Smart Sensor

CONTENTS
• INTRODUCTION
• ARCHITECTURE
• FABRICATION
• ADVANTAGESAND DISADVANTAGES
• APPLICATIONS
• SUMMARY
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1. INTRODUCTION
• Sensors are devices that responds to a physical stimulus
heat, light, sound, pressure, magnetism, motion, etc , and
convert that into an electrical signal. They perform an
input function.
• Devices which perform an output function are
generally called Actuators and are used to control
some external device, for example movement.
• Both sensors and actuators are collectively known as
Transducers. Transducers are devices used to convert
energy of one kind into energy of another kind.
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SMART SENSOR
This integrated sensors which has electronics and the
transduction element together on one silicon chip, this
system can be called as system-on-chip (SoC).The
main aim of integrating the electronics and the sensor
is to make an intelligent sensor, which can be called
as smart sensor. Smart sensors then have the ability
to make some decision.
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A smart sensor is an analog/digital transducer
combined with a processing unit and a communication
interface. It consists of transduction element, signal
conditioning electronic and controller/processor that
support some intelligence in a single package.

Smart sensors / Intelligent sensor are
sensors with integrated
electronics that can perform one or
more of the following
function:[1]
1. Data Conversion
2. Bidirectional communication
3. Take decisions
4. Perform logical operations
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TYPES OF SMART SENSORS
SMART SENSOR HYBRID
Three different types of configurations are
shown in which all the components are
placed on a chip. This is called
standardization. In the first hybrid system,
a sensor is connected withADC and bus
interface with the help of universal sensor
interface. The second configuration shows
the connection of sensor analog system
with the digital circuit and bus interface. In
the third configuration, sensor is combined
with the interface circuit already to
provide duty cycle and bit stream as
shown in figure
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INTEGRATED SMART SENSORS
If we integrate all functions from sensor to bus interface in one chip, we get an
integrated smart sensor as shown in figure below.[1]
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SMART SENSOR NETWORK
A sensor network is a collection of sensors interconnected with each other by a
communication network. A sensor network is made up of individual multifunctional
sensor nodes. It has much significance like sensing accuracy, area coverage,
connectivity, minimal human interaction.
Figure below shows the elements of a single network node.
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2. SMART SENSOR ARCHITECTURE
The basic architectural components of smart sensor are listed
as follows:
 Sensing element,
 Amplifier,
 Sample and hold,
 Analog multiplexer,
 Analog to digital converter (ADC),
 Offset and temperature compensation,
 Digital to analog converter (DAC),
 Memory,
 Serial communication
 Processor
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FIVE MAIN PARTS OF SENSOR NODE ARE:
 The central unit: It is in the
form of microprocessor which
manages the tasks.
 Battery: Is the source of
energy
 A Transceiver: Interacts with
the environment and collects
data.
 Memory: Used as storage
media for storing data or
processing data.
 Communication module: It
includes transceivers and
forwards queries and data to
and from central module.
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SIGNAL PROCESSING
 The signals recorded by many sensors are typically low in
amplitude, Integration of interface electronics and signal
processing circuitry at the sensor site (monolithic or hybrid)
serves a number of functions, including signal amplification,
impedance transformation, signal filtering and buffering, and
multiplexing.
 CMOS amplifiers are perhaps the most suitable since they provide
high gain and high input impedance through a relatively simple and
compact circuit and are readily compatible with integration of
high-density digital circuitry on the same chip.
 In addition to signal amplification, impedance transformation
and signal filtering are also required.
12

DIGITAL PROCESSING & MANIPULATION
 The main circuit block required before digital control and
manipulation of sensor data can take place is the analog-
digital converter.
 Once the sensor data is digitized, a variety of signal
processing schemes can be used to correct for a number of
errors and shortcomings. These include offset cancellation,
auto-calibration, self-testing, fault detection and correction
and linearity correction.
 Auto-calibration is a very desirable function for smart
sensors. Most sensors should be adjusted for changes in
gain and offset.
 Reliability and accuracy.
13

