What Are IoT Sensors? (Beginner’s Guide)

IoT Sensors

Have you ever asked yourself the question: “what are IoT sensors?”

The internet of things may be a new trending topic in today’s world however IoT sensors have been around for decades for the most part.

How is this possible?

IoT sensors are simply electronic sensors with a more modern meaning.

To further understand how these sensors collect and share data then here I will cover the subject in a little more detail.


Trying to find all of your information about IoT in one place is not always easy due to the number of different job roles involved in the subject.

The following list describes just some of the technical job roles that you may encounter in a IoT project:


  • Electronic Engineers will usually work with sensors and other electronic components.
  • Network Engineers focus on LAN/WAN and other communication mediums such as mobile networks.
  • Server/Website Administrators maintain and improve on SaaS (Software As A Service) platforms for IoT such as IFTTT.
  • Those online platforms may need a Database Administrator to maintain the backend databases that hold much of the IoT sensor data for example.

Over the years we’ve seen a dramatic decline in the interest in electronics and is fast becoming a dying trade.

This is partly due to the fact that our electronic products are cheaper to replace than to have it fixed by a qualified engineer.


Electronics once had a big following of hobbyists who would build circuits at home for fun and education but the price of components today makes this an expensive hobby.

First came along electronics. Then electronics where used to build computers.


After computers were networked together by using the internet we then seemingly went full-circle and started to use electronic sensors to monitor the real-world and log this data onto servers.

This data can be used to control systems or for research purposes.

Serial Port (RS232)
Parallel Port

Some of you may notice a serial port and/or a parallel port on the back of older PC’s.

These ports were used to connect real-world electronic sensors to monitor our environment.


As time and technology moves on, these busses were rendered obsolete and have generally been replaces with USB.

Raspberry Pi With GPIO Header Pins Highlighted

In 2012 the first Raspberry Pi was introduced into the world and there have been many competitors in the market ever since it’s release.


A Raspberry Pi is known as a single-board computer. It uses ARM architecture similar to mobile devices and is capable of running a desktop operating system similar to a PC.


The Raspberry Pi incorporates GPIO (General Purpose Input Output) header pins directly on to the board.

These header pins can be used to connect various input electronic components such as sensors, and output components such as LED’s (Light Emitting Diodes).


As I mentioned above, the Raspberry Pi is capable of running a ‘fully-fledged’ operating system.

Some projects don’t require as much capabilities as this and so a microcontroller board such as an Arduino can be used.


Arduino’s don’t require as much power as a Raspberry Pi but it can only be programmed with one simple program nicknamed a ‘sketch’.


Again there’s also many competitors to the Arduino on the market as well as many different Arduino’s themselves with different price tags and different capabilities.


Arduino Uno
Arduino Uno

There single-board computers and microcontroller boards are ideal for building IoT devices with whatever sensors we choose to use.

These project boards are relatively cheap to buy, power efficient, have a small form-factor and easily configured by the user.


With all of these factors together we can install our devices almost anywhere.

Using mobile communications such as 4G/5G we can also connect our projects to the internet with ease too. 

I explain Arduino in more detail in my ‘Arduino for beginner’s‘ post.

What Types Of IoT Sensors Are There?

I explained above that IoT sensors are simply electronic sensors.

So “What types of ELECTRONIC sensors are there?” would be a better suited question.

There’s so many electronic sensors that we can use to monitor various types of real-world activity.

IR sensor
Image Shows Infra-red Sensors
Below is a list of sensors that can be used in an IoT application. Please note that this list is not exhaustive and there may be many more not mentioned here:
  • Barometer (air pressure)
  • Microphone (sound)
  • Gyroscope (orientation)
  • Thermistor (temperature)
  • LDR: Light Dependant Resistor (visible light levels)
  • Infra-Red (Infra-red light)
  • RFID: Radio Frequency Identification (proximity radio data transmission)
  • NFC: Near-Field Communication (Similar to RFID)
  • Proximity (close contact)
  • FLIR: Forward Looking Infra-red Radar camera (heat signature radiation)
  • Accelerometer
  • Finger Print Scanner
  • Gravity Sensor
  • Hygrometer (Air humidity)
  • GPS: Global Positioning Satellite System (longitude, latitude, altitude)
  • NFC: Near-Field Communication
  • Orientation
  • Pedometer (movement)
  • Soil Moisture
  • Gas Detector
  • Smoke Detector
  • Pressure

How Do IoT Sensors Work?

