Energy – whether electrical, thermal, or mechanical – can do fantastic things, and sometimes science uncovers phenomena no one even dreamed was possible. Because it’s fun to shock and astound friends and relations with incredible facts, we’re going to investigate some of this unbelievable and really cool information. Our Fun Energy Facts series will be at times hot, cold, weighty, electrifying, and morbid, but we know you’ll get enough of a charge out of it to spark an energetic conversation.
Bending Piezoelectricity to Your Will
Some substances in nature generate electricity just by bending, squeezing, poking, or vibrating them. This is known as the Piezoelectric effect, and it occurs naturally in quartz crystals, metallic ceramics, and biological substances that contain collagen (like your bones). When one of these materials is put under mechanical stress, it acts as a transducer to convert mechanical energy to electrical energy.
Our friends at Nanomotion.com explain it quite succinctly:
One of the unique characteristics of the piezoelectric effect is that it is reversible, meaning that materials exhibiting the direct piezoelectric effect (the generation of electricity when stress is applied) also exhibit the converse piezoelectric effect (the generation of stress when an electric field is applied). … The piezoelectric effect is very useful within many applications that involve the production and detection of sound, generation of high voltages, electronic frequency generation, microbalances, and ultra fine focusing of optical assemblies.
For example, to create a piezoelectric ceramic wafer, you need to remove any charges from all the molecules with positive and negative poles (called dipoles) so you can later realign those charges so they all face one direction. To do this, you heat the ceramic to its Curie temperature – the temperature at which materials lose their permanent magnetic properties. For example, a regular iron magnet will lose its magnetism when heated to 176° F or higher, and heated long enough, it will lose it permanently.
But, if you then surround the ceramic wafer with an electric field, you can induce it to take on a new magnetic field and align its dipoles in one direction (such as all positive poles point up while negative poles point down).
Let’s say you vibrate your brand new piezoelectric ceramic wafer using your voice (this is how a basic microphone works). This causes the charge density in different areas of the material to change: positive charges rise at one end and negative charge rise at the other. POOF —you’ve got an electric circuit.
And with some of these materials, you can use electricity to deform your piezoelectric creation so it causes a mechanical effect. That’s what happens in inkjet printer heads and piezo tweeters for audio speakers.
So, What Cool Stuff Can You Do with a Piezoelectric Transducer?
The short answer? Something we’ll call “energy harvesting.”
Piezoelectric transducers lets you collect energy from practically everything that moves or vibrates. That includes dance floors, roadways, and powering medical implants with flexible bio-piezoelectric nanogenerators made from waste fish scales. In fact, California just approved a pilot study to generate power through roadway embedded piezoelectric crystals.
And there are several gadgets you and your kids can create with them, too.
One of my faves is an electric guitar bridge with piezoelectric crystal pickups built into the string guides. These pull vibrations straight from the string to put out a clean acoustic-type guitar sound — even if it’s a guitar made from a concrete block.
What other creative applications of science would you like to learn about in future installments of Fun Energy Facts? Share with us in the comments!