Solid State Viscometer

Yesterday I started playing around with a solid state viscometer. This viscometer differs from other more physical methods in that it simply vibrates to determine viscosity. What I did was the following

  • Cut a strip of aluminum sheet.
  • Place a piezo tweeter element on each side
  • Tried to solder the elements to aluminum
  • Soldered two Teflon coated wires to the piezo material
  • Took the whole thing and cast it into epoxy as to seal it and make it rigid between the tow piezo elements.
  • Ground most of the excess epoxy off after curing.
  • hooked a function generator, sine wave, to one side of the unit.
  • Put the oscilloscope on the other side
  • Found the most resonant frequency, which in air, is about 62.5Khz
  • Tried ‘er out!
This is a closeup of the solid state viscometer prototype. You can see I had some problems trying to solder the unit to the aluminum.
This is a closeup of the solid state viscometer prototype. You can see I had some problems trying to solder the unit to the aluminum.
This is the solid state visc in the water. The Epoxy keeps it sealed from the outside and provides rigidity for energy transmission.
This is the solid state visc in the water. The Epoxy keeps it sealed from the outside and provides rigidity for energy transmission.

So far, it seems to provide useful results. I’ve tested it with water and oil. Oil tends to dampen the signal more than water which is a good sign since oil is more viscous but less dense, thus iy’s not functioning (entirely) as a densometer.

Here are the energy differences between water and air, the blue line is the sensor value.

This is the reading for the viscometer in the water. The blue line is the waveform.
This is the reading for the viscometer in the water. The blue line is the waveform.
This is the waveform out of water, the reading is the blue line
This is the waveform out of water, the reading is the blue line

Well, there we have it, a prototype vibratory viscometer. I guess the next step will be to do these three things.

  1. Produce a variable frequency.
  2. Amplify and use the signal appropriately.
  3. Produce a useful number.

Hopefully I’m up to the challenge. 🙂

2 thoughts on “Solid State Viscometer”

  1. I did, though it didn’t take this form. Although with a bit of work this style of viscometer was perfectly sound, I simply didn’t have the time to bring it to a finished state, It was quite accurate though.

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