A sensor is a device that detects and responds to some type of input from the physical environment. The specific input could be light, heat, motion, moisture, pressure, or any one of a great number of other environmental phenomena. The output is generally a signal that is converted to human-readable display at the sensor location or transmitted electronically over a network for reading or further processing. 

1. SENSORS AND ITS TYPES
By: Nutronics India1

2. WHAT ARE SENSORS?
 A sensor is a device that detects and
responds to some type of input from
the physical environment.
 The specific input could be light, heat,
motion, moisture, pressure, or any one
of a great number of other
environmental phenomena.
 The output is generally a signal that is
converted to human-readable display
at the sensor location or transmitted
electronically over a network for
reading or further processing.
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3. CRITERIA TO CHOOSE A SENSOR
 There are certain features which have to be considered when
we choose a sensor. They are as given below:
 Accuracy
 Environmental condition – usually has limits for temperature/
humidity
 Range – Measurement limit of sensor
 Calibration – Essential for most of the measuring devices as the
readings changes with time
 Resolution – Smallest increment detected by the sensor
 Cost
 Repeatability – The reading that varies is repeatedly measured
under the same environment 3

4. TYPES OF SENSORS
 Temperature – Thermistors, thermocouples, RTD’s, IC and many more.
 Pressure – Fibre optic, vacuum, elastic liquid based manometers, LVDT, electronic.
 Flow – Electromagnetic, differential pressure, positional displacement, thermal mass, etc.
 Level Sensors – Differential pressure, ultrasonic radio frequency, radar, thermal
displacement, etc.
 Proximity and displacement – LVDT, photoelectric, capacitive, magnetic, ultrasonic.
 Biosensors – Resonant mirror, electrochemical, surface Plasmon resonance, Light
addressable potentio-metric.
 Image – Charge coupled devices, CMOS
 Gas and chemical – Semiconductor, Infrared, Conductance, Electrochemical.
 Acceleration – Gyroscopes, Accelerometers.
 Others – Moisture, humidity sensor, Speed sensor, mass, Tilt sensor, force, viscosity.
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5. SENSORS SOLD BY NUTRONICS INDIA
 Temperature Sensors
 This device collects information 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 element for the
temperature measurement. The position of the mercury is
observed by the viewer to measure the temperature.
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7.  Humidity Sensor
 A humidity sensor (or
hygrometer) senses,
measures and reports both
moisture and air
temperature.
 The ratio of moisture in the
air to the highest amount of
moisture at a particular air
temperature is called
relative humidity.
 Relative humidity becomes
an important factor, when
looking for comfort.
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8.  pH Sensors
 pH sensor basically works on the fact that interface of
two liquids produces a electric potential which can be
measured.
 In other words when a liquid inside an enclosure made
of glass is placed inside a solution other than that liquid,
there exists an electrochemical potential between the
two liquids.
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