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Effectiveness of sugar as a piezoelectric material Answered

Most of the sites discussing piezoelectricity mention that sugar crystals can be used, but I have not found any examples of them being used. I've just tried it with about a 1cm chunk of low quality (conglomerate of small ~3mm crystals) crystal, and got a good 100mV wave when tapped with a pencil. I've not tried applying a signal to it yet, and some better single crystals are growing at the moment, so I was wondering how well it works compared to commercial piezoelectric compounds.

I've not done anything like this before, so if anyone knows where I can find information of the best way to mount and apply a signal to the crystal, it would be appreciated.

Thanks in advance.

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Can you point us to these sites discussing piezoelectricity mention that sugar crystals can be used?
The charge develops through deformation of the crystal - but it obviously can't deform irreversibly.
Quartz is tough because there's a large degree of covalency in the lattice, sugar is mostly held together by hydrogen-bonds which are much weaker.

L


Hmm, it may be of academic value only.
I've E-mailed my old colleague Ben Davis, let's see what he knows.

L

I would guess that sugar's fragility and hydrophilia stop most people using it.

The individual crystals seem reasonably strong, but I would have to agree that the susceptablity to water damage prevents commercial use. I have thought about giving it a thin layer of wax to seal it, but I guess that it would absorb too much of the energy and make the whole thing ineffective.

That sounds like a better idea, although I don't know whether the sugar will like the solvent in it though. Alternatively, sealing one side of the container with a thin rubber membrane may work better than coating the crystal.

You can test the spray on an ordinary sugar cube.