Sensors are sophisticated devices that are
frequently used to detect and respond to electrical
or optical signals. A Sensor converts the physical
parameter (for example: temperature, blood
pressure, humidity, speed, etc.) into a signal which
can be measured electrically.
Sensors are made from silicon.
3. Features of a sensor
Range - Measurement limit of sensor
level of Calibration
4. Classification of sensors
Primary Input quantity (Measurand)
Transduction principles (Using physical and
Material and Technology
5. Types of sensors
6. Smart sensor
A smart sensor is a device that takes input from the
physical environment and uses built-in compute
resources to perform predefined functions upon
detection of specific input and then process data
before passing it on.
It is a combination of both sensor and actuator.
[sensor + interfacing circuit = smart sensor]
Capable of logic functions, two-way communication
and making decisions.
Accuracy level is very high.
7. Classification of smart sensor
Based on sensor
Temperature & Humidity Sensors
Based on technology
MEMS-based smart sensors
CMOS-based smart sensors
8. Based on Component:
Analog To Digital Converters (ADCs)
Digital To Analog Converters (DACs)
Based on Network Connectivity:
9. Properties of smart sensors
Self calibration: Adjust deviation of output of sensor
from desired value.
Communication: Broadcast information about its
Computation: Allows one to obtain the average,
variance and standard deviation for the set of
Multi-sensing: A single smart sensor can measure
pressure, temperature, humidity, gas flow and infrared
chemical reaction surface acoustic vapour etc.
Cost improvement: less hardware and reduction of
repetitive testing make smart sensor cost effective
11. The sensor sense the object and it’s output is created in
the form of analog signals.
Using the ADC ,the analog signal is converted in
After the conversion the signal can be easily
12. Evolution of sensors
First generation devices had little, if any, electronics
associated with them. Had MEMS sensor element
(mostly based on a silicon structure) and sometimes
combined with analog amplification on a micro chip.
Second generation sensors were part of purely
analog systems with virtually all of the electronics
remote from the sensor. Had MEMS sensor element
combined with analog amplification and analog-to-
digital converter on one micro chip.
13. 3rd generation sensors
Fusion of the sensor element with analog amplification,
analog-to-digital converter and digital intelligence for
linearization and temperature compensation on the same
14. 4th generation sensors
Memory cells for calibration and temperature
compensation data are added to the elements of
the 3rd MEMS sensor generation.
Minimum Interconnecting Cables.
Easy to Use and Maintain.
Small Rugged Packaging.
Small in size.
The smart sensor consists of both actuators & sensors,
so it is more complex than other simple sensors.
The complexity is much higher in the wired smart
sensors, as a consequence the costs are also higher.
Sensor calibration has to be managed by an external
Predefined embedded functions have to be given
during the design of the smart sensor.