sensors full ppt 2023

1. Sensors
Balakrishna G

2. Table Contents
– Definition
– Introduction
– History of Sensors
– Choosing a Sensor
– Classification of Sensors
– Types of Sensors
– Applications
– Trends and recent research
– Conclusion
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3. Sensors?
• American National Standards Institute
– A device which provides a usable output in response to a specified measurand
• A sensor acquires a physical quantity and converts it into a signal
suitable for processing (e.g. optical, electrical, mechanical)
• Nowadays common sensors convert measurement of physical
phenomena into an electrical signal
• Active element of a sensor is called a transducer

4. Transducer?
A device which converts one form of energy to another
When input is a physical quantity and output electrical → Sensor
When input is electrical and output a physical quantity → Actuator
e.g. Piezoelectric:
Actuators
Sensors
Physical
parameter
Electrical
Output
Electrical
Input
Physical
Output
Force -> voltage
Voltage-> Force
=> Ultrasound!
Microphone, Loud Speaker

5. Sensors?
• American National Standards Institute
– A device which provides a usable output in response to
a specified measurand
• A sensor acquires a physical quantity and converts it into
a signal suitable for processing (e.g. optical, electrical,
mechanical)
• Nowadays common sensors convert measurement of
physical phenomena into an electrical signal
• Active element of a sensor is called a transducer

6. Transducer?
A device which converts one form of energy to another
When input is a physical quantity and output electrical → Sensor
When input is electrical and output a physical quantity → Actuator
e.g. Piezoelectric:
Actuators
Sensors
Physical
parameter
Electrical
Output
Electrical
Input
Physical
Output
Force -> voltage
Voltage-> Force
=> Ultrasound!
Microphone, Loud Speaker

7. History of Sensors
7

8. Commonly Detectable Phenomena
•Chemical
•Electric
•Electromagnetic
•Heat/Temperature
•Magnetic
•Mechanical motion (displacement, velocity, acceleration, etc.)
•Optical
•Radioactivity
•Biological

9. Common Conversion Methods
•Physical
–thermo-electric, thermo-elastic, thermo-magnetic,
thermo-optic
–photo-electric, photo-elastic, photo-magnetic,
–electro-elastic, electro-magnetic
–magneto-electric
•Chemical
–chemical transport, physical transformation, electro-
chemical
•Biological
–biological transformation, physical transformation

10. Categorize sensors into different types:
Temperature sensors
Pressure sensors
Proximity sensors
Motion sensors
Light sensors
Sound sensors
Gas sensors
Image sensors
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11. Commonly Measured Quantities
Stimulus Quantity
Acoustic Wave (amplitude, phase, polarization),
Spectrum, Wave Velocity
Biological & Chemical Fluid Concentrations (Gas or Liquid)
Electric Charge, Voltage, Current, Electric Field
(amplitude, phase, polarization),
Conductivity, Permittivity
Magnetic Magnetic Field (amplitude, phase,
polarization), Flux, Permeability
Optical Refractive Index, Reflectivity, Absorption
Thermal Temperature, Flux, Specific Heat, Thermal
Conductivity
Mechanical Position, Velocity, Acceleration, Force,
Strain, Stress, Pressure, Torque

12. Definition
It is a device that converts signals from one
energy domain to electrical domain.
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15. Choosing a Sensor

16. Need forSensors
• Sensors are pervasive. They are embedded in
our bodies, automobiles, airplanes, cellular
telephones, radios, chemical plants, industrial
plants and countless other applications.
• Without the use of sensors, there would be no
automation !!
– Imagine having to manually fill Poland Spring
bottles

17. Classification of Sensors
In the first classification of the sensors, they
are divided in to Active and Passive.
• Active Sensors are those which require an
external excitation signal or a power signal.
• Passive Sensors, on the other hand, do not
require any external power signal and
directly generates output response.
●●●
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18. Classification of Sensors
The next classification is based on conversion
phenomenon
• i.e., the input and the output. Some of the
common conversion phenomena are
Photoelectric, Thermoelectric,
Electrochemical, Electromagnetic, Thermo-
optic, etc.
●●●
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19. Classification of Sensors
• Analog Sensors produce an analog output i.e.,
a continuous output signal (usually voltage but
sometimes other quantities like Resistance
etc.) with respect to the quantity being
measured.
• Digital Sensors, in contrast to Analog Sensors,
work with discrete or digital data. The data in
digital sensors, which is used for conversion
and transmission, is digital in nature.
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20. Types of Sensors
Temperature Sensor
• One of the most common and most
popular sensors is the Temperature
Sensor. A Temperature Sensor, as the
name suggests, senses the temperature
i.e., it measures the changes in the
temperature.
●●●
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21. Temperature Sensor: Bimetallic Strip
• Bimetallic Strip
L = L0[1+ β(T -T0)]
• Application
– Thermostat (makes or
breaks electrical
connection with
deflection)

