Department of Instrumentation & Control Engineering, MIT, Manipal

Lecture #03

MEMS & Micro Systems

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Department of Instrumentation & Control Engineering, MIT, Manipal

Contents

1. Micro Sensors & Actuators

2. Components of Microsystems

3. Comparison of ME & MST

4. Intelligent Microsystems

5. Further

6. Successful Devices

7. Principle Science

8. Animation Demo

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Micro Sensors & Actuators

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� The core element in MEMS generally consists of two principalcomponents: a sensing or actuating element and signal transduction unit.

� MEMS as a microsensor:

� Micro sensors are built to sense the existence and the intensity of certainphysical, chemical or biological quantities, such as temperature, pressure,force, sound, light, nuclear radiation, magnetic flux and chemicalcompositions.

� Common sensors include biosensors, chemical sensors, optical sensors,thermal and pressure sensors.

S.Meenatchisundaram, Department of Instrumentation & Control Engineering, MIT, Manipal

Micro Sensors & Actuators

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� MEMS as a microactuators:

� The transduction unit converts the input power supply into the form such asvoltage for a transducer, which functions as the actuating element.

� There are several ways by which microdevice components can be actuatedsuch as electrostatic forces.

S.Meenatchisundaram, Department of Instrumentation & Control Engineering, MIT, Manipal

� A microsystem is an engineering system that contains MEMS componentsthat are designed to perform specific engineering functions.

� Usually a microsystem will be in meso-scale even though the MEMScomponents can be produced in microns.

� A microsystem includes three major components of micro sensors,actuators and a processing unit as shown in figure.

Components of Microsystems

5S.Meenatchisundaram, Department of Instrumentation & Control Engineering, MIT, Manipal

� One popular actuation method involves electrostatic forces generated bycharged parallel conduction plates, or electrodes separated by a dielectricmaterial such as air.

� The arrangement is similar to that of capacitors.

� The application of input voltage to the plates (i.e., the electrodes in acapacitor) can result in electrostatic forces that prompt relative motion ofthese plates in normal direction of aligned plates or parallel movement formisaligned plates.

� These motions are set to accomplish the required actions. It is used in manymicroactuators such as microgripper.

Components of Microsystems

6S.Meenatchisundaram, Department of Instrumentation & Control Engineering, MIT, Manipal

Components of Microsystems

7S.Meenatchisundaram, Department of Instrumentation & Control Engineering, MIT, Manipal

� Most microsystems are designed and constructed to perform singlefunctions. Incorporating signal processing and closed loop feedback controlsystems in a microsystem makes the integrated system as “intelligent”systems.

Intelligent Microsystems

8S.Meenatchisundaram, Department of Instrumentation & Control Engineering, MIT, Manipal

Intelligent Microsystems

9S.Meenatchisundaram, Department of Instrumentation & Control Engineering, MIT, Manipal

S.Meenatchisundaram, Department of Instrumentation & Control Engineering, MIT, Manipal

Microelectronics Micro system Technology

Uses Single Crystal Silicon (SCS)

die, Si compounds.

Uses SCS die and GaAs, quartz,

polymers and metals

Stationary structures May involve moving components

Primary 2D structures

Fewer components in assembly

Complex 3D structures

Many components to be assembled.

Mature IC design methodologyLack of engineering design

methodology and standards

Manufacturing techniques are

proved and well documentedDistinct Manufacturing techniques

Packaging technology is well

established

Packaging Technology is at the

infant stage.

Comparison of ME & MST

10S.Meenatchisundaram, Department of Instrumentation & Control Engineering, MIT, Manipal

� Working Principle based on Applications

� Materials

� Process

� Basics of Mechanics

� Design of MEMS Devices

Further

11S.Meenatchisundaram, Department of Instrumentation & Control Engineering, MIT, Manipal

� Micro Gear: A gear made with ceramics, pitch of the gears in the order of100 microns is shown in figure. Made by a process called LIGA.

Successful Devices

12S.Meenatchisundaram, Department of Instrumentation & Control Engineering, MIT, Manipal

� Micro Motor: An electrostatic driven micromotor produced by LIGAprocess is shown in figure. All three components – the rotor (center gear),the stator, and the torque transmission gear are made of nickel. The toothedrotor’s dia is of 700 microns and the gear is 250 microns dia. The gapbetween rotor and stator is 4 microns. The height of the unit is 120 microns.

Successful Devices

13S.Meenatchisundaram, Department of Instrumentation & Control Engineering, MIT, Manipal

� Micro Turbine: A microturbine was produced to generate power made ofnickel in 1993 as shown in figure. The unit height is 150 microns and amaximum rotational speed 1,50,000 revolutions per minute with a lifetimeup to 100 million rotations.

Successful Devices

14S.Meenatchisundaram, Department of Instrumentation & Control Engineering, MIT, Manipal

� Micro Switch: These components are extensively used for high speedsignal transmission. Micro optical switches are used to regulate incidentlight from optical fibers to appropriate receiving optical fibers.

Successful Devices

15S.Meenatchisundaram, Department of Instrumentation & Control Engineering, MIT, Manipal

� Principle science and engineering disciplines involved in micro systemdesign and manufacture is shown in the figure.

Principle Science

16S.Meenatchisundaram, Department of Instrumentation & Control Engineering, MIT, Manipal

Animation Demo

17S.Meenatchisundaram, Department of Instrumentation & Control Engineering, MIT, Manipal

3D_stack Accelerometer

Demo

Accelerometer

Demo

DLP Demo

RF Switch

Demo

Coventorware

DemoCantilever Switch

Demo