Why Does Human Skin Have Such High Electrical Resistance?

Skin’s outer layer reaches 1,000,000 ohm-m resistivity — while living tissue just beneath it measures a few ohm-m. The surface generates its own negative charge with no external source.

The stratum corneum — the outermost layer of human skin — accounts for more than 99% of the body’s total resistance to electric current. That single, paper-thin sheet of tightly packed dead cells does nearly all the electrical blocking. The living tissue immediately beneath it barely resists at all.

What makes this genuinely strange is the scale of the gap. The stratum corneum’s resistivity ranges from 1,000 to 1,000,000 ohm-m depending on moisture and condition. The viable epidermis and dermis directly underneath measure just a few ohm-m. That is a difference of three to six orders of magnitude, sitting at a boundary thinner than a sheet of paper.

Quick Facts:
– Stratum corneum resistivity: 1,000 to 1,000,000 ohm-m
– Viable skin (epidermis/dermis) resistivity: a few ohm-m
– Skin contact resistance: 1,000 to 100,000 ohms, varying with moisture and pressure
– More than 99% of the body’s electrical resistance originates at the skin
– The skin surface holds a negative transepidermal potential of up to tens of millivolts

How the Stratum Corneum Builds Such Extreme Resistance

Dead cells contain far less water than living tissue. Water and dissolved ions carry electrical current — without them, resistance climbs sharply. The stratum corneum’s tightly packed, largely dehydrated cells create a barrier that blocks ion movement almost completely.

Moisture changes everything. Wet skin resistance drops to roughly 1,000 ohms, while dry skin contact resistance commonly reaches 100,000 ohms. A peer-reviewed study found non-linear electrical behavior in skin beginning at just 0.4 volts, tracing the effect to sweat ducts and the surrounding tissue, with electro-osmosis in those ducts as a proposed mechanism.

The Skin Surface Generates Its Own Electrical Potential

The stratum corneum does not only block current — it holds a charge. The skin surface carries a steady negative transepidermal potential of up to tens of millivolts. No external source produces it. Ion transport through the packed cell layers generates it continuously.

This potential is not passive background noise. Wound-induced electrical signaling in epithelial cells begins approximately 10 minutes after injury, persists for at least 5 hours, and propagates at roughly 10 millimeters per second — reaching up to 500 micrometers from the originating cell. The skin’s built-in electrical field appears to play a direct role in how cells detect and respond to damage.

What Lies Beneath: Subcutaneous Tissue Resistivity

Below the dermis, subcutaneous fatty tissue sits in a middle range — roughly 10 to 100 ohm-m. That is far more resistive than the viable skin layers above it, but still orders of magnitude below the stratum corneum. The body’s internal resistance, by comparison, runs around 300 to 1,000 ohms under dry conditions — confirming that once current passes that outermost barrier, it moves through the body’s fluid-rich interior with relative ease.

The stratum corneum is essentially a resistor and a battery stacked into one layer. It took biology no deliberate design to build it — ion chemistry and cell death assembled it automatically.

The most electrically active surface on the human body is made entirely of cells that are no longer alive.