L2 Sensor Introd

1

METR3100: Sensor Introduction

http://www.mech.uq.edu.au/courses/metr3100/

Sensor Introduction

Han HuangRoom 45-212; Phone: 3365 3583

[email protected]

METR3100: Sensors and Actuators


Introduction to sensors

– What is a sensor?– What will we learn?– “Future” sensors:

MEMS based sensorsMEMS based sensors

2


What is a sensor?

• Formal definition: “A device that receives and responds to a signal or stimulus”– American Heritage Dictionary of the English Language

• Informally, a sensor is a device that takes in information from the outside world. Based on the information, the sensor creates a signal on which a system can make a decision.

• A sensor, thus, has an input and an output


What is a sensor? (cont.)

• A sensor will measure some physical quantity and convert it into some electrical signal (e.g., voltage)

• You would also want to do something intelligent based on the signal (turn on a heater, sound an alarm, pass/fail an industrial part, etc)

Sensor RecordingSystem

electrical signal

physical parameter

3


Sensor Characteristics

• What are some important quantities of a sensor?

–Sensitivity, Resolution–Accuracy, Precision–Repeatability, Reliability–Response function–Dynamic range–Noise characteristics–Uncertainty


Sensing Systems

What advantages do sensors have over using a humanWhat advantages do sensors have over using a human?

• Repeatability - sensor output is very stable over time whereas a human may suffer from fatigue

• Reliability - a sensor usually won’t need breaks, vacations…

• Harsh environments - a sensor can operate in many environments that humans may not

• Sensitivity - sensors can be more sensitive than the corresponding human sense

4


Reliability Issue of Testing – A True Story


What will we learn?

Sensing systems– Temperature– Pressure– Strain– Force and torque– Displacement and transport– Vibration– Air pollution

Also including– Amplifiers and signal conditioning– Data acquisition and processing

5


MEMS based sensorsMEMS based sensors

“Future” Sensors


What is a MEMS sensor?

• Microelectronic integrated circuits that have changed our lifestyle in the past two decades can be imagined as the "brains" of a system and MEMS augments this decision-making capability with "eyes“ and "arms", to allow the system to sense and control the environment.

• A sensor is described as “eyes” or “ears” or “nose”…

6


What is MEMS

• MEMS refers to micro-electro-mechanical systems

• Tiny mechanical devices built onto semiconductor chips

• MEMS typically combine two or more properties on a single microchip, such as electrical, mechanical, biological, magnetic, optical or chemical properties

• Most MEMS generate or sense motions (like actuators, mirrors and cantilevers)


MEMS Applications : Automotive

• Today there are ??? sensors in one car

• Applications:- engine monitoring- safety- comfort- navigation

• Radio-Frequency MEMS (RF MEMS)

• RADAR

• Parking help Courtesy of Polytec

50 to 100

7


Air intake, brakes, turbo pressure, tire pressure, fuel injection, …

Pressure sensors

Fuel injectionMicro Nozzles

Wheel speed, pedal position, steering wheel angle

Magnetic sensors

Heating Ventilation Air Conditioning, oil condition

Chemical, humidity sensors

Access controlBiometric sensors

Airbag, Vehicle Dynamic Control, rollover sensing, GPS

Accelerometers, Gyroscopes

ApplicationsDevices


Aerospace and Defence

Courtesy of Polytec

8


Radio communicationRF MEMS

Altitude controlPressure sensors

Communication and inter satellite optical link

Micro displays, Micro mirrors

Monitoring of pilot’s breathing, supersonic flow

Flow sensor

Detection of chemical / biological weapons

Chemical sensors, Biochips

Inertial navigationAccelerometers, Gyroscopes, Magnetometers

ApplicationsDevices


Reasons of using MEMS

• Low energy consumption• Low weight• Very small size• Low cost at high volumes

(more automotive applications)

• New functionalities

Airbag sensor (Toyota): US$50 to US$7

9


Toyota's surface micromachined piezoresistive micro diaphragm pressure sensor (Shimaoka et al. 1993).

Toyota 32 x 32 (1K)-element piezoresistive pressure/tactile sensor array (Sugiyama et al. 1990).

Pressure Sensor


According to a report from Venture Development According to a report from Venture Development Corporation (Natick, MA), automotive market will Corporation (Natick, MA), automotive market will represent 5.2 percent of the overall $34.2 billion represent 5.2 percent of the overall $34.2 billion

MEMS market in 2006 or more than $1.7 billion, up MEMS market in 2006 or more than $1.7 billion, up from $1.1 billion in 2001.from $1.1 billion in 2001.

Conventional air bag pressure sensor device: Conventional air bag pressure sensor device: US$50US$50. . MEMS based pressure sensor and device: MEMS based pressure sensor and device: US$7US$7

The Impact

10


Gyroscope• It took five years to develop gyroscopes

• Introduced on the market in 2000

• Now several millions are produced every year by Robert Bosch GmbH


Pressure sensor

• Sensor Orbital Research Inc. develops a MEMS-based high temperature pressure transducer technology for diesel and turbine engine applications. • Based on a thin film strain gage configuration using MEMS fabrication techniques and a highly sensitive, novel thin-film material . • The technologies combine synergistically resulting in a unique, high temperature sensor with high sensitivity at an affordable price . • Have high gage factor (sensitivity ) and high temperature capability is significantly greater than competing technologies. • Demonstrated in the harsh diesel engine environment (reliability )

11


High Temperature Pressure Sensor

Orbital Research Inc.

