8. 0 Sensor and sensing Technology

1.0 Objective

At the end of the lesson, student will be able to describe:

• Recognize sensor terminologies

• Types of sensor and sensor technology design consideration

• Function and application of sensor

Introduction A device which senses and detects the physical quantity of measurand and

converts to electrical form.• Example of sensors:• Mechanical : Bourdon tube pressure meter.• Electrical : Potentiometer• Optical : Photon counter• Chemical : Thermocouples

*All sensors are transducers but not all transducers are sensorsIn this lecture we also discuss

I. Sensors and the Environment

II. Sensor Development

III. Current Sensors – Terrestrial / Aquatic

IV. The next phase of In-Situ Sensors

V. Current Opportunities / Future Outlook

Sensor Technology - TerminologySensor Technology - Terminology

• Transducer is a device which transforms energy from one type to another, even if both energy types are in the same domain.– Typical energy domains are mechanical, electrical,

chemical, magnetic, optical and thermal.

• Transducer can be further divided into Sensors, which monitors a system and Actuators, which impose an action on the system.– Sensors are devices which monitor a parameter of a

system, hopefully without disturbing that parameter.

Sensor in control system

• In a simplified definition - an input of the required value of some variable and an output of the variable at the desired value.

CONTROL SYSTEM

INPUT

The required value of a variable

OUTPUT

The variable at the desired value

The Basic ElementsControl systems consist of the following essential elements, or components. • A measuring device which reacts to the machinery or process parameter to

be controlled, such as temperatures, pressure or rotational speed. • In its simplest form, where only a single measurement value is required, this

could be a temperature, pressure or centrifugal switch. For measurement throughout a whole range of values a transducer would be employed having all or some of the following components: – A sensing element which possesses some property which varied with changes in

the parameter to be measured. For instance, increasing temperature causes mechanical bending of a bi-metallic strip, increase in the electrical resistance of a coil of platinum wire and increase or decrease in the electrical resistance of a thermistor, depending on its type.

– A conversion device to produce an output signal in a form that the control system can use. There are standardised ranges of output signal so, in the above examples, a pneumatic signal in the pressure range 0.2 – 1.0 bar could be produced by the movement of the bi-metallic strip against a nozzle, or the resistance values could be converted to 4 – 20 mA current signals, or voltages in the 0 – 10 V resistance or thermocouple devices.

The Basic Elements• Conversion devices usually involve some degree of amplification of the

signal from the sensor and produce output signals which can be transmitted for some distance without loss of accuracy. For long distance transmission the signal must be converted to a form which does not loose accuracy even though the signal strength is diminished. This could be a frequency modulated (FM) voltage signal or a serial digital transmission.

– Compensation arrangements to protect the output signal from variation due to changes in parameters other than the one being measured. For instance, pressure transducers which employ strain gauges on diaphragms or tubes are provided with dummy gauges to compensate for changes in ambient temperature.

• A controller, which evaluates the deviation, i.e. the difference between the measured value and the desired value of the controlled condition (the set point value) and determines the output control signal, i.e. the setting of the actuator at any given time. Types and actions of controllers are discussed later.

• An actuator or other similar final controlling element, which performs the necessary correcting action, such as an electric motor to open or close a valve.

SensorsSensors

Definition: a device for sensing a physical variable of a physical system or an environment

Classification of Sensors• Mechanical quantities: displacement, Strain, rotation velocity, acceleration, pressure, force/torque, twisting, weight, flow• Thermal quantities: temperature, heat.• Electromagnetic/optical quantities: voltage, current, frequency phase; visual/images, light; magnetism.• Chemical quantities: moisture, pH value

Sensors

• USE: To understand and interpret the environment.• IN-SITU (vs. Remote): a) detectors at sight

b) higher resolution c) means to ground

truth

• DETECTION:a) physical – heat, pressure, humidity, light, sound

b) chemical – gas, liquid, solid, organics / inorganics

c) biological – gas signature, DNA, protein, acoustics

Categorization of SensorCategorization of Sensor

• Classification based on physical phenomena– Mechanical: strain gage, displacement (LVDT), velocity (laser

vibrometer), accelerometer, tilt meter, viscometer, pressure, etc.– Thermal: thermal couple– Optical: camera, infrared sensor– Others …

• Classification based on measuring mechanism– Resistance sensing, capacitance sensing, inductance sensing,

piezoelectricity, etc.

