At 06:05 PM 7/1/99 -0400, you wrote:
>>         The obvious flaw in your hypothesis is that the current flowing
>through
>> the 'tissue'
>> will also flow through the skin as well. Once the tissue becomes
>conductive
>> it is a resistance in parallel with the skin it is in contact with... <G>
This assumption is based on the tissue absorbing moisture from the skin...
not removing moisture from the skin. If the skin is moist enough to supply
moisture to the tissue then BOTH  the skin and the tissue contain moisture
therefore they are two parallel resistors.
As you postulate NO method to keep the skin dry for example a type of
semipermiable membrane. By the postulated defination both the skin and the
tissue are (of necessity I believe for measurement accuracy) at the same
level of moisture content...
Perhaps this will clarify my "understanding of the design" <BG>

>There is an obvious flaw in your understanding of the design ;-)
>
>The current does not flow through the skin because the dry tissue insulates
>the electrodes from the skin.  The tissue is against the skin and the
>electrodes are *on top* of the tissue.  They do not touch the skin.  The
>electrodes are measuring the resistance of the tissue only.  The dry
>resistance of the tissue will be very high.  The wet resistance of the
>tissue, particularly when wet with sweat, will be much, much lower.  The
>purpose of the tissue is twofold:  (1) it enhances the difference in
>resistance between wet and dry state, and (2) it alleviates the necessity
>for current flowing continuously through the skin.
>
>Best regards,
>Michael
>
>R. Michael O'Bannon, Ph.D.
>Clinical and Corporate Psychologist
>Atlanta, GA  30324