It may be possible, though, to find a material which is at least
minimally conductive (enough to pass a signal in to a high impedance
amplifier) but which does not generate much of a"battery" when in
contact with sweat and skin. I believe that this is a key element in
the design of real EKG electrodes. Perhaps VG could get some of these
electrodes from someone at his university or even find a way to buy a
small quantity.

Sean


On Wed, Mar 9, 2011 at 1:10 PM, Olin Lathrop <olin_piclist@embedinc.com> wr=
ote:
> N. T. wrote:
>> A DC offset, due to the galvanic action, you talked above,
>> is more or less constant thing, you can compensate it in advance, if
>> you know the expected value.
>
> If the DC offset is caused by galvanic action (just a guess on my part, b=
ut
> plausible given the little information we have been given), then it is wo=
n't
> be constant or predictable. =A0It will depend on how sweaty the skin is a=
t
> each electrode, and can shift easily over tens of seconds as the patient
> squirms, etc.
>
> About all you can say is that the galvanic action signal will be lower
> frequency than useful heart signals, so that provides a easy way to
> discriminate between the two. =A0No matter how you spin it, that's going =
to
> take a high pass filter.
>
>
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