Electricity from Piezoelectric materials

Easy experiment that shows how to get electricity from Piezoelectric materials, a clean source of electricity. Also, some interesting applications. (11/13/2008)


The "piezoelectric" effect was discovered about 1880 by Jacques & Pierre (The Curie brothers). They found out that when a mechanical stress was applied on crystals such as tourmaline, topaz, quartz, Rochelle salt and cane sugar, - YES! cane sugar! - electrical charges appeared, and this voltage was proportional to the stress. That means, more force = more electricity. How much electricity??? let's find it!


Piezoelectric from a Watch clock To make a simple experiment, we need to get a piezoelectric. As sugar cane breaks easily and can be a little messy, we can get the piezoelectric speaker from a broken watch clock. Any alarm watch clock can be used.


Connecting a LED I did connect a BLUE LED using solder, but tape will work also. Just apply some tape connecting each LED leads to the white side and the opposite of the piezoelectric speaker.


Now, using a pen, pencil or marker, tap the piezoelectric surface and the LED will lit.


LED lits Blue LED lits


Using the mousepad helps to keep the piezoelectric intact and it doesn't break easily. Tapping the piezo speaker, I got about 6 Volts and 120 mA. The electricity from the piezoelectric is AC, so it can be converted to DC using a bridge diode.


Some applications for this interesting effects are:


  • Quartz Clocks - Piezoelectric materials resonates when electricity is applied and generates a pulse of certain frequency.
  • Airbag Sensor - When any object hits the airbag sensor on a car, it sends a pulse that triggers the explosion in the Airbag.
  • Lighter - The gas from a lighter is ignited by a spark generated by the piezoelectric.

    The piezoelectric effect occurs only in non conductive materials and are divided in 2 main groups: crystals and ceramics. The most well known material is quartz (SiO2) as this easily available. A simple way to generate electricity is using a Rijke Tube.


    Do you know any other application for piezoelectric materials?


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