Changes in the skin's capacitance after damage to the stratum corneum in humans

Wound healing is a complex process to study, especially in humans, because the endpoint(s) of wound-induction and healing are subjective and, therefore, difficult to quantitate. Experiments were performed to establish quantifiable endpoints during the wound-induction process in 15 humans (11 women, 4 men).

Measurement of the skin's capacitance was used as a marker for the three stages of wound healing: 1) establishment of a wound, 2) the healing process, and 3) complete re-epithelialization.

Superficial wounds in the epidermis were generated by tape stripping the skin on the arm of 15 healthy volunteers. The skin's capacitance was measured before tape stripping, at various time points during the induction of the wound, immediately after glistening of the epidermis was achieved, and when the wound had healed according to clinical assessment.

The values of the skin's capacitance at the point of removal of the stratum corneum varied from one individual to the next. Furthermore, the number of adhesive cellophane-tape strips needed to remove the stratum corneum and achieve glistening, due to accumulation of moisture, differed greatly from one volunteer to the next. These experiments suggest that the number of tape strips needed to remove the stratum corneum varies with age, sex, and possibly ethnicity of the subject. By contrast, during the wound healing process when a scab could be visualized, the skin's capacitance measured -122 picofarads (pF). Moreover, when the scab had disappeared, the skin's capacitance returned to baseline values (0 pF).

Measurement of the skin's capacitance is a useful tool to determine two endpoints in the wounding and healing processes. The presence of a scab and the re-establishment of an intact stratum corneum can be quantitated easily. Less amenable to quantitation is the exact pF value that correlates to a specific type of wound.