When youre planning an Internet of Things or machine-to-machine communications deployment, how your system gathers data is crucial to the projects success. Understanding the IoT/M2M sensors and selecting the right sensors for the task can make or break your business. Thats why Aeris eBook, The Definitive Guide to IoT for Business, devotes a whole chapter to IoT sensors and data collection. Especially if youre not an engineer or data scientist, this book can provide an overview of the more common sensors used for IoT/M2M applications, how they function, and how to use them to get the best results.
Types of Sensors Used to Measure IoT/M2M Data
Sensors are often integrated circuits designed specifically for IoT/M2M applications, since the small size and low cost of these chips make them appropriate choices. For example, many of the sensors used for IoT/M2M are available in high-end smartphones. These include accelerometers, thermometers, gyroscopes, magnetometers, and heart-rate monitorsjust to name a fewbut there are other sensors that are unique to a particular industry or market.
Measuring changes in speed or direction with accelerometers is very useful, and similarly multi-axis accelerometers add in motion changes and vibration in three dimensions. For example, a shock sensor designed to release a vehicle airbag in an accident measures quite a different range compared to a sensor that measures vibration on a high-speed motor to monitor its bearings. The sensitivity and accuracy required for these widely disparate applications is naturally quite different.
Temperature is very commonly measured by IoT/M2M applications, and this can be achieved in a variety of ways, depending on the application, sensitivity needed, and cost. Silicon chip (semiconductor) sensors are quite accurate without the need for extensive calibration. They are also as rugged and relatively inexpensive. Thermistor sensors can cover a wider temperature range, and theyre more accurate, but at a slightly higher cost per sensor. Thermistor sensors do require a complex correction to achieve good accuracy over the desired temperature range.
Resistance-Temperature Detectors provide yet more range, but theyre the most fragile of these sensors. Yet they can be a hundred times more accurate than a silicon chip sensor, and for the widest temperature range, especially at high temperatures, a thermocouple is a good choice. Theyre rugged and can be used in many industrial applications.
A broad range of IoT/M2M applications use light sensors for with sensitivity ranging from simple proximity detection to full light measurement equivalent to human vision. Common uses of light sensors include control of street lighting systems, motion-controlled alarm systems, and even medical diagnostic equipment.
Another popular type of sensor is found in IoT/M2M devices and in high-end smartphones. These integrated chip sensors are called Micro-Electro-Mechanical Systems (MEMS) sensors, and theyre used to measure motion, direction, pressure, magnetic fields, etc. These can be used to correct for hand-held shake in video and still-image cameras and human motion sensing for video games. In smartphone applications, a screen display can be automatically rotated from portrait to landscape display modes when the phone is physically rotated.
Even simple, open/closed state switch sensors are useful in IoT/M2M deployments. A door or window sensor used in security systems is often a simple magnetic reed relay switch that opens or closes an electrical circuit depending on the position of a small magnet relative to the switch. These simple switches can also be used for sensing when a medicine cabinet, oven door, or food storage compartment has been opened in a senior citizens home-monitoring IoT application.
Find out more about planning your IoT/M2M project with The Definitive Guide to IoT for Business.