22. Temperature Sensor: RTD
• Resistance temperature device
(RTD)
R = R0[1+α(T -T0)]
 0 
R = R0e T
T 
γ
 1
−
1 

23. Other Temperature Sensors
• Thermistor
T h er mi
⏟
s
t
o
r
• Thermocouple: Seeback effect to
transform a temperature difference to a
voltage difference
Resistor
Thermal
R  exp
 Eg
 2kT 

 

24. Types of Sensors
Proximity Sensors
• A Proximity Sensor is a non-contact type
sensor that detects the presence of an object.
Proximity Sensors can be implemented using
different techniques like Optical (like Infrared
or Laser), Sound (Ultrasonic), Magnetic (Hall
Effect), Capacitive, etc.
●●●
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25. Light Sensor
• Light sensors are used in
cameras, infrared detectors, and
ambient lighting applications
• Sensor is composed of
photoconductor such as a
photoresistor, photodiode, or
phototransistor

26. Photoresistors
• Light sensitive variable resistors.
• Its resistance depends on the intensity of light incident upon it.
– Under dark condition, resistance is quite high (M: called dark resistance).
– Under bright condition, resistance is lowered (few hundred ).
• Response time:
– When a photoresistor is exposed to light, it takes a few milliseconds, before it
lowers its resistance.
– When a photoresistor experiences removal of light, it may take a few seconds
to return to its dark resistance.
• Photoresisotrs exhibit a nonlinear characteristics for incident optical illumination
versus the resulting resistance.
Symbol
log10 R =α − β log10 P
R
104
103
102
101
101 102 103 104
Relative illumination (P)

27. Types of Sensors
Infrared Sensor (IR Sensor)
• IR Sensors or Infrared Sensor are light
based sensor that are used in various
applications like Proximity and Object
Detection. IR Sensors are used as proximity
sensors in almost all mobile phones.
●●●
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28. Types of Sensors
Light Sensor
• Sometimes also known as Photo Sensors, Light
Sensors are one of the important sensors. A
simple Light Sensor available today is the Light
Dependent Resistor or LDR.
• The property of LDR is that its resistance is
inversely proportional to the intensity of the
ambient light i.e., when the intensity of light
increases, its resistance decreases and vise-versa.
●●●
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29. Types of Sensors
Smoke and Gas Sensors
• One of the very useful sensors in safety
related applications are Smoke and Gas
Sensors.
• Almost all offices and industries are
equipped with several smoke detectors,
which detect any smoke (due to fire) and
sound an alarm.
●●●
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30. Types of Sensors
Alcohol Sensor
• As the name suggests, an Alcohol Sensor
detects alcohol. Usually, alcohol sensors are
used in breathalyzer devices, which determine
whether a person is drunk or not.
• Law enforcement personnel uses breathalyzers
to catch drunk-and-drive culprits.
●●●
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31. Types of Sensors
Touch Sensor
• We do not give much importance to touch
sensors but they became an integral part of
our life.
• Whether you know or not, all touch screen
devices (Mobile Phones, Tablets, Laptops,
etc.) have touch sensors in them
●●●
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32. Types of Sensors
Color Sensor
• A Color Sensor is an useful device in building color
sensing applications in the field of image
processing, color identification, industrial object
tracking etc.
• The TCS3200 is a simple Color Sensor, which can
detect any color and output a square wave
proportional to the wavelength of the detected
color.
●●●
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33. Types of Sensors
Humidity Sensor
• If you see Weather Monitoring Systems, they
often provide temperature as well as humidity
data.
• So, measuring humidity is an important task in
many applications and Humidity Sensors help
us in achieving this.
●●●
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34. Types of Sensors
Tilt Sensor
• Often used to detect inclination or orientation,
Tilt Sensors are one of the simplest and
inexpensive sensors out there.
• Previously, tilt sensors are made up of Mercury
(and hence they are sometimes called as
Mercury Switches) but most modern tilt
sensors contain a roller ball.
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35. Magnetic Field Sensor
• Magnetic Field sensors are
used for power steering,
security, and current
measurements on
transmission lines
• Hall voltage is proportional
to magnetic field
n q t
I  B
H
V =

