Submitted by Nadim Equbal
Roll No : 09EE010
Regd. No : 0901223054
Under the guidance of Prof Sangita Das,
Dept. of Electrical Engineering
CONTENTS
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Abstract
Introduction
Properties
Developments of sensor technology
Sensor design
Sensor structure
Types of sensors
Advanced sensor technology
Conclusion
References
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ABSTRACT ON SENSOR TECHNOLOGY
The sensor technology plays a key role in the design of advanced electronic equipments
and many other emerging fields. Without sensors most electronic applications would not
exist. They perform a vital function, namely providing an interface to the real
world. They determine the quality of the information that is acquired from real life and
are used for production control and decision making. The global market for sensors is
fast growing and the innovation rate is extremely high. The importance of sensors,
however, contrasts with the limited information available on them. Today's smart
sensors, wireless sensors, and micro technologies are revolutionizing sensor design and
applications. This paper includes basic information about sensor, its types and its
applications in advanced technology.
A sensor (also called detectors) is a device that measures a measurable attribute and
converts it into a signal which can be read by an observer or by an instrument.
The need for new types of sensors is more critical than ever. This is due to the emergence
of increasingly complex technologies, health and security concerns of increasing world .
Properties
Developments of sensor technology
Sensor design
Sensor structure
Types of sensors
Advanced sensor technology
Conclusion
References .
INTRODUCTION
 A sensor (also called detectors) is a device that measures a
measurable attribute and converts it into a signal which can be read by
an observer or by an instrument.
 The need for new types of sensors is more critical than ever. This is due
to the emergence of increasingly complex technologies, health and
security concerns of increasing world population, and the emergence
of terrorist activities, among other factors. Sensors are the most
important component in any system and engineers in any field need to
understand the fundamentals of how these components work, how to
select them properly and how to integrate them into an overall system
Depending on their application, the design, fabrication, testing, and
use of sensors, all require various kinds of both technical and
nontechnical expertise. With this in mind, “Introduction to Sensors”
examines the theoretical foundations and practical applications
of various types of sensors.
PROPERTIES REQUIRED FOR A GOOD
SENSOR
 Accuracy - The statistical variance about the exact reading.
 Calibration - Required for most measuring systems since
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their readings will drift over time.
Environmental - Sensors typically have temperature
and/or humidity limits.
Range - Limits of measurement of the sensor.
Repeatability - The variance in a sensor's reading when a
single condition is repeatedly measured.
Resolution - The smallest increment the sensor can
detect.
TYPES OF SENSORS:
 Thermal Sensors:
 This device collects information for the temperature measurement. The
position of the mercury is observed by the viewer to measure the temperature.
 There are two basic types of temperature sensors:
 Contact Sensors:
 This type of sensor requires direct physical contact with the object or media
that is being sensed. They supervise the temperature of solids, liquids and
gases over a wide range of temperatures.
 Non contact Sensors:
 This type of sensor does not require any physical contact with the object or
media that is being sensed. They supervise non-reflective solids and liquids but
are not useful for gases due to natural transparency. These sensors use Plank’s
Law to measure temperaturen about temperature from a source and converts
into a form that is understandable by other device or person. The best
illustration of a temperature sensor is mercury in glass thermometer. The
mercury in the glass expands and contracts depending on the alterations in
temperature. The outside temperature is the source .
ADVANTAGES:
•
Has no effect on the medium it measures.
 Is precisely accurate.
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Responds instantly.
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Has an easily conditioned output.
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Accuracy.
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No Self-heat.
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Self-Powered.
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Overall Cost is low.
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Ease of Use.
DISADVANTAGES:
 Non-linearity.
 Moisture failures.
 Limited applications.
RESISTENCE TEMPERATURE
DETECTOR
 A resistance tempreture detector is a tempretutre
sensor based on the principle i.e metal resistance
increases with tempreture.
 Metals used in the devivce are nickle,platinum etc.
which is very sensitive.
 It has a time response of 0.5 to 5 sec generally.
 Poor thermal contact has slow response ,whereas good
thermal contact has fast response.
PHOTO
CONSTRUCTION
 An RTD is simply a length of wire whose resistance is
to be monitor as a function of tempreture.
 The wire is wound to form coil.
 The coil is protected from enviornment by protective
shreath.
LVDT
 LVDT(linear variable differential transformer).
 It is an important for displacement measurement in industrial
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environment.
It consist of three coils of wires wound on hollow form.
The inner coil is primary which is excited by some ac source.
