In the world of computing devices like Arduino, Raspberry Pi, Teensy, and BeagleBoard, there are a wide variety of applications where you may need some sort of vibration sensor. Perhaps your project detects when the laundry is done, or monitors industrial motors for predictive maintenance...or maybe you need to know if your robot falls down the stairs.
One solution is to use an inertial measurement unit (IMU), as outlined here. However, if that’s overkill and you just need to know that something is shaking, one of these simple vibration sensors could be perfect.
Capacitive vibration sensors: slow/medium/fast vibration switch
For a simple and inexpensive vibration sensor solution, this series of vibration switches could fill the bill quite nicely. Resembling a small electrolytic capacitor, these devices use a coiled spring as one of the contacts. When sufficiently shaken, the top of the coil hits the other relatively static contact. The Fast (1766) variation is easy to trigger, slow (1767) is hard to trigger, and medium (2384)—as you’ve probably guessed—takes a medium amount of vibration to activate.
Simply hook one lead up to an input, and the other to ground/VCC, as required. This type of sensor needs no power to stay vigilant, and could be a great way to wake a process up from sleep mode. Note that in testing, I was able to get the fast and medium sensors to trigger with a 12V vibrating motor, but not the slow sensor. This type of sensor apparently requires quite a smack for activation, so it might be wise to buy all three for testing, or start with medium and go up or down.
Piezo vibration sensor circuit
If you need a bit more refinement, at the expense of a more complicated setup and higher cost (listed as of this writing at $6.51 vs about a dollar for each of the three switches listed earlier) this piezo film vibration sensor and board may fit the bill. It consists of a piezo film, which hooks into a module that outputs to the microcontroller of your choice.
While there is only one output pin, the board contains a slider switch to choose whether it produces a digital or analog signal. An adjustment potentiometer is used to adjust the output set point in digital mode, and its documentation claims a measurement range of between 0.001 Hz and 1000MHz. As tested, reading the analog output over serial, the device was easy to set up, and could be an appropriate solution in many applications.
Digital vibration sensor
For something in between these two modules, complication and cost-wise ($2.10 as of this writing), the SW-420 Vibration Sensor Grove Board is another interesting option. It features only a potentiometer-adjustable digital output, which normally reads high, and goes low when triggered. The sensor itself audibly shakes when moved back and forth, per a roller inside the sensor unit. It can be powered by either 3.3V or 5V, and can be used to detect a tilt as well as vibration.
Vibration sensor types: many options for your project
While an IMU is appropriate at times, don't forget to consider what information your project actually needs, and what data can be safely neglected. What's presented here gives you a variety of sensing options, useable in many situations!
