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skin resistance
All measurements performed with spectra 360 electrogel.
Measurement setup: pulsed sine wave, 3x3cm conductive rubber on skin.
Conclusion: skin resistance depends on frequency as well as current. When using large conductive rubber pads at normal frequencies total resistance is around 500Ω. This can drop to 200Ω when frequencies are higher.
This includes the resistance of the rubber itself.
I repeated the measurements above, but live meat was replaced with a stainless steel bar.
In this configuration frequency does not play a very big role.
I tested conductive rubber on an aluminium plate with electrogel and DC. This configuration acts as a diode, current only flows one way and there's a minimum voltage before it starts conducting.
Copper electrodes differ from rubber electrodes. At higher frequencies, the curves are much more flat.
with 22ohm current sensing resistor.
rubber on skin, 1000hz
rubber on skin, 1000hz, more gel
Copper on skin, 1000hz
Copper on skin, 4000hz
- The skin acts as a diode, above a certain voltage the dielectric properties of the skin break down and the resistance decreases.
- The properties of the skin depend on the material in contact with the skin as well as the frequency.
- Additional wetting appears to increase capacitance of the skin.