> Not quite. The amount of charge movement is proportional to the force.
> The amount of current is proprotional to the rate of change.

Right.  The charge only moves once as the load is changed.

> If you had a very high impedance input buffer, the voltage across
> the piezo would be proportional to the force.

Yes, because you are integrating the charge.

Looking back I was a little sloppy in my original statement, but I think
we are basically agreeing.  The end result is the same, a piezo sensor is
not useful for absolute static measurements because the integrator initial
value is unknown, and any real physical components will have leakage.
With any real circuit, there will be a frequency below which a piezo
sensor is not useful.


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