What is Sensors And Types of Sensors

What is Sensors And Types of Sensors :- Generally, sensors are used in the architecture of IoT devices. Sensors are used for sensing things and devices etc. A device that provides a usable output in response to a specified measurement.

The sensor attains a physical parameter and converts it into a signal suitable for processing (e.g. electrical, mechanical, optical) the characteristics of any device or material to detect the presence of a particular physical quantity.

The output of the sensor is a signal which is converted to a human-readable form like changes in characteristics, changes in resistance, capacitance, impedance etc.

What is Sensors And Types of Sensors

Sensor is an optical device that collects data from our real world data and converts it into electrical signal.

What is the Transducer

A transducer converts a signal from one physical structure to another. It converts one type of energy into another type. It might be used as actuators in various system.

Characteristics Of Sensors

There are the followings Characteristics Of Sensors

• (1). Static characteristics
• Accuracy
• Range
• Resolution
• Precision
• Sensitivity
• Linearity
• Drift
• Repeatability
• (2). Dynamic Characteristics:
• Zero-order system
• First-order system
• Second-order system

(1). Static characteristics

It is about how the output of a sensor changes in response to an input change after steady state condition.

• Accuracy:– Accuracy is the capability of measuring instruments to give a result close to the true value of the measured quantity. It measures errors. It is measured by absolute and relative errors. Express the correctness of the output compared to a higher prior system. Absolute error = Measured value – True value
  Relative error = Measured value/True value

• Range:- Gives the highest and the lowest value of the physical quantity within which the sensor can actually sense. Beyond these values, there is no sense or no kind of response. e.g. RTD for measurement of temperature has a range of -200°C to 800°C.

• Resolution:- Resolution is an important specification towards selection of sensors. The higher the resolution, the better the precision. When the accretion is zero, it is called threshold. Provides the smallest changes in the input that a sensor is able to sense.

• Precision:- It is the capacity of a measuring instrument to give the same reading when repetitively measuring the same quantity under the same prescribed conditions. It implies agreement between successive readings, NOT closeness to the true value. It is related to the variance of a set of measurements. It is a necessary but not sufficient condition for accuracy.

• Sensitivity:- Sensitivity indicates the ratio of incremental change in the response of the system with respect to incremental change in input parameters. It can be found from the slope of the output characteristics curve of a sensor. It is the smallest amount of difference in quantity that will change the instrument’s reading.

• Linearity:- The deviation of the sensor value curve from a particular straight line. Linearity is determined by the calibration curve. The static calibration curve plots the output amplitude versus the input amplitude under static conditions. A curve’s slope resemblance to a straight line describes the linearity.

• Drift:- The difference in the measurement of the sensor from a specific reading when kept at that value for a long period of time.

• Repeatability:- The deviation between measurements in a sequence under the same conditions. The measurements have to be made under a short enough time duration so as not to allow significant long-term drift.

(2). Dynamic Characteristics

• Zero-order system:- The output shows a response to the input signal with no delay. It does not include energy-storing elements. Ex. potentiometer measure, linear and rotary displacements.

• First-order system:- When the output approaches its final value gradually it consists of an energy storage and dissipation element.

• Second-order system:- Complex output response. The output response of the sensor oscillates before steady state.

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Classification of Sensor

(1). Passive Sensor:- Can not independently sense the input. Ex- Accelerometer, soil moisture, water level and temperature sensors.

(2). Active Sensor:- Independently sense the input. Example- Radar, sounder and laser altimeter sensors.

(3). Analog Sensor:- The response or output of the sensor is some continuous function of its input parameter. Ex- Temperature sensor, LDR, analog pressure sensor and analog hall effect.

(4). Digital sensor:- Response in binary nature. Design to overcome the disadvantages of analog sensors. Along with the analog sensor, it also comprises extra electronics for bit conversion.
Example – Passive infrared (PIR) sensor and digital temperature sensor(DS1620).

(5). Scalar sensor:- Detects the input parameter only based on its magnitude. The answer for the sensor is a function of the magnitude of some input parameter. Not affected by the direction of input parameters. Example – temperature, gas, strain, color and smoke sensor.

