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Sensors are devices used to provide information on the
presence or absence of an object.
Sensors such as photoelectric, inductive, capacitive, and
ultrasonic change their output when an object is present
without touching the sensor.
Sensors are capable of manipulation and computation of
the sensor-derived data.
Sensors simply take physical, biological or chemical input
& convert it to the measured value into a digital format.
Sensors are made from silicon to make them low cost.
MUG WITH TEMPERATURE
WHAT IS SMART SENSOR ?
Smart sensors are defined by the IEEE 1451 standard
as sensors with small memory and standardized physical
connection to enable the communication with processor
and data network.
A sensor producing an electrical output when combined
with interfacing electronic circuits is known as “Smart
It is a combination of both sensor and actuator.
[sensor + interfacing circuit = smart sensor]
Capable of logic functions, two-way communication and
WHY SMART SENSOR ?
Self calibration: Adjust deviation of output of sensor
from desired value.
Communication: Broadcast information about its own
Computation: Allows one to obtain the average,
variance and standard deviation for the set of
Multisensing: 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.
WHAT IS INTELLIGENT SENSOR ?
The intelligent sensor concept is based on adding the
possibility of processing the sensor data, the flexibility to
reconfigure embedded functions, and also to aggregate
external sensors’ data.
Since it is an evolution of smart sensors, no penalties in term
of cost and performance are expected.
The outcome is the combination of a sensor, a small
microcontroller, the necessary memory– flash, RAM and ROM,
and an optimized architecture for sensor applications.
The main issue of the intelligent sensor is the software
partitioning with the applications processor since this
concept is new to most software engineers.
MORE ABOUT INTELLIGENT
The intelligent sensor structure in an application enables the
customization of the embedded algorithms to specific
applications; moreover, the customization can happen by
reprogramming the flash(memory).
Since a microcontroller is available, the management and
control of external sensors- basic or smart sensors- or external
devices- like LEDs- is now possible.
An optimized architecture with atleast two digital interfaces,
master and slave and one analog input are necessary to
respond to this extra functionality.
The key constraints are relative to existing sensors: not to
exceed the form factor of an existing sensor, minimize the
extra cost and equivalent inner power consumption.
EVOLUTION- SMART 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.
THIRD 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 micro chip.
FOURTH GENERATION SENSORS
Memory cells for calibration and temperature compensation data
are added to the elements of the 3rd MEMS sensor generation.
FIFTH GENERATION SENSORS
This generation sensors are equivalent to intelligent sensors.
APPLICATIONS OF SMART
Accelerometer: It consists of the sensing element and electronics
on silicon. The accelerometer itself is a metal-coated SiO2 cantilever
beam that is fabricated on silicon chip where the capacitance
between the beam and the substrate provides the output signal.
Optical sensor: Optical sensor is one of the examples of smart
sensor, which are used for measuring exposure in cameras, optical
angle encoders and optical arrays. Similar examples are load cells
silicon based pressure sensors.
Infrared detector array: It was developed at solid laboratory of
University of Michigan. Here, infrared sensing element was
developed using polysilicon.
Integrated multisensor: It was developed in university of California.
This chip contains MOS devices for signal conditioning with on chip
Geological mapping: It is needed mainly to detect the minerals on
the geological areas. 14
ADVANTAGES & DISADVANTAGES
OF SMART SENSORS
Easy to Design, Use and
Small Rugged Packaging
The smart sensor consists of
both actuators & sensors, so it
is more complex than other
The complexity is much higher
in the wired smart sensors, as a
consequence the costs are also
Sensor calibration has to be
managed by an external
functions have to be given
during the design of the smart
Next smart sensors generation; S.Gervais-Ducouret; Digital Object
Identifier: 10.1109/SAS.2011.5739775; Publication Year: 2011,
IEEE P1451.1 D1.83, Draft Standard for a Smart Transducer
Interface for Sensors and Actuators Network Capable Application
Processor (NCAP) Information Model, 1996: Institute of Electrical
and Electronics Engineers, Inc.
R. N. Johnson, "Plug-and-play networked smart transducers",
Introduction to Instrumentation, Sensors, and Process Control by:
William C. Dunn
MEMS Mechanical Sensors by: Stephen Beeby, Graham Ensell,
Michael Kraft, and Neil White