Internet of Things: Sensors

Introduction

 
This chapter will focus on IoT Sensors and what are IoT sensors.
 
You may wonder why it is so critical for IoT sensors that we have a separate segment.

In the functionality of IoT, sensors play a key role. The transfer of data inside the IoT notions M2M (Machine-to-Machine) and M2P (Machine-to-People) is defined by the behavior of the sensors. Most current applications use connected sensors in the context of development.
 

IoT Sensors

 
Sensors are a primary way for businesses, cities, and people that employ them for IoT purposes to understand the maximum potential for value-added. Sensors generally host a heterogeneous functional school. From variations in temperature, humidity, power, and strain to thousands of items on the factory floor, both can be observed.

Sensors may be used extensively, but in some situations, they may have to be extremely customized to resolve a variety of challenges. Sensors will have a true added benefit for IoT and ICT4D programs by this customization.
 

Range Of Common Sensors

 
The below figure illustrates some commonly found sensors available in the commercial market.
 
 
Types of Sensors
 
Sensors are often categorized based on their power sources: active v/s passive.
 
Active sensors emit energy of their own and then sense the response of the environment to that energy. Radio Detection and Ranging (RADAR) is an example of active sensing.
 
Passive sensors simply receive energy (in any form) that is produced external to the sensing device. A standard camera is embedded with a passive sensor - it receives signals in the form of light and captures them on a storage device.
 
Position Sensors
 
Position sensor measures the position of an object; the position measurement can either be in absolute terms (absolute position sensor) or in relative terms (displacement sensor). Position sensors can be linear, angular, or multi-axis.
 
Example - Potentiometer, inclinometer, proximity sensor
 
Occupancy and Motion Sensors 
 
Occupancy sensors detect the presence of people and animals in a surveillance area, while the motion sensors detect the movement of people and objects. The difference between the two is that occupancy sensors will generate a signal even when a person is stationary, while a motion sensor won't.
 
Example - Electric eye, RADAR
 
Velocity and Acceleration Sensors 
 
Velocity (speed of motion) sensors may be linear or angular, indicating how fast an object moves along a straight line or how fast it rotates. Acceleration sensors measure changes in velocity.
 
Example - Accelerometer, gyroscope
 
Force
 
Force sensors detect whether a physical force is applied and whether the magnitude of the force is beyond a threshold.
 
Example - Force gauge, viscometer, tactile sensor (touch sensor)
 
Pressure
 
Pressure sensors are related to force sensors and measure the force applied by liquids or gases. Pressure is measured in terms of force per unit area.
 
Example - Barometer, bourdon gauge, piezometer
 
Flow
 
Flow sensors detect the rate of fluid flow. They measure the volume (mass flow) or rate (flow velocity) of fluid that has passed through a system in a given period.
 
Example Anemometer, mass flow sensor, water meter
 
Acoustic
 
Acoustic sensors measure sound levels and convert that information into digital or analog data signals.
 
Example - Microphone, geophone, hydrophone
 
Humidity
 
Humidity sensors-detect humidity (amount of water vapor) in the air or a mass. Humidity levels can be measured in various ways: absolute humidity, relative humidity, mass ratio, and so on
 
Example - Hygrometer, humistor, soil moisture sensor
 
Light
 
Light sensors detect the presence of light (visible or invisible).
 
Example - Infrared sensor, photodetector, flame detector
 
Radiation
 
Radiation sensors detect radiations in the environment. Radiation can be sensed by scintillating or ionization detection.
 
Example - Geiger–Müller counter, scintillator, neutron detector
 
Temperature
 
Temperature sensors measure the amount of heat or cold that is present in a system. They can be broad of two types: contact and non-contact. Contact temperature sensors need to be in physical contact with the object being sensed. Non-contact sensors do not need physical contact, as they measure temperature through convection and radiation.
 
Example - Thermometer, calorimeter, temperature gauge
 
Chemical
 
Chemical sensors measure the concentration of chemicals in a system. When subjected to a mix of chemicals, chemical sensors are typically selective for a target type of chemical (for example, a CO2 sensor senses only carbon dioxide).
 