A core of permeable material can slide freely through the centre.
Flux form by primary is linked by two secondary coil.
LVDT DIAGRAM
GRAPH
WORKING
When the core is centrally located the voltage in
eachcoil is equal.
If the core moves to one side or the other a larger ac
voltage will be induced.
This is due to change in flux associated with the core.
Hence by change in voltage motion of core is measured.
MERITS OF LVDT
 Linearty is good.
 Sensitivty is high.
 Low power and hysterisis loss
 Low cost
DEMERITS OF LVDT
 Ac input generates noise.
 Sensitivity is low at high temp.
 Affected by electromagnetic field.
BASICS OF SMART SENSOR
Complete sensor systems
have been realized on a
single chip where traditional
functions,such as signal
conditioning, datacommunication, A/D
conversion and the
generation of reference and
compensating signals are no
longer performed by separate
components, but are all
integrated on the same IC.
EVOLUTION OF SMART SENSORS
Sensors have progressed through following stages
 First generation devices
 Second generation devices
 Third generation devices
 Fourth generation devices
 Fifth generation devices
In fifth generation, data conversion is
accomplished on the same sensor chip
TECHNOLOGY OF SMART SENSORS
A modern microprocessor-cum-micro sensor is
composed of
(i) the sensing element
(ii) a signal processing part
(iii) the microprocessor
Parts (i) and (ii) are fabricated on a single chip to
form a smart sensor
SOME EXAMPLES OF SMART SENSORS
Different smart sensors are given below:
1.HALL SENSORS
2. THREE-DIMENSIONAL EYE MOVEMENT
MEASUREMENT USING SMART VISION SENSORS
3. SMART ACCELEROMETER SYSTEM
4. SMART AUDIO SENSOR FOR TELEMEDICINE
SMART VISION SENSORS
State-of-the-art
imaging technology
permits accurate threedimensional
measurement of eye
movement (horizontal,
vertical, torsional).
3D eye measurement is
done using this sensor
SMART VISION SENSOR AND HOST INTERFACE
IMPLEMENTATION AND FUTURE USE
There are many applications of smart sensors of
which some practical uses are realized as
1.Electronic compass for measurement of directions
with greater accuracy.
2. Hydraulic cylinder height application for
measurement of height
IR SENSOR
 This device emits and/or detects infrared radiation to sense a particular
phase in the environment. Generally, thermal radiation is emitted by
all the objects in the infrared spectrum. The infrared sensor detects
this type of radiation which is not visible to human eye. According to
the black body radiation law, it is possible to view the environment
with or without visible illumination using thermography. It is disturbed
by noises in the surrounding such as radiations, ambient light etc.
Fig. IR Sensor
 2.2) ADVANTAGES
 Easy for interfacing.
 Readily available in market.
UV Sensor:
 These sensors measure the intensity or power of the incident ultraviolet
radiation. This form of electromagnetic radiation has wavelengths longer than
x-rays but is still shorter than visible radiation. An active material known as
polycrystalline diamond is being used for reliable ultraviolet sensing. UV
sensors can discover the exposure of environment to ultraviolet radiation.
Criteria to select a UV Sensor
 Wavelength ranges in nanometres (nm) that can be detected by the UV
sensors.
 Operating temperature.
 Accuracy.
 Weight.
 Power range.
3.4) APPLICATIONS
 Measures the portion of the UV spectrum which sunburns
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human skin.
Pharmacy.
Automobiles.
Robotics.
Printing industry for solvent handling and dyeing
processes.
Chemical industry for the production, storage, and
transportation of chemicals.
TOUCH SENSOR
 A touch sensor acts as a variable resistor as per the
location where it is touched.
 The figure is as shown below.
 A touch sensor is made of:
 Fully conductive substance such as copper.
 Insulated spacing material such as foam or plastic.
 Partially conductive material.
APPLICATION
 Commercial – Medical, vending, Fitness and gaming.
 Appliances – Oven, Washing machine/dryers,
dishwashers, refrigerators.
 Transportation – Cockpit fabrication and streamlining
control among the vehicle manufacturer.
 Fluid level sensors.
 Industrial Automation – Position and liquid level
sensing, human touch control in automation
applications.
CONCLUSION
Owing to its wide range of applications sensor
technology is fast gaining momentum in modern day
technological world. Its applications vary from
common home appliances to highly sophisticated
electrical, electronic equipments.
REFERENCES
 Wikipedia.com
 Wiki.answers.com
 www.meas-spec.com
 Process control instrumentation technology