COMMUNICATION & BUS INTERACTION
• A smart sensor should be capable of interacting with a higher
level controller that manages the overall system.
• Efforts are currently underway to develop such a standard bus for
sensor applications that is uniquely designed to optimize
functionality, speed and overall cost.
• A variety of information can be exchanged between the sensor and
the controller over the bus, including calibration and compensation
data, addresses and personality information, measured data, and
programming data initiated by the controller, the communication
interface should have the ability to receive and transmit information
over the bus at a fairly high speedit should be noted that many
sensor signals have limited bandwidth and even in the case of a
multi-sensor system, the bus data rate may be sufficient to
accommodate all sensors
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3. FABRICATION
 Transduction properties of one class of materials
and electronic properties of silicon (GaAs)
 One problem with silicon is that its sensitivities to
strain, light and magnetic field show a large cross-
sensitivity to temperature. When it is not possible
to have silicon with proper effects, it is possible to
deposit layers of materials with desired sensitivity
on the top of a silicon substrate.
made with the same
 Sensor is
integrated circuit.
technology as
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• Solid- State integrated sensors
are basically composed of
four elements namely, custom
films for transduction,
microstructures, integrated
interface circuitry and
microcomputer based signal
processing algorithms.
Mainly, three techniques bulk
micro-machining, surface
micromachining and wafer
bonding process are used for
fabrication of smart sensors
• Fig showing the fabrication
of a pressure sensor
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4. ADVANTAGES AND DISADVANTAGES
ADVANTAGES
 The smart sensor takes over the conditioning and control of the
sensor signal, reducing the load on the central control system,
allowing faster system operation.
 Direct digital control provides high accuracy, not achievable
with analog control systems and central processing.
 The cost of smart sensor systems is presently higher than that of
conventional systems, but when the cost of maintenance, ease of
programming, ease of adding new sensors is taken into account, the
long- term cost of smart sensor systems is less.
 Individual controllers can monitor and control more than one
process variable.
17

DISADVANTAGES
 If upgrading to smart sensors, care has to be taken when mixing
old devices with new sensors, since they may not be compatible.
 If a bus wire fails, the total system is down, which is not the
case with discrete wiring. However, with discrete wiring, if one
sensor connection fails, it may be necessary to shut the system
down. The problem of bus wire failure can be alleviated by the
use of a redundant backup bus.
18

5.APPLICATIONS
 INDUSTRIAL
In industries machines and equipments are monitored and
controlled for pressure, temperature , humidity level and also for
vibrations
19

 AUTOMOTIVES
Communications between engine, transmission,
suspension, braking and other controls has long
been anticipated.
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 FINGER PRINT RECOGNISITION
A fingerprint sensor is an electronic device used to capture a
digital image of the fingerprint pattern. The captured image is
called a live scan. This live scan is digitally processed to create
a biometric template (a collection of extracted features) which
is stored and used for matching.
21

 TELECOMMUNICATION
A smart card known as a Wireless Identity Module, is similar to the
Subscriber Identity Module (SIM) used on existing GSM cellular
phones. The card guarantees 100-percent security for e-commerce
transactions by providing authentication of the parties involved, by
means of encryption and digital signatures.
22

PATTERN RECOGNISITION
The sensor uses incident light or backlight to detect the
contours of an object and compares them with the
contours of one or several models in a reference image.
23

 SMART DUST
Smart dust is a hypothetical wireless network of tiny micro-
electro-mechanical (MEMS) sensors, robots, or devices, which
can detect (for example) light, temperature, or vibration. The
devices will eventually be the size of a grain of sand, or even a
dust particle, with each mote having self-contained sensing,
computation, communication and power.
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BIOMEDICAL APPLICATIONS
A number of smart sensors for biomedical applications have also
been developed by using chip technology .e.g. biochips Cyto-
sensor micro-physio-meter: biological applications of silicon
technology.
25

 MEMS AND PROCESS CONTROL
MEMS (Micro-Electro-Mechanical Systems) is a class of
systems that are physically small. These systems have both
electrical and mechanical components. MEMS originally used
modified integrated circuit (computer chip) fabrication
techniques and materials to create these very small mechanical
devices
26

SMART TOYS (ROBOTS)
These days the trend in toys is to make them as life-like as possible
which move or change directions after sensing objects around
them.
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DEFENCE APPLICATIONS
Smart cameras that can operate sophisticated software analytics
onboard the camera itself, and then report alarms remotely using
IP networking facilities. It has ability to perform object detection,
crowd pattern analysis, securezone intrusion detection, and so on
boost the efficiency and accuracy of a human operator who is
likely monitoring multiple banks of displays.
Smart sensor equipments helps in monitoring a wide variety of
parameters like EMI, fatigue loading, thermal cycling,
vibration and shock levels, acoustic emissions and corrosive
environments
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6. SUMMARY
Automization can’t be imagined without the smart sensors. These
sensors are potentially cheaper, offer higher performance and
reliability, and are much smaller in size than their discrete
counterparts. They have also been employed in applications
including transportation and health care and in large part have
fulfilled their promise.
Sensor signals can be amplified and properly processed, are
multiplexed and are buffered ready to be received by micro-
processor on these signals and offer a standard data stream to the
user thus making the entire sensing module behave like a system
periphery rather than a passive component.
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Smart Sensor

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