Can a Piezo Crystal be Used as a Segmented Actuator for Voltage Measurements?

In summary, piezo crystals can produce a voltage when pressure is applied and can deform when a voltage is applied. There is the possibility of applying pressure to only a small region of the crystal and getting a voltage measurement from that specific area. This concept is used in segmented piezo actuators, which involve a single crystal plate with multiple segmented electrodes. Some examples of this design have been demonstrated by Binning and Smith in 1986 and have been successfully replicated by amateurs using cheap piezo buzzers. This technology has also been used in the creation of a homemade scanning tunnelling microscope.
  • #1
Sturk200
168
17
I think I understand the basics of piezo crystals. You apply pressure and the crystal produces a voltage. Conversely, you apply a voltage across the crystal and it deforms.

My question is this: if you were to apply pressure to only a small region of the crystal (if that's possible?), would the voltage be produced only across that region, or would it spread throughout the crystal? What I'm getting at is the idea of hooking up a number of leads to to the surface of a crystal and getting distinct voltage measurements from different physical regions of the object. Is this a thing that happens?

Thanks.
 
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  • #2
I guess so. This is used the other way around (apply voltage and get movement) to make some neat little piezo actuators. Google "segmented piezo actuator."
 
  • #3
Daz said:
I guess so. This is used the other way around (apply voltage and get movement) to make some neat little piezo actuators. Google "segmented piezo actuator."

Thanks, I just ran a search. I can't tell if "segmented actuator" means they have a number of distinct crystal plates somehow formed into a "segmented" array, or if they are literally taking a single crystal plate and extracting from it information about localized stress/strain. The latter is what I was thinking of. Do you know of any examples of that being successful?
 
  • #4
Sturk200 said:
I can't tell if "segmented actuator" means they have a number of distinct crystal plates somehow formed into a "segmented" array, or if they are literally taking a single crystal plate and extracting from it information about localized stress/strain.
This page may be useful. http://www.piezo.com/tech2intropiezotrans.html
 
  • #5
Sturk200 said:
I can't tell if "segmented actuator" means they have a number of distinct crystal plates somehow formed into a "segmented" array...

What I have seen consists of a single tubular piezo element with multiple segmented electrodes around the outside. This design was first demonstrated by Binning and Smith in 1986 (Rev. Sci. Instrum. 57(8), p. 1688, 1986.) I don't know if that's how the commercial ones work but I expect at least some do.

In any event, some enterprising amateurs have even made their own from cheap piezo buzzers. Here's a fascinating little project by someone who made his own STM (scanning tunnelling microscope) using parts from hobby electronics stores.

http://dberard.com/home-built-stm/scan-head/

Check out the fourth photo.
 

1. What is a piezo crystal?

A piezo crystal is a type of crystal that generates an electric charge when pressure or mechanical stress is applied to it. It is made up of a material, such as quartz or ceramics, that has the ability to convert mechanical energy into electrical energy.

2. How does a piezo crystal work?

When a piezo crystal is subjected to mechanical stress, the crystal structure deforms, causing a displacement of positive and negative charges within the crystal. This displacement creates a voltage difference between the two surfaces of the crystal, generating an electric charge.

3. What are the applications of piezo crystals?

Piezo crystals have a wide range of applications, including in sensors, actuators, and transducers. They are commonly used in medical imaging devices, such as ultrasound machines, as well as in electronic musical instruments, pressure sensors, and precision positioning systems.

4. How are piezo crystals made?

Piezo crystals are typically made by cutting a piece of material, such as quartz or ceramics, into a specific shape and size. The crystal is then polarized by applying an electric field to align the positive and negative charges in the crystal. This process creates a piezoelectric effect, making the crystal capable of producing an electric charge.

5. Can piezo crystals be used in both directions?

Yes, piezo crystals can be used in both directions. When an electric charge is applied to the crystal, it can generate a mechanical displacement, and when mechanical stress is applied, it can produce an electric charge. This bi-directional capability makes piezo crystals versatile and useful in various applications.

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