(6). Vector sensor:- The response of the sensor depends on the magnitude of the direction and orientation of the input parameter. Example – Accelerometer, gyroscope, magnetic field and motion detector sensors.

Types of Sensors

Following are the different types of sensors with their use cases:-

• (1). Temperature Sensors
• (2). Humidity Sensors
• (3). Pressure Sensors
• (4). Proximity Sensors
• (5). Level Sensors
• (6). Accelerometers Sensors
• (7). Gyroscope Sensor
• (8). Gas Sensors
• (9). Infrared Sensors
• (10) Optical Sensors

(1). Temperature Sensors

Temperature sensors measure the amount of heat energy in a source, allowing them to detect temperature changes and convert these changes to data.

]Machinery used in manufacturing often requires environmental and device temperatures to be at specific levels. Similarly, within agriculture, soil temperature is a key factor for crop growth.

(2). Humidity Sensors

These types of sensors measure the amount of water vapor in the atmosphere of air or other gases. Humidity sensors are commonly found in heating, vents and air conditioning (HVAC) systems in both industrial and residential domains.

They can be found in many other areas including hospitals, and meteorology stations to report and predict weather.

(3). Pressure Sensors

A pressure sensor senses changes in gases and liquids. When the pressure changes, the sensor detects these changes, and communicates them to connected systems.

Common use cases include leak testing which can be a result of decay. Pressure sensors are also useful in the manufacturing of water systems as it is easy to detect fluctuations or drops in pressure.

(4). Proximity Sensors

Proximity sensors are used for non-contact detection of objects near the sensor. These types of sensors often emit electromagnetic fields or beams of radiation such as infrared.

Proximity sensors have some interesting use cases. In retail, a proximity sensor can detect the motion between a customer and a product in which he or she is interested.

The user can be notified of any discounts or special offers of products located near the sensor. Proximity sensors are also used in the parking lots of malls,

stadiums and airports to indicate parking availability. They can also be used on the assembly lines of chemical, food and many other types of industries.

(5). Level Sensors

Level sensors are used to detect the level of substances including liquids, powders and granular materials.

Many industries including oil manufacturing, water treatment, beverage and food manufacturing factories use level sensors.

Waste management systems provide a common use case, level sensors can detect the level of waste in a garbage can or dumpster.

(6). Accelerometers Sensors

Accelerometers detect an object’s acceleration i.e. the rate of change of the object’s velocity with respect to time. Accelerometers can also detect changes to gravity.

Use cases for accelerometers include smart pedometers and monitoring driving fleets. They can also be used as anti-theft protection alerting the system if an object that should be stationary is moved.

(7). Gyroscope Sensor

Gyroscope sensors measure the angular rate or velocity, often defined as a measurement of speed and rotation around an axis.

Use cases include automotive, such as car navigation and electronic stability control (anti skid) systems. Additional use cases include motion sensing for video games, and camera-shake detection systems.

(8). Gas Sensors

These types of sensors monitor and detect changes in air quality, including the presence of toxic, combustible or hazardous gasses.

Industries using gas sensors include mining, oil and gas, chemical research and manufacturing. A common consumer use case is the familiar carbon dioxide detectors used in many homes.

(9). Infrared Sensors

These types of sensors sense characteristics in their surroundings by either emitting or detecting infrared radiation. They can also measure the heat emitted by objects.

Infrared sensors are used in a variety of different IoT projects including healthcare as they simplify the monitoring of blood flow and blood pressure.

Televisions use infrared sensors to interpret the signals sent from a remote control. Another interesting application is that of art historians using infrared sensors to see hidden layers in paintings to help determine whether a work of art is original or fake or has been altered by a restoration process.

(10) Optical Sensors

Optical sensors convert rays of light into electrical signals. There are many applications and use cases for optical sensors. In the auto industry, vehicles use optical sensors to recognize signs, obstacles, and other things that a driver would notice when driving or parking. Optical sensors play a big role in the development of driverless cars. Optical sensors are very common in smart phones. For example, ambient light sensors can extend battery life. Optical sensors are also used in the biomedical field including breath analysis and heart-rate monitors.

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