• Materials capable of converting of one form of energy to another are at the heart of many sensors. – Invention of new materials, e.g., “smart” materials, would permit

the design of new types of sensors.

Paradigm of Sensing System DesignParadigm of Sensing System Design

Zhang & Aktan, 2005

Instrumentation ConsiderationsInstrumentation Considerations

• Sensor technology;

• Sensor data collection topologies;

• Data communication;

• Power supply;

• Data synchronization;

• Environmental parameters and influence;

• Remote data analysis.

MeasurementMeasurement

Physical phenomenon

Measurement Output

Measurement output:• interaction between a sensor and the environment surrounding the sensor• compound response of multiple inputs

Measurement errors:• System errors: imperfect design of the measurement setup and the approximation, can be corrected by calibration• Random errors: variations due to uncontrolled variables. Can be reduced by averaging.

Specifications of SensorSpecifications of Sensor

• Accuracy: error between the result of a measurement and the true value being measured.

• Resolution: the smallest increment of measure that a device can make.

• Sensitivity: the ratio between the change in the output signal to a small change in input physical signal. Slope of the input-output fit line.

• Repeatability/Precision: the ability of the sensor to output the same value for the same input over a number of trials

Accuracy vs. PrecisionAccuracy vs. Precision

Precision without accuracy

Accuracy without precision

Precision and accuracy

Specifications of SensorSpecifications of Sensor

• Dynamic Range: the ratio of maximum recordable input amplitude to minimum input amplitude, i.e. D.R. = 20 log (Max. Input Ampl./Min. Input Ampl.) dB

• Linearity: the deviation of the output from a best-fit straight line for a given range of the sensor

• Transfer Function (Frequency Response): The relationship between physical input signal and electrical output signal, which may constitute a complete description of the sensor characteristics.

• Bandwidth: the frequency range between the lower and upper cutoff frequencies, within which the sensor transfer function is constant gain or linear.

• Noise: random fluctuation in the value of input that causes random fluctuation in the output value

Attributes of SensorsAttributes of Sensors• Operating Principle: Embedded technologies that make

sensors function, such as electro-optics, electromagnetic, piezoelectricity, active and passive ultraviolet.

• Dimension of Variables: The number of dimensions of physical variables.

• Size: The physical volume of sensors.• Data Format: The measuring feature of data in time;

continuous or discrete/analog or digital.• Intelligence: Capabilities of on-board data processing and

decision-making.• Active versus Passive Sensors: Capability of generating

vs. just receiving signals.• Physical Contact: The way sensors observe the

disturbance in environment.• Environmental durability: is the sensor robust enough

for its operation conditions

Consideration for Strain Gauges sensor Consideration for Strain Gauges sensor technolologytechnolology

• Foil strain gauge– Least expensive– Widely used– Not suitable for long distance– Electromagnetic Interference– Sensitive to moisture & humidity

• Vibration wire strain gauge– Determine strain from freq. of AC signal– Bulky

• Fiber optic gauge– Immune to EM and electrostatic noise– Compact size– High cost– Fragile

Strain SensingStrain Sensing

• Resistive Foil Strain Gage– Technology well developed; Low cost – High response speed & broad frequency

bandwidth– A wide assortment of foil strain gages

commercially available– Subject to electromagnetic (EM) noise,

interference, offset drift in signal. – Long-term performance of adhesives used for

bonding strain gages is questionable• Vibrating wire strain gages can NOT be

used for dynamic application because of their low response speed.

