measurements & instrumentation
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TRANSCRIPT
HAI EVERYBODY…
Be the best in ever…
By …
Pavithra.S
SMART SENSORS
UNDER THE TOPIC OF TRANSDUCER
INTRODUCTION DEFINTION USEFULLNESS OF SILICON
TECHNOLOGY IN SMART SENSOR SIGNAL CONVERSION EFFECTS ENHANCEMENT OF APPLICATION SYSTEM RELIABILITY BETTER SIGNAL NOISE RATIO IMPROVEMENT IN
CHARACTERISTICS GENERAL ARCHITECTURE OF
SMART SENSOR
SUMMARY
WHAT IS MEANT BY TRANSDUCER?.... TRANSDUCER IS DEFINED AS A DEVICE THAT RECEIVES ENERGY FROM
ONE SYSTEM AND TRANSMITS TO ANOTHER. (WHICH CONVERTS PHYSICAL QUANTITY
INTO ELECTRICAL SIGNAL)IT’S ALSO CALLED AS ‘PICKUP’
TRANSDUCER
DEFINITION [Sensor means which detects/measures
the device Example: thermometer SMART SENSOR WITH INTEGRATED
ELECTRONICS THAT CAN PERFORM ONE OR MORE OF THE FOLLOWING FUNCTION….
LOGIC FUNCTIONS TWO WAY COMMUNICATION MAKE DECISIONS…..
Usefulness of silicon technology in smart sensor
convincing advantages of using silicon technology as integrated circuits. Sensor is made with a same technology as integrated circuits. it utilizes the properties of silicon (GaAs).
a transduction element either includes thin metal films,zinc oxide & polymeric films
integrated sensors provide significant advantages in terms of overall sizes & the ability to use small signals from the transduction element.
IC (integrated circuit) industry will get involved in smart sensor if a very large market can be captured &the production of smart sensor doesn’t require non-standard processing steps…..
Signal domain examples
Radiant Light intensity,polarization,phase, wavelength
mechanical Force,pressure,flow,vaccum, thickness
thermal Temperature,temp gradient,thickness
chemical Concentration,toxicity,pH
magnetic Field intensity,flux density,permeability
Signal conversion effects
Signal domain examples
Radiant Photo voltaic effect,photo electric effect,photo magneto-electric effect,photo conductivity
mechanical Piezo resistivity
thermal Seebeck effect,temperatre dependence of conductivity
chemical Ion sensitive field effect
magnetic Hall effect,magneto resistance
Radian signal domain:Radiant silicon can be used to connect a sensor for sensing wide range of radiant signal from gamma rays to infrared. Silicon can be used for the fabrication of photoconductors,phototransistor or to detect nuclear radition.
silicon can be used for measuring force and pressure because of the piezo resistance effect.
This effect is large because the average mobility of electrons and holes in siliconis strongly affected by the application of strain
silicon can alo be used for the measurement of air or gas velocities.
Mechanical signal domain
Smart sensor also enhances the following applications:
self calibration- adjusting some parameter of sensor during fabrication.
-calibration is needed bcoz, their adjustments usually change with the time that needs the device to be removed & recalibrated.thee problems are solved by
smart sensor(has the the correction functions in memory).
Enhancement of application
computation- it also allows one to obtain the average, varience & standard deviation for set of measurement.this can be easily done done using smart sensor
- to compensate for the environmental change such as temperature.
communication- communication means of exchanging or conveying information.
multisensing – a single smart sensor can measure pressure ,temperature,humidity, gas flow &infra red….
System reliability System reliability is significantly improved due to the utilization of smart sensors
Non linearity Cross sensitive(shows an un desairable
sensitivity to strain &temperature ) Offset(well reduced by sensitivity reduction
method) Parameter drift & componeent values(these
are functions of time it can be solved by automatic calibration)
Improvement in characteristics
Thermal signal domain- measurement of temperature by using two bipolar transistors with a cons.ratio of emitter current.
Magnetic signal domain-silicon is a non magnetic material. But it can be used for the construction of hallplates &transistor structure that are sensitive to magnetic fields.
Chemical signal domain-ISFET is suitable for such application.
Signal domains
The presence in smart sensor has led to corrections for different un desirable sensor characteristics which include,
input offset &span variation, non linearity & cross sensitivity .as these are carried in software no additional software is required
thus calibration becomes an electronic process
Importance &adoption of smart sensor
Sensor inside hardware is more complex in the sensor on the other hand it is outside the sensor.
Reduced cost of bulk cables & connectors
To reduce the cost of bulk cables & connectors needed to connect different blocks
Cost improvement
Block diagram
General architecture of smart sensor
Transducer 1
Transducer 1
Transducer 1
Transducer 1
A1
A1
A1
A1
S/H1
S/H2
S/H3
S/H4
ANALOG MUX
ADC
Offset correction& temp drift
compensation
sample&Hold control
processor Serial communication
memory DAC