Corneometer

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Corneometer probe with interdigital electrode

A corneometer is a measuring instrument for the quantitative determination of the skin moisture of the upper skin layers . It measures the capacitive AC resistance of the skin.

Measuring principle

Scheme of an interdigital electrode as used in the corneometer.
Field lines (black lines) between two electrode fingers (shown in red and blue) along a cross section of the electrode

An interdigital electrode , which is electrically isolated from the skin, is placed on the skin and an alternating voltage is applied. The impedance of the skin surface is determined from the behavior of the alternating voltage . Since the electric field of an interdigital electrode only penetrates about 10 µm into the skin, the measuring instrument only reacts to the moisture in the upper skin layers. The generally high water content of the deeper tissue does not affect the measurement.

The figure below shows the basic course of the field lines between two fingers of the electrode as long as the electrode is not yet placed on the skin. In this illustration, the skin is placed on the right or left of the two electrodes. Only the field lines reaching out between the two electrodes contribute to the measured value. They lose strength exponentially with increasing distance from the electrodes.

Surname

The term Corneometer is a registered trademark of Courage + Khazaka electronic GmbH . The widespread term corneometry for measuring skin moisture is derived from this brand name . After its invention in 1979, the corneometer has developed into a widely used standard instrument for determining skin moisture. Today (2019) around 5000 scientific publications are known.

See also

literature

  1. ↑ a b G. Khazaka: Assessment of stratum corneum hydration: Corneometer CM 825 , in J. Fluhr, P. Elsner, E. Berardesca, HI Maibach: Bioengineering of the Skin - Water and stratum corneum , CRC Press, 2005, Chapter 20 , Pp. 249-261, ISBN 9780849314438
  2. ↑ Corneometer : Entry of the German trademark No. 1007781 from July 20, 1979
  3. ↑ Triebskorn A., Gloor M., Greiner F .: Comparative Investigations on the Water Content of the Stratum corneum Using Different Methods of Measurement , Dermatologica 1983 (167) pp. 64-69, doi : 10.1159 / 000249750
  4. ↑ Google Scholar search for "Corneometer"