UNIT-1 MEMS 5th sem.
Unit 1 MARKS: 15
INTRODUCTION TO MICRO SYSTEM AND SMART SYSTEMS
The term MEMS is an abbreviation of micro electro mechanical system. MEMS contain
components of size 1 micrometre to 1 millimetre. Any engineering system that performs
electrical and mechanical functions with components in micrometres is MEMS.
In the most general form, MEMS consist of mechanical microstructures, micro sensors, micro
actuators and microelectronics, all integrated onto the same silicon chip. This is shown
schematically in Figure 1.
Components of MEMS
MEMS generally consist of two components: a sensing or actuating element and a
signal transduction unit. Figure shows the relationship between these two components.
Figure 2 MEMS as micro sensor
MEMS as micro sensor
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UNIT-1 MEMS 5th sem.
Micro sensor are built to sense the existence and intensity of certain physical,
chemical or biological quantities such as temperature ,pressure, force, sound ,light
,chemical compositions etc. Micro sensors have advantages of being sensitive and
accurate with minimal amount of required sample substance.
Ex. Acoustic wave sensors, Biomedical and biosensors, Chemical sensors, Optical
sensors, Pressure sensors, Stress sensors, Thermal sensors etc.
MEMS as micro actuator
Figure 3 shows the functional relationship between actuating element and the
transduction unit in a micro actuator. An Actuators usually covert input energy into
controlled mechanical energy. Actuators use input energy and release output energy in
a controlled manner.
Ex. Grippers, tweezers and tongs Motors - linear and rotary Relays and switches
Valves and pumps Optical equipment
Figure 3 MEMS as micro actuator
MICROSYSTEM
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UNIT-1 MEMS 5th sem.
A microsystem is an engineering system that contains MEMS components that are
designed to perform specific engineering functions.
3 components of micro systems are
Micro sensors
Actuators
A processing unit
An airbag deployment system, Microfluidics, e.g. Capillary Electrophoresis (CE), Micro
accelerometers (inertia sensors)
Microsystems = sensors + actuators + signal transduction:
Figure 4 components of microsystem
Smart system
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UNIT-1 MEMS 5th sem.
Smart systems incorporate functions of sensing, actuation, and control in order to
describe and analyse a situation, and make decisions based on the available data in
a predictive or adaptive manner, thereby performing smart actions.
Smart systems typically consist of diverse components:
Sensors for signal acquisition
Elements transmitting the information to the command-and-
control unit
Command-and-control units that take decisions and give
instructions based on the available information
Components transmitting decisions and instructions
Actuators that perform or trigger the required action
Examples of Smart System
• Air Conditioning system
• Automatic Washing Machine
• Smart phones
• Smart toys
Figure 5 components of Smart system
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UNIT-1 MEMS 5th sem.
System –on-a-chip
A system on a chip (SoC) is an integrated circuit (also known as a "Lab on chip") that
integrates all or most components of a computer or other electronic system. These
components almost always include a central processing
unit (CPU), memory, input/output ports and secondary storage – all on a single substrate or
microchip, the size of a coin. It may contain digital, analog, mixed-signal, and often radio
frequency signal processing functions . SoCs are in contrast to the common traditional
motherboard-based PC architecture, which separates components based on function and
connects them through a central interfacing circuit board.
SoCs are in contrast to the common traditional motherboard-based PC architecture,
which separates components based on function and connects them through a central
interfacing circuit board.
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UNIT-1 MEMS 5th sem.
Application of MEMS and Microsystems in Automotive Industry
• Safety
Airbag system
Antilock breaking system
Suspension system
Object avoidance
Navigation (micro gyroscope)
• Engine and power train
Manifold control with pressure sensors
Airflow control
Exhaust gas analysis and control
Crankshaft positioning
Transmission force and pressure control
• Comfort and convenience
Seat control
Riders comfort
Security sensors
Sensors for defogging of windshields
Satellite navigation sensors
• Vehicle diagnostics and health monitoring
Engine coolant temperature and quality
Engine oil pressure, level and quality
Tyre pressure
Brake oil pressure
• Telematics, e.g. GPS, etc.
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UNIT-1 MEMS 5th sem.
Application of MEMS and Microsystems in Aerospace Industry
Cockpit instrumentation.
•Sensors and actuators for safety - e.g. seat ejection
Wind tunnel instrumentation
Sensors for fuel efficiency and safety
Microsatellite’s
Command and control systems with MEMtronics
Inertial guidance systems with micro gyroscopes, accelerometers and fiber optic
gyroscope.
Attitude determination and control systems with micro sun and Earth sensors.
Power systems with MEMtronic switches for active solar cell array reconfiguration,
and electric generators
Propulsion systems with micro pressure sensors, chemical sensors for leak detection,
arrays of single-shot thrustors, continuous microthrusters and pulsed microthrousters
Thermal control systems with micro heat pipes, radiators and thermal switches
Communications and radar systems with very high bandwidth, low-resistance radio-
frequency switches, micromirrors and optics for laser communications, and micro
variable capacitors, inductors and oscillators.
Application of MEMS and Microsystems in Biomedical Industry
Disposable blood pressure transducers: Lifetime 24 to 72 hours; annual production 20
million units/year, unit price $10
Catheter tip pressure sensors
Sphygmomanometers
Respirators
Lung capacity meters
Barometric correction instrumentation
Medical process monitoring
Kidney dialysis equipment
Micro bio-analytic systems: bio-chips, capillary electrophoresis, etc.
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UNIT-1 MEMS 5th sem.
Application of MEMS and Microsystems in Consumer Products
Scuba diving watches and computers
Bicycle computers Sensors for fitness gears
Washers with water level controls
Sport shoes with automatic cushioning control
Digital tire pressure gauges
Vacuum cleaning with automatic adjustment of brush beaters
Smart toys
Application of MEMS and Microsystems in the Telecommunication Industry
Optical switching and fiber optic couplings
RF relays and switches
Tunable resonators
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UNIT-1 MEMS 5th sem.
Engineering disciplines involved in Micro system Design, Manufacture & Packaging.
Five engineering disciplines are involved in Micro system Design, Manufacture &
Packaging.
1. Mechanical engineering principles are used primarily in the design of microsystem
structure and packaging of the components. Intelligent microsystem has not been well
developed but it is an essential part of micro mechatronics systems, which are defined
as intelligent micro electro mechanical system.
2. Electrical engineering involves electrical power supplies and the functional control
and signal processing circuit design. For integrated micro systems, e.g. ‘laboratory-
on-a-chip’, the IC and microelectronics circuitry that integrates microelectronics and
micro system makes electrical engineering a major factor in Design, Manufacture &
Packaging.
3. Chemical engineering is an essential component in fabrication and micro
manufacturing .Almost all such process involve chemical reactions. Some micro
device packaging techniques also rely on special chemical reactions.
4. Material engineering offers design engineers a selection of available materials that
are amenable to micro fabrication and manufacturing as well as packaging. Theories
of molecular physics are often used in the design of materials characteristics.
5. Industrial engineering relates to the production and assembly of microsystems.
Optimum design of the fabrication process and control is essential in micro system
productionn.
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