What Is a Piezo Element?
A piezo element is a piezoelectric component that changes shape when voltage is applied to it and, conversely, produces voltage under pressure/vibration.
The Piezoelectric Effect
Certain crystal/ceramic materials show a two-way property: they vibrate mechanically when given electricity (actuator), and they produce electricity when subjected to mechanical pressure (sensor). This two-way behavior makes the piezo element versatile.
| Direction | Function |
|---|---|
| Electricity → motion | Produces sound/vibration |
| Motion → electricity | Senses pressure/vibration |
Producing Sound
When a frequency signal is applied to a piezo element, it vibrates rapidly and makes sound. A piezo buzzer uses exactly this; it's thin and efficient and good at high tones.
As a Sensor
Conversely, an impact or vibration produces voltage from the piezo element. This is used in knock/impact sensors, drum triggers and vibration detection.
Where Is It Used?
Piezo buzzers, alarms, vibration/impact sensors, ultrasonic transmitters, lighter igniters and precise positioners.
Driving and Capacitive Behavior
A piezo element is electrically similar to a capacitor (a capacitive load). So it's driven not by DC but by a varying signal; the driver circuit must account for this capacitive load.
Common Mistakes
- Driving with DC: a piezo needs a varying signal for sound; steady DC makes no sound.
- Capacitive load: not choosing the driver for the capacitive behavior.
- High voltage: the voltage spikes it produces can stress a measurement input.
Frequently Asked Questions
Is a piezo both a speaker and a sensor?+
What's the difference between a piezo buzzer and a piezo element?+
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