Skin surface electric potential as an indicator of skin condition: a new, non‐invasive method to evaluate epidermal condition

Abstract

We previously demonstrated that the skin surface electric potential, which has been long recognized as a parameter of emotional or physiological state, is generated by epidermal keratinocytes and is strongly associated with the ion concentration gradient in the epidermis. Thus, at temperatures below the threshold of sweating, the potential provides a measure of the epidermal ion concentration gradient, which in turn is related to epidermal homeostasis and pathology. In the present study, we established a new, non-invasive method to measure skin surface electric potential. In healthy skin, calcium ion was localized in the uppermost epidermis and the gradation disappeared by tape stripping. Skin surface potential was also disappeared by tape stripping. Moreover, environmental humidity affected the potential, whereas temporary hydration of the stratum corneum did not affect it. These results suggest that the skin surface electric potential may be an indicator of the pathophysiology of the living layer of epidermis, and thus may be useful as a new parameter to evaluate skin condition.

Minimally-invasive transepidermal potentiometry with microneedle salt bridge

“…Skin barrier disruption by these treatments was confirmed by measuring the change of transepidermal water loss (TEWL) (≥50 % increase). Figure 4(b) clearly shows both the treatments reduce the TEP, which is consistent with the reported typical response of living skin (Kawai et al 2008(Kawai et al , 2011. Obtained TEPs had small variance and showed high reproducibility of the measurement.…”

“…In fact, disturbances on the skin such as aging and physical damage of the skin surface have been known to affect TEP. (Barker et al 1982;Denda et al 2001;Kawai et al 2008Kawai et al , 2011Dubé et al 2010;Moulin et al 2012).…”

“…Conventionally, the inner electrode is placed on a wound with exposed dermis that is surgically created (Barker et al 1982;Dubé et al 2010;Moulin et al 2012). As a non-invasive alternative to the surgically exposed dermis, the inner electrode can be placed on a sublingual area, and this method proved effective in evaluating variation of TEP (Kawai et al 2008(Kawai et al , 2011. For the measurement of absolute TEP, it is desirable to juxtapose the inner electrode with the surface electrode in order to suppress iR drop generated in dermis and other tissues.…”

Sensory Systems of Epidermal Keratinocytes

“…Moreover, environmental humidity affected the potential, whereas temporary hydration of the stratum corneum had no effect. These results suggest that the skin surface electrical potential may be an indicator of the pathophysiology of the living layer of epidermis, and thus may be useful as a new parameter to evaluate skin condition [ 70 ] . Further, the calcium gradient in the epidermis disappears in aged skin [ 36,47 ] and in experimentally induced dry skin [ 48,68 ] .…”

“…On the other hand, skin surface electrical potential is considered to refl ect the pathophysiological condition of the epidermis [ 70 ] . Skin surface electrical potential has long been recognized as a parameter of emotional state [ 82 ] , and it was believed that sweat glands generated the potential [ 115 ] .…”