Piezoelectricity
A technology of the past and future…
The reason why I say it's a technology of the past and future is because of how unbelievable and how old it is. Imagine a device that creates electricity by just squeezing it. Sounds wild right! I mean this could solve the energy crisis and even climate change. Now, what if I told you that a technology like this existed 150 years ago! In March 1880, the Curie brothers (Paul-Jacques Curie and Pierre Curie) discovered piezoelectricity.
How it works
There are 4 main components in a piezoelectric disk.
- Metal disk on top
- Piezoelectric material in between
- Metal disk at the bottom
- 2 wires connecting to the bottom and top metal plate (these wires will be connected to the device u want to power)
The most important part is the piezoelectric material in the middle. Only piezoelectric materials can be used for the middle part because of their molecular structure. When compressed, positive charges collect at the top and negative charges collect at the bottom. Thanks to the metal plates, we can harness this charge as AC electricity through the wires. The best piezoelectric material used in piezoelectric disks right now is called PZT or lead zirconate titanate.
To better explain this picture better, this is the molecular structure of the piezoelectric material quartz. On the left is the molecular structure when no external force is applied. Now on the right is when it is compressed or squeezed. As you can see, negative charges collect at the bottom, and positive at the top. Yellow is silicon and red is oxygen. Now the reason quartz is piezoelectric is because of a lack of symmetry with its molecular structure. If u were to draw a straight line from any atom to the atom opposite it. You will see that it is another type of atom. If you draw a straight line from the oxygen atom to its opposite atom, it is a silicon atom.
As you can see in this photo, as force/compression is applied, the net charge remains neutral and produces no current.
The truth…
After reading about piezoelectricity you may be thinking, “this technology is so cool and we can run the world with this- wait, why haven’t we?” The truth about this technology is that it isn't efficient for large scale ideas like running towns with this. The piezoelectric material isn't as efficient for this. Yet, piezoelectricity is great for small devices! Small deices meaning lighters, those birthday cards that sing, etc. If we could invent/discover a new type of piezoelectric crystal, we could revolutionize energy generation. The problem is that we have already invested time and money and the best one we could find was PZT or lead zirconate titanate. So we decided to go with some simple applications for piezoelectricity.
Applications
There is a ton of simple applications of piezoelectricity like birthday cake lighter, sound playing cards or teddy bear, printers, watches, production and detection of sound, etc. All of these things run on piezoelectricity.
Lighters
Ever wondered why lighters take a significant and repetitive amount of force to light? It’s because you are actually hitting a piezoelectric element that sends a small spark to where the flammable gas is released. When the spark hits the gas…boom, a flame appears!
Sound playing items
Sound playing item such as a birthday card or teddy bear use piezoelectricity to play that musical sound. When u squeeze the teddy bear’s stomach, you are actually squeezing a piezoelectric material that sends electricity to play the sound. The same thing in birthday cards, when you open the card, a sound plays! Piezoelectric disks are pretty thin so that's how they fit between the card flaps.
As you have read, you can get electricity by compressing a piezoelectric material. The same is applicable vise versa and is called the reverse piezoelectric effect…
Reverse piezoelectric affect
The reverse piezoelectric is where, as you have read, an electrical current is induced in a piezoelectric material which causes it to change its shape. This change isn't large and is actually is a pretty small change in shape.
The main use for this is in actuators. An actuator is like a mechanism. So when an electrical current is induced into this piezoelectric material, it changes shape which can lead to a chain reaction to make something happen. This is used in quartz watches.
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Something that still confuses me is why were are using such an insane and useful technology for such simple and non-environmental-impacting devices. I know that I said that piezoelectricity is great for small devices but the fact that we are only using it for electronics that have little to no non-environmental impacting surprises me. There a lot of electronics that have huge environmental impacts that could be fully run by piezoelectricity because we need to press/tap it to use it like phones. Not only that but most people are using the reverse piezoelectric effect which uses electricity instead of creating it.
The best solution for this is to discover a new type of piezoelectric material. the last time we tried this was a couple of decades ago. With the way we have advanced, I know that we can find a better and efficient piezoelectric material if we put the time and money into it. Right now this seems risky and not a short term plan to stop climate change in its tracks. What I believe we can do is find better applications of piezoelectricity. Electronics with high energy consumption could be fully run on piezoelectricity because to use them, you need to use some mechanical stress like with a phone, you tap the screen. Mechanical stress is abundant as we produce it every second of our lives.
What this means for the future
We could fully run everyday electronics on piezoelectricity. This could be applied in every industry from health care, to industrial, I know that piezoelectricity will bring the world closer to run fully on clean energy.
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Quick re-cap
- Who discovered piezoelectricity
Piezoelectricity was discovered by the Curie brothers in March 1880
- How does piezoelectricity work
When you apply a force or pressure to a piezoelectric material, it generates a current due to its molecular structure. When compressed, negative charges collect at the bottom and positive at the top. This can then be harnesed as DC power.
- The truth
Piezoelectricity isn't efficient enough for large scale projects but is excellent for small ones.
- Applications
Piezoelectricity is used in our daily life without you knowing it. It is used in lighters, musical birthday cards and teddy bears, printers, watches, and the production.detection of sound
- Reverse piezoelectric effect
The reverse piezoelectricity effect is where an electrical current is induced into a piezoelectric material, which causes the piezoelectric material to deform and very slightly change form.
- The future of piezoelectricity
Piezoelectricity has great potential but we just have to give it a 2nd look.
- What this means for the future
We could run everyday electronics fully with piezoelectricity. This technology could be applied in every industry out there. I believe this technology will take us closer to running on only clean energy.