Pressure Ranges: 0-60, 0-1000, 0-3000, psi Operating Temperature: 400 oC for Diesel Engines - Can be tailored for higher operating temperatures up to 600 oC.

Accuracy: 1% full scaleProof Pressure: 150% full scale Burst Pressure: 200% full scale Wheatstone Bridge Design Gage Factor: 35 to 100

Dynamic Frequency Response: >30 kHz Dimensions: < = 9 mm dia. Sensing element size: small as 0.5 x 0.5 mm

A 4th year mechatronic student is designing high pressure sensor for hypersonic application


Cricket-Inspired Sensory Hairs with Capacitive Motion Detection

Courtesy University of Twente, MESA+

Research Institute

12


• Perception of air flow and escape action of crickets

• Mechanical and functional properties of filiform hair• Design and realize large arrays of MEMS sensors


• Si capacitive sensor: made of single crystal silico n and glass• Design ensures exceptional reliability• Excellent accuracy and stability over time and temp erature.

Capacitive detection principle is simple and stable, based on the variation of a gap between two planar surfaces. The capacitance or charge storage capacity of a pair of plates depends on the gap width and plate area.

Accelerometer

13


Accelerometers in two basic types: comb and diaphragm.

With comb-type MEMS accelerometers , changes in g-forces cause the interleaved fingers of the comb to bend, resulting in a measurable change in conductivity, also called a piezoelectric effect.

Diaphragm type accelerometers have a thin silicon diaphragm over a charged plate. As the distance between the flexible silicon layer and the charged plate change, so does the capacitance.

Comb-type Accelerometer


The cantilever structure was formed out of silicon and was made suitably to comply with the mass or pressure variations due to change in humidity.

The design also incorporates integration of the platinum based temperature sensor and a platinum based heater.

The key point is to keep all the electrodes and leads at one convenient end for easy packaging and providing power to the sensor and to take leads for the outputs.

using a micro cantilever beam

K.Govardhan and Z.C.Alex, Proceedings of ISSS 2005

Humidity Sensor

14


Inexpensive and easy-to-use three-axis accelerometer devices will find applications in toys, industrial production equipment, robotics and automotive systems. It is also useful as a general-purpose vibration sensor for industrial equipment and domestic appliances.

Three-Axis Linear Accelerometer, in a compact package, the first one-chip three-axis MEMS accelerometer sensor, plus an interface chip that translates movement and inclination into calibrated analog voltage or digital outputs. Compared to multiple one-axis sensors the new device simplifies assembly, reduces size and cuts production costs.

Accelerometers based on silicon-micromachined MEMS technology are effective because they provide high sensitivity and precision together with the economies of scale of the wafer batch process used to make integrated circuits.

Other Applications


Omron will display its innovative portfolio of photomicrosensors(optoswitches) and intelligent sensors for detection of mass and velocity gas flow, and differential and gauge pressure changes

Among the highlights of the show will be Omron's ne w range of MEMS precision velocity and large mass airflow sensors and the new capacitive touch sensor

Omron's D6F-W MEMS-based sensors are to detect clogged air intake filters and air velocity flows in office automation equipment, domestic air purifiers and coolers, and other more conventional applicatio ns.

Health Products

15


Military Uses


High sensitivitywide bandwidth detection

Real time spectral detectionfast tunable filters

High spectral resolutionMEMS technology for Large 2D arrays

MEMS Infrared Detector forThermal Imaging

MEMS Sensor Development

16


Infrared Detector

( )2

2

=d

VAxFe

ε

substrate

V

MetalMembraneThin film mirror

substrate

V

substrate

V

Electrostatic tuning to change cavity length

substrate

V

substrate

V

substrate

V

substrate

V

substrate

V

Wavelength (Wavelength (Wavelength (Wavelength (µµµµmmmm))))

2 2.2 2.4 2.6 2.8 3 3.2

Tra

nsmission

Tra

nsmission

Tra

nsmission

Tra

nsmission

Detector

0.0%

25.0%

50.0%

75.0%

100.0%

d=900 nm d=1700 nm

Cavity Length, d

MirrorMirrorMirrorMirror

MirrorMirrorMirrorMirror

IncidentIncidentIncidentIncident

IRIRIRIR

ReflectedReflectedReflectedReflected

IRIRIRIR

Transmitted IRTransmitted IRTransmitted IRTransmitted IR

FabryFabry--Perot FilterPerot Filter


Ground

Top Mirror

SiNx Layer

Infrared Detector Models

17


After Wet Release (still in fluid – blue filter) - Before CPD

After CPD – blue filter

Testing Models


Making MEMS via Surface Micromachining

Deposition and patterning of sacrificial material

substrate

sacrificial

Deposition and patterning of material used for the suspended structuresubstrate

Removal of the sacrificial layermembrane

Class 1000 clean room

By PECVD

18



205nm

-185nm Blue Filter 220nm Fringe-to-Fringe

MEMS Infrared Sensor Array

19


References

• Experimental Methods for Engineers, J. P. Holman, 7th Edition, McGraw-Hill, 2001.

• MEMS Mechanical Sensors, Edited by S. Beeby et al, ARTECH House,Inc., 2004.

• http://airglow.csl.uiuc.edu/Teaching/ECE437/

• http://www.sensortechnics.com• http://www.wtec.org/loyola/mems/c3_s2.htm

• H. Huang, J. Micromech. Microeng. 15 (2005) 608–614.• K. Govardhan and Z.C. Alex, Proceedings of International Conference

on Smart Materials Structures and Systems, July 28-30, 2005, Bangalore, India, pp20-27.

L2 Sensor Introd

Documents

Transcript of L2 Sensor Introd