in the patient’s glasses) and the brain (via the optic
nerve). The camera image is converted into a series of electrical pulses that
are sent to the brain from the microarray via the optic nerve. The brain
translates these pulses into flashes of light for a low resolution image.
This MEMS has been tested and IT WORKS! (Check out next slide)
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Retinal Prosthesis: What the patient sees
Images generated by the DOE-funded
Artificial Retinal Implant Vision
Simulator devised and developed by Dr.
Wolfgang Fink and Mark Tarbell at the
Visual and Autonomous Exploration
Systems Research Laboratory, California
Institute of Technology.
[Printed with permission.]
These images show what a patient with a MEMS retinal prosthesis should see.
Increasing the number of electrodes in the retina array results in more visual
perceptions and higher resolution vision.
In 2007 six patients were successfully implanted with the first prototype Model
1 device or Argus I™ containing 16 electrodes (16 pixels - left picture).
The Argus II™ (almost 200 pixels) proved successful in phase two of clinical
trials. Patients could find doorways, distinguish colors and even read!
The third model (256 pixels – middle picture) is under development and trials
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are projected for 2011.
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MEMS Scale – Pressure Sensors (PS)
A pressure sensor is a device consisting of a mechanical component
(diaphragm) and electronic components.
These pictures compare a macrosize pressure sensor (70mm in
diameter) to a MEMS pressure
sensor.
The left picture compares both
systems. The right hand pictures
compare the diaphragms. The
MEMS diaphragm is being seen
through a microscope.
[Macro PS photos courtesy of Bob Willis
MEMS diaphragm courtesy of UNM/MTTC]
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To create a MEMS PS the
diaphragm and related electrical
components are reduced in size
and placed on a microchip as
illustrated in the insert on the left
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picture.
What are MEMS?
MEMS devices sense, think, act and communicate.
They redirect light, pump and mix fluids, and detect molecules, heat,
pressure, or motion.
The interaction of electronics, mechanics, light or fluids working
together makes up a microelectromechanical system or MEMS.
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Applications of MEMS
Applications are developed where miniaturization is beneficial:

Consumer products

Aerospace

Automotive
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Biomedical
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Chemical

Optical displays
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Wireless and optical communications

Fluidics
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Types of MEMS Devices
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Pressure sensors
Accelerometers (inertial
sensors)
Micromirrors
Gear Trains
Miniature robots
Fluid pumps
Microdroplet generators
Optical scanners
Probes (neural, surface)
Analyzers
Imagers
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MEMS Sensors
Sensors are a major application for MEMS devices.
Three primary MEMS sensors

pressure sensors

chemical sensors

inertial sensors (accelerometers, gyroscopes)
MEMS sensors can be used in combinations with other sensors
for multisensing applications. For example, a MEMS can be
designed with sensors to measure the flow rate of a liquid
sample and at the same time identify any contaminates within
the sample.
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MEMS Pressure Sensor

MEMS pressure sensors use a
flexible diaphragm as the
sensing device.

One side of the diaphragm is
exposed to a sealed, reference
pressure and the other side is
open to external pressure.

The diaphragm moves with a
change in the external pressure.
MEMS Pressure Sensor
[Courtesy of the MTTC, University of New
Mexico]
What are some possible applications for this type of sensor?
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MEMS in the Automotive Industry
MEMS pressure sensors
sense, monitor and transmit
 Tire pressure
 Fuel pressure
 Oil pressure
 Air flow
 Absolute air pressure
within the intake manifold
of the engine
What other applications are possible
within the automotive industry?
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MEMS in the Automotive Industry
MEMS pressure sensors
sense, monitor and transmit
 Tire pressure
 Fuel pressure
 Oil pressure
 Air flow
 Absolute air pressure
within the intake manifold
of the engine
What other applications are possible
within the automotive industry?
Air-bag deployment, throttle position, weight and sensing of passengers
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Pressure Sensors in BioMedical Applications
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Blood PS
Intracranial PS
PS in endoscopes
Sensors for infusion pumps
RF (radio frequency) elements
incorporated into the MEMS device
allow the sensor to transmit its
measurements to an external receiver.
What are some other possibilities for
MEMS PS in the medical field?
MEMS Blood Pressure Sensors on the
head of a pin. [Photo courtesy of
Lucas NovaSensor, Fremont, CA]
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Other Pressure Sensor Applications

Barometric PS - used in wind tunnels
and for weather monitoring applications.
(see picture)

"Smart Roads" - millions of MEMS
sensors are incorporated into roads to
gather and transmit information about
road conditions. (“MEMS Applications:. All About MEMS. 2002.
http://www.allaboutmems.com/memsapplications.html)