• Optical fiber strain sensor

Strain SensingStrain Sensing• Piezoelectric Strain Sensor

– Piezoelectric are ceramic-based or Piezoelectric polymer-based (e.g., PVDF)

– Very high resolution (able to measure nanostrain)– Excellent performance in ultrasonic frequency range, very high

frequency bandwidth; therefore very popular in ultrasonic applications, such as measuring signals due to surface wave propagation

– When used for measuring plane strain, can not distinguish the strain in X, Y direction

– Piezoelectric ceramic is a brittle material (can not measure large deformation)

Courtesy of PCB Piezotronics

Acceleration SensingAcceleration Sensing

• Piezoelectric accelerometer– Nonzero lower cutoff frequency (0.1 – 1 Hz for 5%)– Light, compact size (miniature accelerometer weighing

0.7 g is available)– Measurement range up to +/- 500 g– Less expensive than capacitive accelerometer– Sensitivity typically from 5 – 100 mv/g– Broad frequency bandwidth (typically 0.2 – 5 kHz)– Operating temperature: -70 – 150 C

Photo courtesy of PCB Piezotronics

Acceleration SensingAcceleration Sensing

• Capacitive accelerometer– Good performance over low frequency range, can measure

gravity!– Heavier (~ 100 g) and bigger size than piezoelectric

accelerometer– Measurement range up to +/- 200 g– More expensive than piezoelectric accelerometer– Sensitivity typically from 10 – 1000 mV/g– Frequency bandwidth typically from 0 to 800 Hz– Operating temperature: -65 – 120 C

Photo courtesy of PCB Piezotronics

AccelerometerAccelerometer

Force SensingForce Sensing

• Metal foil strain-gage based (load cell)– Good in low frequency response– High load rating– Resolution lower than piezoelectricity-based– Rugged, typically big size, heavy weight

Courtesy of Davidson Measurement

Force SensingForce Sensing

• Piezoelectricity based (force sensor)– lower cutoff frequency at 0.01 Hz

• can NOT be used for static load measurement

– Good in high frequency– High resolution– Limited operating temperature (can not be used for high

temperature applications)– Compact size, light

Courtesy of PCB Piezotronics

Displacement SensingDisplacement Sensing

• LVDT (Linear Variable Differential Transformer):– Inductance-based electromechanical

sensor– “Infinite” resolution

• limited by external electronics– Limited frequency bandwidth (250 Hz

typical for DC-LVDT, 500 Hz for AC-LVDT)– No contact between the moving core and

coil structure • no friction, no wear, very long operating

lifetime– Accuracy limited mostly by linearity

• 0.1%-1% typical– Models with strokes from mm’s to 1 m

available

Photo courtesy of MSI

Displacement SensingDisplacement Sensing

• Linear Potentiometer

– Resolution (infinite), depends on?– High frequency bandwidth (> 10 kHz)– Fast response speed– Velocity (up to 2.5 m/s)– Low cost– Finite operating life (2 million cycles) due to contact

wear– Accuracy: +/- 0.01 % - 3 % FSO– Operating temperature: -55 ~ 125 C

Photo courtesy of Duncan Electronics

Displacement TransducerDisplacement Transducer

• Magnetostrictive Linear Displacement Transducer– Exceptional performance for long stroke position measurement

up to 3 m– Operation is based on accurately measuring the distance from a

predetermined point to a magnetic field produced by a movable permanent magnet.

– Repeatability up to 0.002% of the measurement range. – Resolution up to 0.002% of full scale range (FSR)– Relatively low frequency bandwidth (-3dB at 100 Hz)– Very expensive– Operating temperature: 0 – 70 C

Photo courtesy of Schaevitz

Displacement SensingDisplacement Sensing

• Differential Variable Reluctance Transducers – Relatively short stroke– High resolution– Non-contact between the measured object and sensor

Type of Construction Standard

tubular

Fixing Modeby 8mm

diameter

Total Measuring Range

2(+/-1)mm

Pneumatic Retraction No

Repeatability 0.1um

Operating Temperature Limits

-10 to +65 degrees C

Courtesy of Microstrain, Inc.

