We are looking into Internet of Things and are learning a few things about it. Hope you are excited and are ready to move along. If this is the first time you are visiting this blog, I request you to go through the earlier posts to get some basic understanding of this topic. Today, we will take a look on the various sensors in IOT


Sensors are devices that can be used to record, collect or act upon a physical property. Heat sensors can measure heat, pressure sensors measure pressure and so on…On a high level, these sensors can be classified as follows

Temperature – Used to measure temperature related data. A few examples are Thermistors, thermocouples, RTD, Thermophile infrared sensors. If you want to measure the temperature of your room or the weather in general, you would be looking at one of these sensors

Pressure – Thermistors, thermocouples, RTD’s, IC and many more. These are used to measure the pressure of liquids or gases. This can be used to measure atmospheric pressure, liquid/gas escape pressure in machinery etc

Flow – Electromagnetic, differential pressure, positional displacement, thermal mass. These sensors are used to measure the rate of fluid flow. This can be used for water level indication, measuring rate of water flow etc

Level sensors – Differential pressure, ultrasonic radio frequency, radar, thermal displacement

Proximity and displacement – LVDT, photoelectric, capacitive, magnetic, ultrasonic. These are used to calculate distance between two targets.

Biosensors – Resonant mirror, electrochemical, surface Plasmon resonance, Light addressable potentio-metric. These can be used to detect the presence of chemicals in food products.

Image – Charge coupled devices (CCD), CMOS are basic image sensors.

Gas and chemical – Semiconductor, Infrared, Conductance, Electrochemical. These can be used to detect types of gases and chemicals

Acceleration – Gyroscopes,  Accelerometers. These are found in your mobile phones and is used to track movement. Have you seen apps that measure the steps that you walked each day? It is accomplished through accelerometers and gyroscopes.

Others – Moisture, humidity sensor, Speed sensor, mass, Tilt sensor, force, viscosity

You may be wondering if I have drifted off too much into electronics, but having a basic knowledge on these sensors is very important to understand the big picture of IOT. Suppose, you get a requirement to monitor the temperature and pressure levels in a particular locality spanning 2 km radius. How would you go about designing such a system?

Obviously, you will pick the temperature and pressure sensors, fix them in a moving or static target. If it is a static target, you will fix it in more than one place. These sensors will then be connected to an electronic circuit (device) which will be connected to the internet through a communication mechanism as we had seen in the earlier post.

As an exercise, I would suggest you to come up with various real life use cases and map these sensors on how they can be used to come up with tracking and monitoring systems.


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