IoT sensors/electronic sensors work in many different ways.

For me to explain how each individual component works would require a much more extensive coverage than this blog post.

However I will cover some IoT sensors here to give you a good understanding of how some of these components work.

How An LDR Sensor Works

The above image shows an LDR (Light Dependant Resistor) otherwise known as a photoresistor.

As the name suggests, this component acts as a resistor but the resistance of this component decreases as more light is exposed to the light sensitive material on the top.

Also the opposite is true. As less light falls on the surface of the component then the more resistance it will have.

We can use voltage changes and mathematics across this component to measure it’s state.

This data can be stored electronically and can be further processed if we need.

We can program a computer to switch on a light when a room becomes dark for example.

The relationship between voltage, current and resistance is known as Ohm’s Law and more information on this topic can be found on the wiki.

Ultrasonic Range Sensor
Ultrasonic Range Sensor Module

Many IoT sensors exist as a single component such as the LDR that I previously mentioned above.


Some sensors require some supporting electronic components to function such as an ultrasonic range sensor and so we would see these exist as a module (on a circuit board).

Usually we would purchase these modules ready-made and manufactured.

Reasons for this would include cost, time and reliability.


The ultrasonic range sensor module would emit ultrasonic sound (meaning that humans can’t hear it) and then detect it’s emitted sound reflection.


This sensor module can detect a physical object in front of it at a close proximity such as a wall because the sound waves reflect back from the wall and enter the receiver component.


This module is commonly seen in robotic projects on wheels that would stop it from crashing into walls for example.

What Is IoT Sensor Data?

In the above section I described how the LDR/photoresistor component uses light to physically change the component’s resistance.

We are free to use this data how we please once the local electronic device that holds the LDR stores this data as binary digits in memory.

For example then we can send this data to a central server on the internet where it can be further accessed by other computers.

We could also send this data direct to another device such as our mobile phone.

IoT Sensor Data

How Do IoT Sensors Collect Data?

IoT sensors will store data if we program it to do so. We would usually set a time interval such as every 10 seconds or every minute for example.


Computers work fast and so we would’t usually want a sensor reading every micro-second for example unless it’s purpose required it to do so.


As you can imagine, storing a sensor reading every thousand or even a million times per second would store a vast amount of unnecessary data very quickly.

IoT Collect Data

Depending on what we want the data for would depend on what we would do with the data that has been collected.

If we wanted to trigger a switch on the same device that’s collecting the data then we would store the data in that local device such as a Raspberry Pi or Arduino.


However, we can also transmit this sensor data to a remote location over the internet where we can monitor this data or use it activate a switch on another device somewhere else in the world.

What Are The Most Used Sensor Types In IoT?

We live in a world where almost everyone in the world carries a mobile phone with them.

Today’s mobile smart phones incorporate many different types of sensors such as ones that I’ve already mentioned above.


Components are getting smaller over time and so it makes it possible to fit more of these sensors in to small devices.


Today’s mobile smart phones usually have the following sensors (among others):

  • Temperature
  • Pressure
  • Proximity
  • Accelerometer
  • Gyroscope
  • Light
Mobile Phone IoT Sensors

Technically I wouldn’t say that a camera is an IoT/electronic sensor even though it’s also an input component.


However, camera software can be used in conjunction with a camera to detect movement.

Some camera’s can be used to detect heat signatures too.

A mobile smart phone makes an excellent example of an IoT device.

As you go about your daily life while carrying your phone, you are essentially a walking IoT device.


The sensors inside the phone are sensing real-world data around you and these sensors are storing data more often than we would think.


Phone manufacturers such as Google and Apple and also app developers of your installed apps can pull data from your phone.


Sometimes we allow this data to be taken and other times this data is taken without our consent unfortunately.



In this post I covered the subject of “what are IoT sensors?”


By now you should have a good understanding of how some of these electronic components work individually and how data is stored and processed interactively.


I also covered some of the most common IoT sensor types and briefly described how they work physically.


It’s very possible to build a cheap IoT system and here is more information if you’re interested in trying it at home.

FREE Download: CIoTP Checklist!

The ‘Certified Internet of Things Practitioner’ Certification provided by CertNexus is an excellent blueprint to begin learning IoT.

To download your CIoTP PDF CheckList file Click Here
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Quote Of The Day


"When wireless is perfectly applied, the whole earth will be converted into a huge brain..." - Nikola Tesla, 1926

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