36. Ultrasonic Sensor
• Ultrasonic sensors are used for position measurements
• Sound waves emitted are in the range of 2-13 MHz
• Sound Navigation And Ranging (SONAR)
• Radio Dection And Ranging (RADAR) –
ELECTROMAGNETIC WAVES !!
15° - 20°

37. Photogate
• Photogates are used in
counting applications (e.g.
finding period of period
motion)
• Infrared transmitter and
receiver at opposite ends of
the sensor
• Time at which light is broken
is recorded

38. Sensors crucial factors
•Sensitivity, Resolution, accuracy and
precision
•Uncertainty is referred to as an error.
• Accuracy and precision are two important
factors to consider while taking
measurements.
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39. Sensors crucial factors
• Sensitivity deals with responsiveness
• Resolution with the smallest detectable change
• Accuracy with closeness to the true value
• Precision with consistency in measurements.
Each of these aspects is crucial in determining the
reliability, usefulness, and applicability of sensor
measurements in various fields and applications.
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40. Trends and recent research directions
in sensor technology :
1. Internet of Things (IoT) Sensors: IoT has been a driving force in
sensor technology. Advancements in miniaturization, low-power
consumption, and wireless connectivity have led to the
development of sensors for various applications, including smart
homes, healthcare, agriculture, and industrial monitoring.
2. Environmental Sensors: There has been a growing focus on
developing sensors to monitor environmental parameters such as
air quality, water quality, and soil conditions. These sensors aim to
provide real-time data to address environmental concerns and
support sustainability efforts.
3. Biomedical Sensors: Research in biomedical sensors has been
extensive, with a focus on wearable sensors for continuous health
monitoring, point-of-care diagnostic devices, and implantable
sensors for monitoring specific health conditions. These sensors
aim to improve healthcare by enabling early disease detection
and personalized medicine.
4. Advanced Imaging Sensors: Advancements in imaging sensors,
including those used in cameras, LiDAR (Light Detection and
Ranging), and hyperspectral imaging, have enabled higher
resolution, faster data acquisition, and improved accuracy for
various applications like autonomous vehicles, medical imaging,
and agriculture.
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41. 5. Flexible and Stretchable Sensors: Researchers have been
working on developing sensors that can bend, stretch, and
conform to various surfaces. These flexible and stretchable
sensors have potential applications in wearable electronics,
robotics, and human-machine interfaces.
6. Nanotechnology in Sensors: Utilizing nanomaterials and
nanotechnology has led to the development of highly sensitive
and selective sensors. Nanoscale sensors offer improved
detection limits and can be used in areas such as gas sensing,
environmental monitoring, and healthcare diagnostics.
7. Energy Harvesting Sensors: Efforts are ongoing to create self-
powered or energy-efficient sensors that can harvest energy
from their environment (such as vibrations, light, or
temperature gradients). These sensors aim to reduce reliance
on external power sources and prolong operational lifetimes.
8. Machine Learning and Sensor Fusion: Integration of machine
learning algorithms and sensor fusion techniques has
enhanced the capabilities of sensors in interpreting complex
data patterns, reducing noise, and improving accuracy in
various applications like robotics, autonomous systems, and
predictive maintenance.
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42. Applications
Various applications of sensors in different
industries:
•Automotive
•Healthcare
•Consumer electronics
•Industrial automation
•Environmental monitoring

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58. Conclusion
✓ A sensor is a device that detects the change in the
environment and responds to some output on the
other system.
✓ A sensor converts a physical phenomenon into a
measurable analog voltage (or sometimes a
digital signal) converted into a human-readable
display or transmitted for reading or further
processing.
✓ Sensors are central to industrial applications
being used for process control, monitoring, and
safety.
✓ Sensors are also central to medicine being used
for diagnostics, monitoring, critical care, and
public health.
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