Smart Dust is a network of micro-sized
wireless MEMS sensors that
communicate with each other through
tiny transmitters. Smart dust sensors
(such as MEMS pressure sensors) could
be scattered around a building, a piece
of property, embedded in clothing, or in
road beds. (“SMART DUST - Autonomous sensing and
Barometric Pressure Sensors
(Photo courtesy of Khalil Najafi,
University of Michigan)
communication in a cubic millimeter". Dr. Kris Piser, PI. DARPA/MTO MEMS
Program, Berkley.)
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Brainstorming
Let’s do a little brainstorming for other applications of
MEMS pressure sensors.
There are other fields we didn’t discuss, so think
beyond automotive and medical. What about
aerospace, environmental, military, sports, or
consumer gaming?
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MEMS Inertial Sensors
Newton's First Law of Motion (also referred to as the law
of inertia) states, "An object at rest tends to stay at rest
and an object in motion tends to stay in motion with the
same speed and in the same direction unless acted
upon by an unbalanced force.”
MEMS inertial sensors are designed to sense a change
in an object's inertia, and then convert, or transduce
inertial force into a measurable signal. They measure
changes in acceleration, vibration, orientation and
inclination. This is done through the use of micro-sized
devices called accelerometers and gyroscopes.
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MEMS Accelerometers
MEMS Accelerometer
[Photo courtesy of Khalil Najafi, University of
Michigan]
The simplest MEMS accelerometer sensor is an inertial mass
suspended by springs.
The mass is deflected from its nominal position as a result of
acceleration. This deflection of the mass is converted to an
electrical signal as the sensor's output.
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MEMS Gyroscopes
A gyroscope is generally a spinning wheel or disk with a free
axis allowing it to take any orientation (below left). Some MEMS
gyroscopes use a vibrating structure rather than the traditional
rotating disk to determine orientation (see bottom right).
MEMS Vibrating Ring Gyroscope
[(Photo courtesy of Sandia National Laboratories]
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MEMS Inertial Sensors in Automobiles
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Airbag deployment
"Smart" sensors for collision
avoidance and skid detection
Active suspension
Automobile navigation
Antitheft system
Headlight leveling and
positioning
Rollover detectors
Polysilicon Connectors
3-axis High-Performance Micromachined
Accelerometer
(Each accelerometer senses movement in one
direction. Notice the markings: x-y-z. The
accelerometers are connected using polysilicon
connectors.)
[Image courtesy of Khalil Najafi, University of Michigan]
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Airbag Deployment Sensor
The type of inertial sensor used in
air-bags is called a shock sensor
using 3 accelerometers.
The sensor has an accelerometer
for each orthogonal direction (x, y,
and z) and corresponding
circuitry.
Compared to the macro device, a
MEMS provides a quicker
response to rapid deceleration
and more reliable functionality. It
is cheaper and smaller in size.
3-axis Accelerometer for airbag deployment
[Courtesy of Sandia National Laboratories]
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Other Applications of MEMS Inertial Sensors
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Motion and shock detection
Vibration detection and
measurement
Measurement of tilt and inclination
Anti-theft devices
Home security devices
Computer screen scrolling and
zooming devices
Gaming devices for portables and
PC's (e.g. Wii and Playstation)
Image stabilizer cameras and
phones
MEMS Vibrating Gyroscope
[(Photo courtesy of Sandia National
Laboratories]
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Other Types of MEMS
In addition to sensors, MEMS consist of pumping devices, gear
trains, moveable mirrors, miniature robots, tweezers, tools and
lasers.
These devices have found numerous applications with various fields
such as biomedical, optical, wireless networks, aerospace, and
consumer products.
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MEMS in the Medical Field
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Precise dispensers for small
amounts of liquids found in
needleless injectors and drug
delivery systems.
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Sub-dermal glucose for monitoring
monitor glucose levels and deliver of
the insulin. (See figure)
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Medical diagnostics for blood
analysis, cells counts and urinalysis.
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Polymerase chain reaction (PCR) for
DNA replication.

