11 Surprising Things Piezoelectric Crystals are Used in

You might be surprised how many household items piezoelectric crystals are used in. Some of these piezoelectric crystal examples are actually INSIDE your body, others you may use on a daily basis. Here is a list of the 11 most common household items piezoelectric crystals are used in.

1. Piezoelectric crystals are used in …Lighters

Probably the best demonstration of how piezoelectric crystals work is a common lighter. When you flick the wheel, you strike the piezoelectric crystal in the metal cap. That strike puts pressure on the crystal inside, causing an electric current to run through it. After the flick, the crystal has electricity in it. When an electric current doesn’t have anywhere to go, like into a wire, the energized electrons leak out and cause HEAT. This heat and internal friction is what causes the spark and the fire.

2. Analog Watches

Digital watches keep time with a miniature computer inside, but analog watches use a quartz crystal. Here you can find the intriguing history leading to quartz watches. With a combination of a small battery providing current to the quartz, there are electrical impulses on the surface of the quartz, vibrating it with precision. The battery also reads the vibrations.

3. Microphones

Microphones are one of the best examples for understanding how the piezoelectric effect works. Microphones have detectors that vibrate under pressure from sound. The piezoelectric crystal components basically read that out to produce the electric current corresponding to the sound (that the speaker component will read). Read more about how microphones work.

4. Piezoelectric crystals are used in… The inner ear

Your inner ear listens and takes in sound like a microphone does. The tiny hairs on the inside of your ear vibrate and that signal passes on to the brain. The piezoelectric crystals used in hearing are in the cochlea, and research on how exactly they vibe drives forward the development of hearing aids. These crystals, called otoconia, are mainly calcium carbonate, the same material as eggshells. We can also process signals via “electrophonic hearing,” the brains tricky way of hearing without sound.

5. Hair Straighteners

Most hair straighteners are tourmaline-coated. Tourmaline coated hair straighteners avoid static electricity from frizzing up your hair during the straightening process, which would normally put too many extra electrons on your hair, making them repel each other (see: rubbing a balloon on your head). When those electrons leave your hair shaft, there are positive charges on the hair which are basically free radicals causing damage over time. Tourmaline coated hair tools emit negative ions to bind with those free radicals leaving the hair silky.

6. Non-stick Cookware

Some non-stick cookware uses tourmaline, the same ceramic-structured coating as hair straighteners. Companies try to make the least toxic and most effective non-stick coating for cooking. Novel configurations of piezoelectric crystals are used for this. Those engineering coatings deposit with small bumps on the surface, the size of mater molecules (you cant see these bumps). Because most particles can’t sink into the surface, it stays on top giving the non-stick effect. As far as I know piezoelectric crystals are used in non-stick cookware, but not exactly to exploit the piezoelectric effect.

7. Sugar

Now, this isn’t so much that “piezoelectric crystals are used in” sugar, but that sugar naturally exhibits the piezoelectric effect. The molecular structure of sugar is crystalline, which is why sugar-based candies can look like glossy crystals. Sugar comes in many different molecules, the simplest being glucose, C₆H₁₂O₆. In a clump, or a grain of sugar the 6-membered carbon rings are varying degrees of offset. When mechanical forces push the planes of sugar, the piezoelectric effect takes place and electricity actually conducts in the sugar. This is why the ‘ole “chew up Wintergreen Lifesavers in a dark room” experiment works. (If you haven’t tried it, it results in sparks flying out of your mouth!) The extent of the piezoelectric effect in candy depends on how its made, and depends on how it sets when it’s cooling. Interesting to think of dissolved crystals in your bloodstream!

8. The Pineal Gland

The pineal gland is what makes melatonin (out of serotonin). The gland is the the center of your brain and is the size of a blueberry. The piezoelectric crystals used in the pineal gland are specifically calcite crystals, which also exist naturally in some rocks. A form of calcite even makes up eggshells. The pineal gland has a super cool Fibonacci spiral structure resembling a tiny pinecone (hence the name) where the shingles are the piezoelectric calcite crystals. Now these piezoelectric crystals are used more often with the “inverse piezoelectric effect”. They take in with ULTRA SENSITIVITY electromagnetic signals which causes physical deformations. These deformations allow the pineal gland to do its job and create hormones.

9. Your Bones

Of all the “body parts” in this post, bones are probably the best at exhibiting the piezoelectric effect. The same material makes up teeth. Bones are made of collagen, so yes, piezoelectric crystals are used in any [art of the body that has collagen. The effect is very pronounced to bone to the point where it likely serves some evolutionary advantage. When a bone receives pressure, the resulting current tells the body to strengthen that bone if it can. Researchers are finding that they can regenerate bone to some extent exploiting this effect.

10. Piezoelectric crystals are used in… Seatbelt Sensors

Don’t you love when your modern-era car beeps at you relentlessly to put on your seatbelt? How does it know? These mechanisms usually work through a piezoelectric sensor in the seat cushion. When a person is sitting it puts the mechanical pressure on the sensor. The piezoelectric sensor then deforms to allow electric current to pass through, completing the “beeping” circuit.

11. and finally, Piezoelectric crystals are used in… Ceramics

This is a whole class of materials and the ceramic items in your home may or may not have piezoelectric characteristics that you would be capable of producing. For example, in a quartz crystal, not ALL electric currents will cause a deformation. An electric current has only a certain amount of energy carried with it, and the energy of the current must be “tuned” with the material to see the effect. But most ceramics have matrices (structured blending of different compounds) of molecules that make up the class of piezoelectric crystals scientists study to find new ceramic coatings.

It’s incredible how many more things piezoelectric crystals are used in outside this list of 11. Learn more about how energy travels in crystals.