What exactly are sensors? What do they do and how do they help? Well, sensors are objects which detect events or changes in its environment. It sends this information to the computer and then tells the output device to provide the corresponding output. In other words, it changes real world data into information to be used elsewhere. As for specifics, you’d have to look at specific sensors because each one does something different. There are:
Machine Vision/Optical Light Sensors — These tend to be cameras of some sort or another and can be used for anything from detecting edges to light levels to geographical locations. Think of 3D printers for this one or even just your webcam.
Position/Presence/Proximity Sensors — They’re able to detect nearby objects without any physical contact. They’re good for systems where you might need to avoid colliding with things you can’t see or, in the future technology arena, 3D screens.
Motion/Velocity/Displacement Sensors — These work in a similar fashion to proximity sensors, but instead of focusing on whether something is close, it focuses on how quickly it’s getting closer or farther away. These are used in anything from radar guns that police use to security systems.
Temperature Sensors — Temperature sensors are pretty straightforward. They measure the temperature around them and relay that information. Think thermometer.
Humidity/Moisture Sensors — Another straightforward type of sensor, they measure the amount of water something has in it. These can be used in many agricultural projects from soil to air, or can be used in more industrialised places to determine and other problems.
Acoustic/Sound/Vibration Sensors — These work very similarly to the above motion and proximity sensors, but instead of focusing on objects, they focus on the level to which something vibrates, vibrations per second (loudness and pitch) and can be used to create images of something based on these vibrations. These can be used in ultrasounds or, well, ears.
Chemical/Gas Sensors — Gas and Chemical sensors can measure concentrations of various chemicals and gasses. They’re best used anywhere using dangerous chemicals, including carbon monoxide sensors or anything else.
Flow Sensors — These determine the flow rate of water, air, or any other liquids or gasses that might flow. They’re great for engines, water conservation systems, and anything else with delicate systems focusing on conservation or efficiency.
Force/Load/Torque/Strain/Pressure Sensors — These sensors tend to measure compression and tension. They can be used very effectively in systems with rotating parts like an engine, motor, or turbine, and are commonly found in hand tools as well.
Leak/Level Sensors — Another very straightforward type of sensor. These find leaks in systems from any number of means whether it be floats or electrosonic level transmitters. To be frank, they’re used to determine whether there is a leak somewhere.
Electric/Magnetic Sensors — These sensors are different from most in that they determine changes in the magnetic or electrical field that has been created or modified and from that, determines direction, presence, rotation, and other variables. They can be used in various applications from traffic control signals to security-devices used by the military.
Acceleration/Tilt Sensors — These are used to help determine direction and speed. They can be used in things that need to move around in the physical world like robots or cars.
As you can see, there is a huge amount of variation in sensors that you might not have even realised. In the same way that a car doesn’t need arms, a lot of devices don’t need a lot of these sensors because, frankly, some information is just useless. My coffee maker doesn’t need to know how fast I’m approaching it, but it absolutely needs to be able to determine the temperature of the liquid, whether it’s running out of water or even leaking.
Determining what sensor each device needs is crucial to obtaining efficient and cost-effective products. In the Internet of Things, that’s no different, so before you start grabbing up every sensor known to man, do a little research and figure out just what it is you’ll need.