Piezo material is a crystalline substance which has the property of generating electricity when its crystalline structure is subjected to a certain mechanical stress level.
Conversely when the same crystalline structure is subjected to an electric current it exhibits an equivalent level of deformation which in turn causes a sound to be generated.
That's exactly why piezo elements are used in buzzers for generating sound by applying an pulsating voltage across it.
Therefore we can conclude that the discussed property of piezo material is flexible and reversible, meaning it allows both, generation of electricity when deformed, and generation of sound when electrified.
Having said this, care must be observed not to over limit the stress level on a piezo while attempting to generate electricity from it since the deformation limit of a piezo element is
extremely small, exceeding which could result in breakage or permanent
damage of the element.
For experimenting the generation of electricity from a piezo, the easiest way to access a piezo material is to procure the standard 27mm piezo element which are normally used in piezo buzzer circuits.
The picture below depicts a couple 27mm piezo elements which may be readily available in most electronic spare part stores.
The right side pic shows a 2-pin piezo element, while the other one represents a 3-wire, any of these will work for the experiment.
Once the piezo is procured, solder a couple of wires to it, connect a 20mA white LED across the other end of the piezo.
As soon as the above assembly is built, you can make the LED illuminate brightly momentarily by flicking the edge of the piezo with your finger.
Each time you strike the piezo with your finger, you can find the LED illuminating brightly during that instant.
And somehow if the striking is sustained through some external means, would enable the LED to illuminate rapidly, or even continuously if a capacitor is connected across its leads.
If the output across the piezo wires is measured, you would be surprised to see the voltage to be as high as upto 5V depending on how hard the striking was.
While conducting the above experiment make sure the piezo is pinched tightly from opposite edge with your other hand fingers, do not clamp through any mechanical tool as that could crack the piezo causing permanent damage to the element
Fancy Carom Board Using piezo Lit LEDs
The above explained concept of generating electricity from piezo transducer and illuminating an LED could be implemented in carom boards, for producing attractive LED illumination within the coins and also around the inner surfaces of the board rim.
SMD LEDs could be used for flush embedding them within the carom coins surface such that they do not affect the sliding effect of the coins.
The inner edges of the board could be also embedded with piezo/LED assemblies for generating the proposed piezo electric LED illumination.
Once this is done, each time the coins are struck or when coins hit the board edges the associated LEDs could be expected to light up brightly for that second producing interesting LED light show.
Using piezo electricity in Children Shoes.
The effect of piezo electricity could also be effectively used in children shoes, by suitably fixing the piezo, LED assembly beneath the heels of the shoes. This would enable the LeDs to light up brightly each time a step is taken by the child wearing these enhanced shoes.
Many more such innovative ideas could be implemented by using the proposed concept of generating electricity from a piezo buzzer element, if you think you have even more interesting ideas do let us know about it through your comments.