corneometers

A corneometer is a non-invasive instrument used to quantify the hydration level of the skin's outermost layer, the stratum corneum. It is widely used in cosmetic science and dermatology to evaluate skin moisturization and the performance of moisturizers and barrier creams.

Principle: It measures electrical capacitance of the skin surface. The sensor probe emits a small low-frequency electrical field; the dielectric constant of the stratum corneum increases with water content, causing a rise in measured capacitance. The device outputs a numeric value in arbitrary units that correlates with skin hydration.

Procedure and data interpretation: The probe is placed on the skin with gentle, standardized pressure; readings are taken after stabilization and often averaged over several measurements. Values are relative, not absolute, and comparisons are most meaningful within the same protocol and subject.

Applications and uses: In product development and testing to compare moisturizers and delivery systems; in clinical studies to monitor hydration over time; used on facial and body skin, including dry and sensitive skin.

Limitations: Measurements can be influenced by contact pressure, skin temperature, ambient humidity, surface oils, sweating, and individual skin properties. Device-to-device variability exists, and results are correlational with water content rather than a direct measure of total hydration; standardized protocols are essential for reliable comparisons.

Manufacturers: Corneometers are produced by several companies, with Courage+Khazaka electronic GmbH being among the most prominent.