Description
Corneometer® CM 825
The World's Most Popular Skin Hydration Measurement Instrument
Advantages of the Corneometer® 
- The probe allows very quick measurement (1 s) important to avoid occlusion.
- Continuous measurements over a longer period can optionally be performed.
- Substances on the skin (e.g. salts or residues of topical applied products) have only minimal influence due to capacitance measurement.
- The measurement depth is very small (10-20 μm of the stratum corneum) to exclude the influence of deeper skin layers (e.g. from the blood vessels).
- The probe is small and lightweight for easy handling and measurement on all body sites (e.g. lips etc.).
- The spring in the probe head ensures constant pressure on the skin enabling exact, reproducible measurements.
- The accuracy of the Corneometer® probe and the penetration depth of the scatter field can be checked easily anytime.
- The probe head can quickly be cleaned after each measurement.
- Worldwide established as "corneometry" with a broad range of studies. The Corneometer® had been used to determine the state of the skin of the astronauts on board of the International Space Station (ISS).*
- The Corneometer® is explicitly recommended is the latest guideline for skin water measurements by the experts of EEMCO (European group on efficacy measurement and evaluation of cosmetics and other products) (Skin Research & Technology, 2018, 24, p. 351-358).
The Corneometer® CM 825 is available as a stand-alone device, in the Derma Unit SSC 3, connectable to the MPA systems, or as a wireless probe (please see details in Basic Probe Systems).
*Study by DermaTronnier, instruments verified for space by KayserThrede GmbH on behalf of the DLR space travel management
Measurement Principle
The measurement is based on capacitance measurement of a dielectric medium, here the stratum corneum, the uppermost layer of the skin. With increasing hydration, its di-electric properties change. The measurement is based on the fact that water has a higher dielectric constant (81) than most other substances (mainly < 7).
Gold tracks on top of the in the probe head, separated from the skin by a glass lamina, build-up an electric field between the tracks with alternating attraction. One track builds up a surplus of electrons (minus charge) the other a lack of electrons (plus charge). When put on the skin surface, the scatter field penetrates the very first layer of the skin. The Corneometer® CM 825 measures the change in the dielectric constant due to skin surface hydration changing the capacitance of a precision capacitor. The measurement can detect even slightest changes in the hydration level. Unlike the impedance measurement no galvanic relation between the device and the measuring object and no polarization effects exists.
Fields of Application
The hydration measurement is the basic measurement for all bio-medical and cosmetic applications.
- Ideal instrument for formulation, claim support and efficacy & safety testing of all cosmetics & skin care products (personal care, irritation research, soaps and cleansers, occlusive product development), raw materials, pharmaceuticals, household products, detergents, food and food supplements and many more
- Typical claims (examples) substantiated with the Corneometer®: hydrating/moisturizing, against dry skin, for sensitive skin, protecting, restoring/repairing, supports healing, soothing, normalizing, vitalising, and many more.
- Used as standard in dermatological basis research in humans and animals.
- Occupational health assesses this parameter to underline the importance of skin protection measures.
What are the measurement units?
The Corneometer® measures in arbitrary units from 0 (no water at all) - 120 (on water). The units have been very well establishes as so called "Corneometer units".
What is the penetration depth of the measurement?
The penetration depth of the electric scatter field is demonstrably very small, so that only the moisture on the skin surface is measured. Measurements before and after covering a measuring area with a special foil (15 µm thickness) show that on the foil only 20 % of the original value are measured, the total measurement depth is approx. 40µm. The superficial measurement is important because especially the moisture content in the Stratum corneum is interesting for cosmetic applications.