Biosensors
 
Biosensors detect various biological elements such as organisms, tissues, cells, enzymes, antibodies, and nucleic acids.
 
Example - Blood glucose biosensor, pulse oximetry, electrocardiograph
 

Factors Driving Adopting Sensors Within IoT

 
Three primary factors driving the adoption of sensor technology are price, capability, and size.
 
Cheaper sensors
 
The price of sensors has consistently fallen over the past several years, and these price declines are expected to continue. Sensors vary widely in price, but many are now cheap enough to support broad business applications.
 
Smarter Sensors
 
Sensor does not function by itself—it is a part of a larger system that comprises microprocessors, modem chips, power sources, and other related devices. Over the last two decades, microprocessors’ computational power has improved, doubling every three years
 
Smaller Sensors
 
There has been a rapid growth in the use of smaller sensors that can be embedded in smartphones and wearables. Micro-electro-mechanical systems (MEMS) sensors—small devices that combine digital electronics and mechanical components—have the potential to drive wider IoT applications.
 
Generic Factor To Determine The Suitability Of Sensors
 
There are, however, several generic factors that determine the suitability of a sensor for a specific application.
 
Any of these factors can impact the reliability of the data received and therefore the value of the data itself.
  1. Accuracy - A measure of how precisely a sensor reports the signal.
  2. Repeatability- A sensor’s performance in consistently reporting the same responsewhen subjected to the same input under constant environmentalconditions.
  3. Range - The band of input signals within which a sensor can perform accurately. Input signals beyond the range lead to inaccurate output signals and potential damage to sensors.
  4. Noise - The fluctuations in the output signal resulting from the sensor or the external environment.
  5. Resolution- The smallest incremental change in the input signal that the sensorrequires to sense and report a change in the change in the outputsignal.
  6. Selectivity - The sensor’s ability to selectively sense and report a signal.
Sensor Connectivity
 
The connectivity requirements of different types of IoT networks vary widely, depending on their purpose and resource constraints. A range of different wireless and wireline technologies can be used to provide full IoT connectivity.
 
IoT devices communicate using a range of different communication protocols, which may include: short-range radio protocols (such as ZigBee, Bluetooth, and Wi-Fi); mobile networks; or longer-range radio protocols (such as LoRa). These technologies can be segmented based on wireless versus wireline and wireless technologies can be grouped by personal area network (WPAN), wireless local area network (WLAN) or wide area network (WWAN) technologies.
 
 
Some examples of Sensors are:
  • DHT11 Temperature and Humidity Sensor, DHT22 Digital Temperature and Humidity Sensor, Temperature Sensor LM35, Digital Temperature sensor
  • Motion sensor
  • Ultrasonic Range Finder Module sensor
  • Sound Detection sensor
  • Photosensitive Resistor sensor
  • Pressure sensor
  • RF IC card sensor
  • Antenna
  • Camera Image Sensor
  • Carbon Monoxide Detecting Sensor, Air Quality Gas Sensor, Gas Sensor - Methane, Butane, LPG, smoke Sensor, Infrared Flame Sensor, Smoke Sensor, Liquefied Petroleum Gas Sensor
  • Proximity sensor
  • Digital Touch Sensor, Touch PAD sensor
  • Vibration sensor
  • Rain Sensitive sensor/ Rain Drop Detection Sensor/ RainDrops Humidity Sensor

Comparing IoT Sensor Connectivity Technologies

 
Each technology has distinct characteristics, including the range of their signal, the extent of their data, Throughput (or bandwidth), and the power needs of the communications device (or battery life), among other attributes.
 
  Personal Area Network ANT + Bluetooth + RFID + NFC 802.11.4 + ZigBee Local Area Networks(/WLAN)+ WiFi Wide Area Network(WWAN) Wireline(Copper/DSL/Ethernet/Coaxial/Fiber
Range Short Intermediate Long Long
Bandwidth Narrow Broad Intermediate/Broad Intermediate
Battery Life Long Short Intermediate Short
 
That's all from this chapter, hope you enjoyed it.
Author
Tejas Trivedi
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