Velocity SensingVelocity Sensing

• Scanning Laser Vibrometry – No physical contact with the test object; facilitate remote,

mass-loading-free vibration measurements on targets – measuring velocity (translational or angular)– automated scanning measurements with fast scanning speed – However, very expensive

Photo courtesy of Bruel & Kjaer

Photo courtesy of Polytec

Shock (high-G) SensingShock (high-G) Sensing

• Shock Pressure Sensor– Measurement range up to 69 MPa (10 ksi)– High response speed (rise time < 2 sec.)– High frequency bandwidth (resonant

frequency up to > 500 kHz) – Operating temperature: -70 to 130 C– Light (typically weighs ~ 10 g)

• Shock Accelerometer– Measurement range up to +/- 70,000 g– Frequency bandwidth typically from 0.5 –

30 kHz at -3 dB– Operating temperature: -40 to 80 C– Light (weighs ~ 5 g)

Photo courtesy of PCB Piezotronics

Angular Motion Sensing (Tilt Meter)Angular Motion Sensing (Tilt Meter)

• Inertial Gyroscope (e.g., http://www.xbow.com)– used to measure angular rates and X, Y, and Z acceleration.

• Tilt Sensor/Inclinometer (e.g., http://www.microstrain.com)– Tilt sensors and inclinometers generate an artificial horizon and

measure angular tilt with respect to this horizon.

• Rotary Position Sensor (e.g., http://www.msiusa.com)– includes potentiometers and a variety of magnetic and capacitive

technologies. Sensors are designed for angular displacement less than one turn or for multi-turn displacement.

Photo courtesy of MSI and Crossbow

http://www.gmu.edu/departments/seor/student_project/syst101_00b/team07/components.html

Micro-Electric Mechanical Systems (MEMS)

– receives data, processes it, decides what to do based on data

-gathers biological, chemical, physical environmental data

(brains)

(eyes, nose, ears . . .)

- act as a switch or trigger, activate external device.

- valves, pumps, micro-fluidics

MEMS TechnologyMEMS Technology

• What is MEMS?– Acronym for Microelectromechanical Systems– “MEMS is the name given to the practice of making and

combining miniaturized mechanical and electrical components.”– K. Gabriel, SciAm, Sept 1995.

• Synonym to:– Micromachines (in Japan)– Microsystems technology (in Europe)

• Leverage on existing IC-based fabrication techniques (but now extend to other non IC techniques)– Potential for low cost through batch fabrication– Thousands of MEMS devices (scale from ~ 0.2 m to 1 mm)

could be made simultaneously on a single silicon wafer

MEMS TechnologyMEMS Technology

• Co-location of sensing, computing, actuating, control, communication & power on a small chip-size device

• High spatial functionality and fast response speed– Very high precision in manufacture– miniaturized components improve

response speed and reduce power consumption

MEMS Fabrication Technique

Courtesy of A.P. Pisano, DARPA

Distinctive Features of MEMS DevicesDistinctive Features of MEMS Devices

• Miniaturization– micromachines (sensors and actuators) can handle

microobjects and move freely in small spaces

• Multiplicity– cooperative work from many small micromachines

may be best way to perform a large task– inexpensive to make many machines in parallel

• Microelectronics– integrate microelectronic control devices with sensors

and actuators Fujita, Proc. IEEE, Vol. 86, No 8

MEMS AccelerometerMEMS Accelerometer

• Capacitive MEMS accelerometer– High precision dual axis

accelerometer with signal conditioned voltage outputs, all on a single monolithic IC

– Sensitivity from 20 to 1000 mV/g

– High accuracy– High temperature stability – Low power (less than 700 uA

typical) – 5 mm x 5 mm x 2 mm LCC

package – Low cost ($5 ~ $14/pc.)

Courtesy of Analog Devices, Inc.

MEMS Accelerometer

• Piezoresistive MEMS accelerometer– Operating Principle: a proof mass attached to a silicon

housing through a short flexural element. The implantation of a piezoresistive material on the upper surface of the flexural element. The strain experienced by a piezoresistive material causes a position change of its internal atoms, resulting in the change of its electrical resistance

– low-noise property at high frequencies

Courtesy of JP Lynch, U Mich.

MEMS Dust • MEMS dust here has the same scale as a

single seed - something so small and light that it literally floats in the air.

