Basic Sensors Technology

PRESENTED BYK.VIVEK KUMAR (EEE)

SENSORS

SENSORSIntroWhy we learn about Sensors?What are the selection criteria for Sensors?Types of SensorsApplicationsDrawbacks of SensorsWhy we switch to Smart Sensors?Conclusion

Physical Quantity Sensor Electrical

Quantity

Typical Type of Basic Sensor

Sensors: Sensors are as an electrical device that consists of components that are used to measure any other physical quantities (temperature, light, pressure, etc.) And its produce electrical signals - usually voltage or current signals, that can be used to determine the values for appropriate physical quantity.

Why we learn about Sensors? Electrical engineers need to know about sensors because they produce

electrical signals.  These electric signals are needed to be converted to a digital format.  Electrical Engineers should need to know about how to design a sensor for

their fields. Mechanical, civil, chemical and bio engineers should be used as sensors to

when they make as different measurements (temperature and other quantities). 

They need to know about them in order to select appropriate sensors to make measurements of many different physical quantities.

Engineers should designs a compact size of sensor and it can be used in various fields of applications.

For Example:Wireless Sensor Network System

What are the selection criteria for Sensors?There are certain features which have to be considered when we choose a sensor. They are as given below: Accuracy – should be HighStability - maintain under abnormal conditionEnvironmental condition - usually has limits for temperature & humidityRange - Measurement limit of sensor Calibration - Essential for most of the measuring devices as the readings changes with timeResolution - Smallest increment detected by the sensorCost - Should be LowPower Consumptions - LowRepeatability - The reading that varies is repeatedly measured under the same environment 

Temperature sensorsLight sensorsUltra sonic sensorsPressure sensors IR sensorsBiosensorsMagnetic sensorsAnalog Sound SensorVibration Sensor

Some of the few sensors are mentioned as belows:Types of Sensors:

Water Level Sensor

LDR Sensor

Analog Sound Sensor

Electricity Sensor

Current Sensor

Examples of Sensors:

Temperature sensors: Temperature is the most common of all physical measurements. We

have temperature measurement-and-control units, called thermostats. In our home heating systems, refrigerators, air conditioners, and

ovens. Temperature sensors are used on circuit boards, as part of thermal

tests, in industrial controls, and in room controls such as in calibration labs and data centers.

Though there are many types of temperature sensors, most are passive devices:

Thermocouples RTDs (Resistance Temperature Detectors), and Thermistors(Thermal Resistors)

Proximity Sensor:This is a type of sensor which can detect the presence of a

nearby object within a given distance, without any physical contact.

The working principle of a Proximity sensor is simple. A transmitter transmits an electromagnetic radiation or creates an electrostatic field and a receiver receives and analyzes the return signal for interruptions.

There are different types of Proximity sensors and the researchers will discuss only a few of them which are generally used in robots.

Sensor operation:small prism-shaped sample of single-crystal undoped GaAs attached to ends of two

optical fiberslight energy absorbed by the GaAs crystal depends on temperaturepercentage of received vs. transmitted energy is a function of temperatureIt can be made small enough for biological implantation

FIBER OPTIC TEMPERATURE SENSOR

Fiber-optic Temperature Sensor

Applications:Sensors are used in many industrial and home appliances:Wireless Sensor NetworkWater Level IndicatorLaser Security AlarmFiring Alarm SensorAutomatic Braking and Speed Control MechanismSmart Phone Touch ScreenRailway Gate Control MechanismFully Automation Control System

Drawbacks of Sensors:Some of the drawbacks occurs in sensors while its in

working condition:Life time becomes less due to over usagesEasily affected by external source such as noise, magnetic

interference, etc.Due to noise and any other interference, low Stability &

Sensitivity may leads to system failure.Some sensor may face complexity while contact with

some physical quantitiesMore Expensive in RTD sensor than Thermocouples

Why we switch to Smart Sensors?Smart sensor means a sensor with built-in signal processing &

communicatione.g., combining a “dumb sensor” and a microprocessorA Smart Sensor can be defined as a sensor with signal conditioning

circuitary with an integrated circuit which is considered as a single device.

Mainly Smart Sensors have some advantages than using ordinary sensors.Features of Smart Sensor:Linearize its own outputIncludes self calibration facilityCompensates the environmental changes

Typical Smart Sensor:A Typical Smart Sensor is given as:

SENSOR ADC MICROPROCESSOR

MEMORY

COMPUTERIZED

CONTROL ROOM

INPUTPHYSICAL QUANTITY

ELECTRICAL QUANTITY

Conclusion:Sensors are one of the most useful technology for all and also it is very efficient technology in nowadays. So Engineers should always keep in mind, while designing or creating a new type of sensors or any things, that should be satisfying the followings:

Materials should be avail as CheapSimple

Low CostLow Power Consumptions

High ReliableCompact

QUESTIONS……??????

THANKS TO ALL….!!!