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MEMS1049

MechatronicsChapter 10

Actuators 10-1

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Actuators

Actuators

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Sensors and Actuators

Stimuli SENSORS Electric signal

Temp. PressureForce ChemicalRadiation, Acceleration

Stimuli ACTUATORS Mechanical Output

ElectricalMagneticThermalOptic

ForceDisplacementTorqueSpeed

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Example: Chemical Sensors

Chemical sensors are defined as measurement devices which utilize chemical or biological reactions to detect and quantify a specific analyte or event. They are usually a lot more difficult to make than physical sensors which measure physical parameters.

For the distinction between biosensors and chemical sensors we define a biosensor as one which contains a biomolecule (such as an enzyme, antibody, or receptor), a cell or even tissue as the active detection component.

A sensor, a transducer, transmitter and detector or often used as synonyms. They are devices that convert one form of energy into another and provide the user with a usable energy output in response to a specific measurable input. In the chemical sensor area a transducer plus an active surface is called a sensor.

Effector (magnetic, chemical, physical, etc.)

Active surface

Transducer

Amplification/Filtering/, etc

Data storage and processing

Output

Control

SensorIntegrated sensor

Smart sensor

Sensorsystem

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Sensing and actuation principles (6x6)

Example of Transduction Pr inciples

Output (Secondary Signal) Input (Pr imary Signal)

Mechanical (Mechano-)

Thermal (Thermo-)

Electr ical (Electro-)

Magnetic (Magneto-)

Radiant (Photo- or Radio-)

Chemical (Chemo-)

Mechanical Acoustics Fluidics

Friction calorimeter Cooling effects

Piezo electricity Piezo resistivity

Piezo magnetic effect

Photo- elasticity

Thermal Thermal expansion Bimetallic strip

Pyroelectricity Seebeck effect

Radiant emission

Reaction

Electr ical Piezoelectricity Electrometer

Joule heating, Peltier effect

Langmuir probe

Electro- luminescence

Electrolysis

Magnetic Magneto-striction Magnetometer

Thermo-magnetic

Magneto resistance

Radiant Radiation pressure

Thermopile Bolometer

Photo-electric Dember

Photo-reactions

Chemical Hygrometer

Calorimeter Thermal conductivity

Amperometry Flame ionization Volta effect

Nuclear magnetic resonance

Chemi- luminescence

e.g. piezoelectric

Mechanical

Electrical

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Sensing and actuation principles

Example: Piezoelectricity

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Sensing and actuation principles

Example: Photo-electro-mechanical coupling

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Techniques for Sensing and Actuation

Comparison of some major properties of mechanical sensing mechanisms used in micromachined devices

Common Sensing Methods– Piezo-resistivity– Piezoelectricity– Parallel plate capacitors (Capacitive Sensing)– Thermoelectricity– Others

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Techniques for Sensing and Actuation

Common Actuation Methods– Shape memory alloys– Piezoelectricity– Magnetostrictive– electrostatic– Thermal– Others

Table of linear actuator materials

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Actuator Example 1 Thermal Inkjet Printhead

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Inkjet Printhead

DRIVER

INK

PRINTHEAD

TECHNOLOGIES

Example 1 Thermal Inkjet Printhead

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Nozzles

Electrical contacts

Example: Thermal Ink Jet Printheads

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Monochrome cartridge1020, 1000, 1100, 2030, 3000, 2050Black = 56 nozzlesColor = 48 nozzles

2070 Black = 104 nozzlesColor = 96 nozzles

7000, 7200, 3200, 5000, 5700, Z51 (Excimer tech)Black = 208 nozzlesColor = 192 nozzles

Example: Inkjet Printhead---Nozzle Plates

Color Cartridge

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5700 Laser Crafted Nozzles (600x)

5700 Laser Crafted Nozzles (50x)

Nozzles Micro Photo

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Example: Thermal Ink Jet Printheads Power FETs

immersed in caustic ink

Nozzle Plate

Protective Overcoats

Conductor

Resistive Film

Thermal Barrier

Ink Drop

BubbleThermalRegion

To Paper

Nozzle

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Layers

A Semi Conductor Technology

Example 1 Thermal Inkjet Printhead

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STEP1: Initial conditions

STEP2: Resistor heated upon command and liquid vaporizes instantly causing a vapor bubble to form.STEP3: Vapor bubble grows to maximum size and ink ejected out of nozzle.STEP4: The bubble collapses and breaks off. Nozzle returns to initial condition.

1 2

3 4

Thermal - Bubble Formation

Example 1 Thermal Inkjet Printhead

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Actuator Example 2Piezoelectric Actuators

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Piezoelectric multilayer actuators

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Piezoelectric Cantilever Actuators

Vt

Ldz 22

31

23

= VLswtdF Ebl

11

31

83

−=

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Piezoelectric MEMS Devices

Silicon

Silicon NitridePZT

Passivation layerElectrodesConnection pads

Piezoelectric PZT-on-Si cantilever resonantor

Cantilever

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Piezoelectric Micropumps Pump

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Piezoelectric Printhead

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Piezo- actuator deforms when electrical pulseapplied

Example: Piezo Ink Jet

XeroxLexmark...

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Example: Piezo Ink Jet Printheads

– Shear mode

Using diced PZT ceramic shear mode actuators as ink chamber walls

Cover plate

Cover plate Fluid manifold

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Piezo Printheads

Three Types:

Using multilayer piezoelectric (PZT) ceramic actuator arrays

– Rod type.

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Piezo Printheads

– Chip type

Using bending mode PZT ceramic actuators arrays

substrate

nozzle

actuatorInk chamber

nozzle plate

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d31 Bending Actuators

PZT filmTi-Pt metal

SiO2

P++ Si membrane

EDP or KOH etched

Cross-Section of Ink Jet Piezo-actuators

Ink ChamberNozzlesNozzle plate

Si (110)

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Thermal Ink Jet vs Piezo Ink Jet Thermal

– Higher power required– High nozzle density– Ejectors very small,

approximately same size as drops

– Inexpensive to make Piezoelectric

– Low power consumption– Ejectors are large due to low

strain rates– Expensive to make Why Piezo- Printhead ?

Reliability♦ no excessive heating problem

Fast frequency response Low energy consumption Scalability Drop modulation Ink compatibility

Piezo-electric transducers

Thermal Heating

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Microactuators– ink droplet ejectors (printhead)– piezoelectric transformers– piezoelectric scanning tunneling microscope tip

Microsensors – accelerometers– micro-resonators– surface acoustic wave (SAW) devices– underwater acoustic imaging sensors

Piezoelectric actuators and sensors

Performance Criteria – Actuators

generative force/momentumdisplacement frequency response

– Sensors sensitivity frequency response stability or repeatability

MEMS1049ActuatorsSensors and Actuators Example: Chemical Sensors Sensing and actuation principles (6x6)Sensing and actuation principlesSensing and actuation principlesSlide Number 8Slide Number 9Slide Number 10Inkjet PrintheadExample: Thermal Ink Jet Printheads Example: Inkjet Printhead---Nozzle PlatesNozzles Micro PhotoExample: Thermal Ink Jet Printheads A Semi Conductor TechnologyThermal - Bubble FormationSlide Number 18Piezoelectric multilayer actuatorsPiezoelectric Cantilever ActuatorsPiezoelectric MEMS DevicesSlide Number 22Slide Number 23Example: Piezo Ink JetExample: Piezo Ink Jet PrintheadsPiezo PrintheadsPiezo Printheadsd31 Bending ActuatorsThermal Ink Jet vs Piezo Ink JetPiezoelectric actuators and sensors