DNA microarrays for testing of
genetic diseases and other
biological markers.
MiniMed Paradigm[R] 522 insulin pump, with
MiniLinkTM] transmitter and infusion set.
A chemical sensor (C) measures the blood glucose
and a transmitter (D) that sends the measurement to
the a computer in (A). (A) also contains a
micropump that delivers a precise amount of insulin
through the cannula (B) to the patient. This is a
continuous bioMEMS monitoring and drug delivery
system.
(Printed with permission from Medtronic Diabetes)
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Clinical Laboratory Testing
The picture to the right shows a lab-on-achip (LOC). This device literally takes the
laboratory testing of biomolecular samples
(e.g. blood, urine, sweat, sputum) out of the
typical medical lab and places it in the field
and even at home.
Using microfluidics and chemical sensors,
this MEMS or bioMEMS can
simultaneously identify multiples analytes
(substances being analyzed).
An example of a home LOC is the home
pregnancy test. This bioMEMS uses a
reactive coating that identifies a specific
protein found in the urine of pregnant
women.
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Lab-on-a-chip (LOC)
Printed with permission. From
Blazej,R.G.,Kumaresan,P. and Mathies, R.A.
PNAS 103,7240-7245 (2006).
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Other Biomedical Applications
What are some other current and potential
applications of MEMS in the medical field?
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Optical Applications of MEMS
The objective for optical MEMS is to integrate optical, mechanical
and electronic functions into one device. Optical MEMS have
already been quite successful in display technologies.
Two commercial devices – Digital Mirror Devices and Grating Light
Valve - redirect light to create high definition imaging from digital
signals. Both of these devices are used in video projection
systems such as rear and front projection televisions.
Texas Instrument's Digital Mirror Devices (DMD) have been
used for several years in a variety of projection systems
including video projection and digital cinema. The
technology is called digital light processing or DLPTM, a
trademark owned by Texas Instruments, Inc.
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TI’s DLP (digital light processing) System
Levels of a DMD Array (left) and How a DLP system works (right).
[Images Courtesy of Texas Instruments]
A DMD is an array of micromirrors (left figure). Each micromirror (between 5um
and 20um square) is designed to tilt into (ON) or away from (OFF) the light source.
The mirror tilts when a digital signal energizes an electrode beneath the mirror.
One mirror can be turned OFF and ON as many as 30,000 times per second.
There are thousands of mirrors in an array with less than 1 μm spacing between
them. The DLP 1080p technology delivers more than 2 million pixels for true
1920x1080p resolution. The diagram on the right illustrates how the DLP system
works
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The Grating Light Valve (GLV)
The GLV device developed by Silicon Light
Machines, is another micro optical based system.
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This microdevice consists of several silicon
nitride ribbons coated with aluminum. A set of
four ribbons (two fixed and two moveable)
produce a 20 μm square pixel.
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The ribbons are held "up" by the tensile
strength of the material (silicon nitride and
aluminum).

The moveable ribbons are "moved" up and
down electrostatically. Electrodes are placed
under the moveable ribbons. Variable voltages
applied to the electrodes pull the ribbons down.
When no voltage is applied, the tensile
strength of the ribbon will allow it to snap back.

GLVs are used in high definition TVs and are
being investigated for use in maskless
photolithography.
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Grating Light Valve (GLV) – top view and side view
showing actuated state and unactuated state
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Other Optical Applications of MEMS
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Optical Communication Networks
Tunable lasers and filters
Display screens on cell phones and
PDAs
Variable optical attenuators
Optical Spectrometers
Bar code readers
MEMS micromirror arrays are the key
components for optical communication
networks. The micromirrors act as
switches directing light from a fiber optic
to a specific output port by moving up and
down, left to right or swiveling to a desired
position.
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MEMS Pop-up mirror for optical applications.
Notice the hinge allowing for the different
angles needed to direct light in different
directions. Also notice the track that assists in
positioning the mirror at the correct angle.
[Image Courtesy of Sandia National
Laboratories
TM
SUMMIT Technologies,
www.mems.sandia.gov]
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Other Applications of MEMS

MEMS nozzles and pumps
for inkjet printers
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RF devices – Switches,
phase shifter resonators,
filters and variable antennas

Fuel delivery systems that
can control propellant
motion

Coating sensors that
compensate for coating
problems (adhesion, surface
tension)
MEMS-based InkJet Printhead
Piezoelectric or bubble jet based injection methods
meeting the demand for higher and better resolution
printing (smaller droplets). The graphic below illustrates a
piezoelectric printhead. When a voltage is applied across
the piezoelectric crystal, a minute amount of ink is
released into the nozzle.
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MEMS Microgrippers
Zyvex Microgrippers
[Printed with permission © 2002 Zyvex]
Grippers or tweezers used in a variety of fields to clasp, pick up,
and move micron to nanosize components. The microgrippers
(50 microns thick), developed by Zyvex Corporation, pick and
place other microdevices in an automated microassembly
process. The gripper on the left opens to 100 microns. The
gripper on the right opens to 125 microns.
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Review
What type of MEMS device(s) could be used for
the following applications?
 Wii hand controller
 Detect
the presence of a specific molecule
(chemical or biological)
 Transmit
data in a digital communications
network
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Review
What type of MEMS device(s) could be used for
the following applications?
 Wii hand controller
 Inertial
sensor (accelerometer and/or gyroscope)
 Detect
the presence of a specific molecule
(chemical or biological)
 Chemical
 Transmit
sensor
data in a digital communications
network
 MEMS
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mirrors that can rotate, bend, turn
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Summary
The automotive industry was one of the first
industries to embrace the use of MEMS.
Since then, MEMS have found applications
in wireless communications, biomedical,
aerospace, and consumer products (to
name a few).
The potential uses for MEMS are endless.
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Acknowledgements
Copyright 2009 – 2011 by the Southwest Center for Microsystems
Education and The Regents of the University of New Mexico.
Southwest Center for Microsystems Education (SCME)
800 Bradbury Drive SE, Suite 235
Albuquerque, NM 87106-4346
Phone: 505-272-7150
Website: www.scme-nm.org email contact: mpleil@unm.edu
The work presented was funded in part by the National Science
Foundation Advanced Technology Education program, Department of
Undergraduate Education grants: 0830384 and 0402651.
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