Question on use of Piezoelectric sensor:

In summary: Thanks for the help!In summary, you can use piezoelectric sensors to measure low-frequency vibrations. You need to determine how the sensors will be interfaced and other details.
  • #1
H_man
145
0
Hi,

I am aware that in the traditional sense Piezoelectric crystals/ceramics cannot be used to measure static/steady state forces.

However, I was wondering how low their frequency response can go.

That is, is it possible to measure a force of maximum strength 1mN that will develop from zero slowly (over a period of about 0.5-1second) to maximum strength and then dissipate over the same period.

I am worried that my signal will get lost due to the (of course) non-infinite impedance of voltage measuring equipment.

Is my fear justified? Can such a "slowly" varying force be measured?

This is my first foray into the world of such sensitive measurements and any help or suggestions would be appreciated.

Thanks.
 
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  • #2
If I recall correctly, you can go down to around 10Hz with PZT. Anything slower than that you'll have to worry about bleedoff.

Is there any reason a simple strain gage would not work for your application?
 
  • #3
Thanks Enigma,

Yup, I can´t use a strain gauge as I am measuring the impulse from a plasma plume. The high temperatures would kill the gauge very quickly.

I stopped thinking about PZTs some weeks ago as I didn´t think they would work due to the long build-up time of the pulses(even though there are devices I found than can withstand temp. of up to 1100K).

I have other ideas but my supervisor (who is a theoretician) was quite insistent that I use a PZT and I was quite insistent that it wouldn´t work.

:frown: There will have to be another tense meeting...
 
  • #4
Is there perhaps some way that it can be done optically or accoustically? I don't know anything about it; just throwing out a thought. Something perhaps like having a standing air mass of known properties in the plume path, with a funnel or tube leading to a transducer to measure the pressure increase.
 
  • #5
Thanks for the suggestion Danger, but unforunately that's not possible as the plume is being generated in a vacuum (you also have to consider the incredibly high temp. of the plasma).

I think I have found the solution in some electronics to control the period of the plasma pulses (and so use the PZT s but just at a much higher freq.).

But originally I just wanted to make sure that I wasn't wrong about the PZTs poor response at low frequencies... as I have another meeting tomorrow.

:approve:
 
  • #6
Yeah, I guess that introducing an air mass would to some small degree compromise the integrity of your vacuum. :biggrin:
I didn't know that the pulse frequency could be adjusted. It seems that you've found a good solution. Good luck at the meeting. Keep us posted.
 
  • #7
H_man said:
Thanks Enigma,

Yup, I can´t use a strain gauge as I am measuring the impulse from a plasma plume. The high temperatures would kill the gauge very quickly.

I stopped thinking about PZTs some weeks ago as I didn´t think they would work due to the long build-up time of the pulses(even though there are devices I found than can withstand temp. of up to 1100K).

IIRC, the high temperatures will depole the crystals pretty quickly. I'm actually kind of surprised that they're advertising 1100K.

Are there any magnetic properties of the plume you could utilize?

Could you draw a quick sketch of the proposed experimental setup?
 
  • #8
The K-12 material in the table on their website is listed for applications up to around 1000K.

http://www.piezotechnologies.com/materialssheet.htm [Broken]

I was pretty surprised myself

I have the data sheet for the material which does show how properties vary with temp. Although, unforunately it doesn't show the effect of repeated heating and cooling cycles.

My gut feeling is that if I am to use the PZT its going to have to be contained within some kind of cooling jacket, perhaps with water (in a sealed pipe) helping draw the heat away. Also... I won't be letting the plasma directly impinge on the crystal.

As for how the setup is going to look... I am fairly free to orientate things as I wish. As for hows its going to look :rofl: , your guess is as good as mine.

As for magnetic properties of the plume... this wouldn't help an impulse measurement.

I'll keep you informed...:smile:
 
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  • #9
hi,
can I use peizoelectric sensors to obtain and record the low substrat vibrations? if ı use, how can ı do?
thanks in advance
 
  • #10
I'v ever one time saw one introducing article on the peizo sensors application from one web . It has a quite detailed data sheet on it ...Hv to recall the memory ...seems frequency decided the sense like that .
 
  • #11
nivalis said:
hi,
can I use peizoelectric sensors to obtain and record the low substrat vibrations? if ı use, how can ı do?
thanks in advance



YES . OFX U CAN . It is up the sensors u chose.
 

1. What is a piezoelectric sensor?

A piezoelectric sensor is a type of sensor that converts mechanical energy (such as pressure or vibration) into an electrical signal. This is achieved through the use of piezoelectric materials, which generate a voltage when subjected to mechanical stress.

2. How does a piezoelectric sensor work?

A piezoelectric sensor works by utilizing the piezoelectric effect, where certain materials generate an electric charge when subjected to mechanical stress. The sensor consists of a piezoelectric material sandwiched between two electrodes. When pressure or vibration is applied to the material, it generates an electrical charge that is measured by the electrodes.

3. What are the applications of piezoelectric sensors?

Piezoelectric sensors have a wide range of applications, including but not limited to: measurement of force, pressure, acceleration, strain, and vibration; in medical devices for monitoring vital signs; in automotive and aerospace industries for engine and structural health monitoring; and in musical instruments and audio equipment for sound amplification.

4. Are there any limitations to using piezoelectric sensors?

One limitation of piezoelectric sensors is that they can only measure dynamic forces, meaning they are not suitable for measuring static forces. Additionally, they are sensitive to temperature and may require temperature compensation. They also have a limited frequency range and may not be suitable for measuring very low or very high frequency vibrations.

5. How can I optimize the use of a piezoelectric sensor?

To optimize the use of a piezoelectric sensor, it is important to carefully select the appropriate sensor for the specific application and to properly mount and calibrate the sensor. Temperature compensation may also be necessary to ensure accurate measurements. Additionally, using signal amplifiers and filters can help improve the signal-to-noise ratio and prevent interference from external sources.

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