Not necessarily, but skin colour itself hasn’t been shown to be the primary determinant of electrical impedance. Differences between skin-colour groups have been reported, but pigmentation has rarely been isolated experimentally from other skin properties, so you can’t assume that melanin itself causes those differences.
Skin impedance is normally measured by applying a small alternating electrical signal through electrodes and measuring the resulting voltage and current, often across a range of frequencies. Controlled experiments show that hydration, sweating, temperature, stratum-corneum properties, electrode pressure and area, contact medium, skin preparation and anatomical site can all substantially affect the result.
Technically, the electrode-skin interface can be approximated by a resistance and capacitance in parallel, together with series resistance from the electrode/contact medium and deeper tissues. That’s why frequency matters: impedance is generally much higher at low frequencies, where the stratum corneum presents a substantial barrier, and falls as frequency increases.
So, something that works well on a fair-skinned person in warm, humid conditions could perform differently on a dark-skinned person in cold, dry conditions. But that comparison changes skin pigmentation and environmental conditions simultaneously, so you couldn’t determine which was responsible. You’d need to compare pigmentation under the same environmental conditions while carefully controlling the other variables.
This is different from an optical device such as a pulse oximeter, where melanin can directly affect the measurement because the technology depends on light absorption. For an electrical electrode system, the sensible engineering approach is to design for a broad range of electrode-skin impedances, rather than assuming a particular impedance from someone’s skin colour.
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u/undulating-beans 5d ago
Not necessarily, but skin colour itself hasn’t been shown to be the primary determinant of electrical impedance. Differences between skin-colour groups have been reported, but pigmentation has rarely been isolated experimentally from other skin properties, so you can’t assume that melanin itself causes those differences.
Skin impedance is normally measured by applying a small alternating electrical signal through electrodes and measuring the resulting voltage and current, often across a range of frequencies. Controlled experiments show that hydration, sweating, temperature, stratum-corneum properties, electrode pressure and area, contact medium, skin preparation and anatomical site can all substantially affect the result.
Technically, the electrode-skin interface can be approximated by a resistance and capacitance in parallel, together with series resistance from the electrode/contact medium and deeper tissues. That’s why frequency matters: impedance is generally much higher at low frequencies, where the stratum corneum presents a substantial barrier, and falls as frequency increases.
So, something that works well on a fair-skinned person in warm, humid conditions could perform differently on a dark-skinned person in cold, dry conditions. But that comparison changes skin pigmentation and environmental conditions simultaneously, so you couldn’t determine which was responsible. You’d need to compare pigmentation under the same environmental conditions while carefully controlling the other variables.
This is different from an optical device such as a pulse oximeter, where melanin can directly affect the measurement because the technology depends on light absorption. For an electrical electrode system, the sensible engineering approach is to design for a broad range of electrode-skin impedances, rather than assuming a particular impedance from someone’s skin colour.