Source: Distributed MEMS: New Challenges for Computation, by A.A. BERLIN and K.J. GABRIEL, IEEE Comp. Sci. Eng., 1997

Major Ecological Focal Points• GLOBAL CHANGE

– Nature and pace of climate change? * Requires – A global heat and water balance (ocean, land, atm)

– Nature and pace of biological change? * Requires – census of life & functional role of biodiversity

Who’s there? How many? What are they doing?

• BIOCOMPLEXITY– Understanding patterns & processes across

a) levels of organization: molecular global b) across space and time: arctic tropical

Physical Biological Chemical

Terrestrial

                                                                                                  

http://www.dynamax.com/

• FUNCTION: Measures Sap Velocity g/hr (transpiration)

• APPLICATION: herbs, grasses, shrubs, trees

• PRINCIPLE: thermocouples (heat), plant energy balance

• PROS: Real-Time, No calibration, non-intrusive

• CONS: need many, not wireless

• COMPANY: Dynamax, Advanced Measurements and Controls Inc, Delta-T

• COST: $200 - $3500+

Sap Flow Sensors

- http://www.lotek.com/

• FUNCTION: Organism tracking & Sensing

• APPLICATION: Birds, Bats, Fish, Reptiles, Mammals

• PRINCIPLE: Micro-sensors (position, pressure, temp), Radio & Acoustic waves

• PROS: Wireless, Small, Long use history, No calibration, Real-time option

• CONS: Intrusive, Power limitations

• COMPANY: Lotek, Telonics Inc, Holohil Systems Ltd

• COST: $135 - $350+

Radio & Acoustic Telemetry

http://www.holohil.com/lb2pic.htm

http://www.bartztechnology.com/products.htm

• FUNCTION: Soil observatory

• APPLICATION: Soils, Root studies, Soil fauna

• PRINCIPLE: Video, Magnification

• PROS: Non-destructive, Small, 100xmagnification, soon Automated

• CONS: Manual, Physical data only

• COMPANY: Bartz Technology

• COST: $13,000 - $16,500+

Minirhizotron

• FUNCTION: 3-D ground mapping

• APPLICATION: Soils, Roots, Groundwater, Rocks,

Nests, Forests, Lakes, Deserts, Ice . . .

• PRINCIPLE: EM wave propagation

• PROS: Non-invasive, Rapid, Hi-resolution, Long use history

• CONS: Depth limitation,

• COMPANY: Sensors & Software Inc., GeoModel, Inc.

• COST: varies

http://www.uwec.edu/jolhm/research/Brian/what_is_ground_penetrating_radar.htm

Ground Penetrating Radar (GPR)

Physical Biological Chemical

Aquatic Environments

http://www.hydrolab.com/

• FUNCTION: Measures 15 or more parameters including: Temperature, pH, Nutrients, Gas, Chlorophyll

• APPLICATION: Fresh & Marine water (physical, chemical)

• PRINCIPLE: Sensor cluster & Datalogger

• PROS: Multiple parameters simultaneously, Automated

• CONS:

• COMPANY: Hydrolab, In-Situ Inc, Advanced Measurements and Controls Inc.

• COST: $3000 - $4000+

Multi-Parameter Sondes

http://www.rdinstruments.com/ • FUNCTION: Currant and Wave velocity profiler

• APPLICATION: Oceans, Rivers, Discharge

• PRINCIPLE: Doppler shift

• PROS: Real-time, Quick & Accurate

• CONS:

• CONTACTS: RD Instruments, Nortek, Sontek

• COST: $15,000 - $23,000

Acoustic Doppler Current Profiler

Wireless Moored ProfilerWireless Moored Profiler

http://www.dsl.whoi.edu/DSL/dana/abe_cutesy.html

• FUNCTION: Automated ocean surveyors

• APPLICATION: Deep ocean surveys

• PRINCIPLE:Video, Temp, Salinity, Magnetometer, Optical backscatter, Acoustic altimeter

• PROS: ‘Smart’, Autonomous, Multiple parameters

• CONS: Prototype

• COMPANY: Dana R. Yoerger - WHOI

Autonomous Underwater Vehicles (AUV)

Autonomous Benthic Explorer (ABE)

http://science.whoi.edu/users/sgallager/vprwebsite/vprdraft.html

• FUNCTION: Autonomous plankton observatory

• APPLICATION: Oceans, Estuaries, Lakes

• PRINCIPLE: Video, Sensors

• PROS: Plankton imaged & environmental data measured, ‘real time’, autonomous

• CONS: Prototype

• COMPANY: Scott Gallager - WHOI

Video Plankton Recorder

http://www.nsf.gov/od/lpa/news/press/01/pr0130_progress.htm

• FUNCTION: Aquatic biological assessment & physical parameters

• APPLICATION: Oceans, Coasts

• PRINCIPLE: Acoustic & Optical sensors, CTD Fluorescence, Salinity

• PROS: Robust biological assessment & Environmental data

• CONS: Prototype

• COMPANY: Peter Wiebe - WHOI

BIOMAPER II (BIo- Optical Multifrequency Acoustical and

Physical Environmental Recorder )

• FUNCTION: Acoustical, Physiological, and Environmental data (6-9 hrs)

• APPLICATION: Marine mammals (whales, dolphins, manatees etc)

• PRINCIPLE: Micro-sensors (pressure, hydrophone, temp, accelerometer) VHF radio beacon

• PROS: Non-invasive, Compact, Re-useable, Over 2000m depth, Tag potted in epoxy,

• CONS: Suitability depends upon Movement and Skin quality, Challenging to apply• COMPANY: Mark Johnson – WHOI

• COST: $10,000 – $15,000

http://dtag.whoi.edu/tag.html

Digital Whale Tag

Photos: Copyright, Woods Hole Oceanographic Institution, The DTAG Project. Mark Johnson and Peter Tyack, funded by ONR, NMFS, WHOI.

• FUNCTION: Pressure, Temperature, Micro-hygrometer, Radiation Densitometer, Laser Doppler anemometer

• APPLICATION: in-situ microclimate data

• PRINCIPLE: Micro-sensor clusters

• PROS: Accuracy, Fast response, Low mass & Volume, Cheap

• CONS: not yet available

• COMPANY: JPL, GWU

• COST: will be relatively cheap

Mini-weather stations

Micro-hygrometer

JPL - http://www.jpl.nasa.gov/technology/

BATTERIES DRAIN

LED PD

MICRO-SENSORCLUSTER

(Temp, Pressure & Humidity)

ANTENNAINSIDE

BATTERYCOMPARTMENT

RAIN GAGE

WIND GAGE

CYLINDRICALPLASTICHOUSING

MICROCONTROLLER

FIVE CENTIMETERDIAMETERM

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$50

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COMPANY - GWU

•Alkanes

•Cyclo-Alkanes

•Alkenes

•Alcohols

•Aromatics

•Ketones

•Esters

•Organo Phosphonates

•Pesticides

•Amines

•Pyridines

•Phenols

•Organic Acids

•Aldehydes

•Halides

- http://www.femtoscan.com/evm.htm

• FUNCTION: Vapor detector

• APPLICATION: Trace gases emissions

• PRINCIPLE: Ion mobility spectrometry, Gas chromatography

• PROS: Real-time, No carrier gas, ppb sensitivity, Hand portable, Reliable, Good reproducibility

• CONS: Expensive

• COMPANY: Femtoscan, HAPSITE

• COST:

Portable Gas Chromatograph

http://www.sandia.gov/media/NewsRel/NR2000/labchip.htm

• FUNCTION: Autonomous chemical detector

• APPLICATION: Gas, Liquid, DNA

• PRINCIPLE: GC/LC separator & coated SAW array

• PROS: Ppb level detection, Gas & Liquid, Small

• CONS: not yet available

• COMPANY: Sandia, Eksigent Technologies

• COST: ~$5000

Chem-lab on a chip

• FUNCTION: ID gases and quantify concentrations (ppb- ppt)

• APPLICATION: Air, Water, Soil, Plant volatiles. . .

• PRINCIPLE: SAW sensor(s) & Micro-GC

• PROS: Quick (10 sec), Small, Sensitivity, Remote option

• CONS:

• COMPANY: Estcal, JPL

• COST: $19, 450 - $24, 950+

http://www.estcal.com/Products.html

Electronic Nose (s)zNose ©

http://www.businessplans.org/Vusion/Vusion00.html

• FUNCTION: ID chemical composition of liquids

• APPLICATION: Dissolved organics & inorganics, Aquatic mold growth, Soil analysis

• PRINCIPLE: 100’s of microsensors on chip, Colors change depending on chemicals, Results read by camera on a chip

• PROS: Cheap, Disposable, Qualitative, Quantitative, Several analyses simultaneously

• CONS: not commercially available in US

• COMPANY: ALPHA M.O.S, Vusion, Inc. UT Austin, JPL

• COST: Inexpensive

http://www.alpha-mos.com/proframe.htm

Electronic Tongue

• FUNCTION: Wireless microsensor clusters for Spacial and Temperal monitoring

• APPLICATION: Terrestrial, Atmosphere, Gases

• PRINCIPLE: Microsensor clusters, RF telemetry

• PROS: Small, Wireless, Low power, Custom sensor design, Affordable, Available, Information shared between pods

• CONS:

• COMPANY: Kevin Delin – JPL

• COST: $750 / pod

Sensor Webs

Nano-Technology

• Nano-scale size

• Constructed atom / molecule at a time

• Self-repairing

• Self-assembling – ex. carbon nanotubes

• Molecular switches (transistor) - UCLA

• Model – nature

• Still in development phase

Home Interior Flowchart

MCUTI MSP430F149

Touch Sensors

RS-485 Transceiver

1 Mb Flash

LCD Display

USB Endpoint

8-bit Parallel Bus SPI Bus

DigitalPotentiometer

MCUTI MSP430F169

RS-485 Transceiver

USB

USB Endpoint

US

B

Optional USB alternative to RS-485 / Base Station

RS

-48

5 B

usQuadrature

Encoders

PW

M

Level 1/ Base Station Block Diagram

Areas of Opportunity• Technological overlaps with NASA, DoE, DoD

• Opportunity to custom design arrays of sensor clusters – Sensors can be chosen specific to the research

question

• View interactions between levels of organization

• Technological outlook– Micro-technology: Present - 5+ years – Nano-technology: 5 - 10+ years:

Future Directions

• Power

• Automated data assimilation & analysis

• Decreased costs– Maintenance-free– Long-term

• Increased miniaturization

Smart Sensor Web

Sap Flow Sensor Array

MinirhizotronArray

Multiparameter Soil Probes

‘Smart Dust’ tagged Insects Automated E-tongue

Sensor Clustered MEMS Insects

RF Telemetry Macro-organisms

Instrumenting the Environment

Micro-weather Stations

E-nose

Sensor Industry

• ADVANCES: smaller, faster, cheaper, decreased power demand, ‘smart’, wireless . . .

• INDUSTRY:

a) Over 100 properties can be sensed

b) Over 2300 sensor suppliers . . .

Major Areas of Sensor Development

• Governmental – DoD– DoE– NASA– NOAA– Health

• Private Sector– Communications– Electronics– Industrial

Focus - miniaturization - automation - bio / chem detection - environmental sensing - decreased power - faster - ‘smarter’ - wireless - remote / in-situ

Examples of Micro-Sensor Cluster Groups

• UC Berkeley – COTS – ‘Smart Dust’

• Michigan - WIMS (Wireless Integrated Micro Systems)

• GWU - ‘Mini Weather Stations’

• NASA - JPL – Sensor Webs

• DoE – Sandia, Oak Ridge

• DoD – Naval Research Lab

References

Zhang, R. and Aktan, E., “Design consideration for sensing systems to ensure data quality”, Sensing issues in Civil Structural Health Monitoring, Eded by Ansari, F., Springer, 2005, P281-290

Structural health monitoring using scanning laser vibrometry,” by L. Mallet, Smart Materials & Structures, vol. 13, 2004, pg. 261