Tewameter TM Hex

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Tewameter® TM Hex

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Transepidermal Waterloss and Skin Barrier Function

Ultimate Measurement of Transepidermal Water Loss and Beyond

The Tewameter® TM Hex (successor of the world-wide popular Tewameter® TM 300) assesses the Transepidermal Water Loss (TEWL), indispensable parameter for the evaluation of the water barrier function of the skin, with a revolutionary accuracy and reproducibility.

30 sensors inside the probe “see” the relative humidity and temperature like a camera. The high amount of data allows the user not only to highly accurately measure inside the probe but can show results also for the areas right outside the probe, namely skin surface and ambience above the probe.

The “open chamber” measurement method is the only method to assess the TEWL continuously without influencing its micro environment.

The Tewameter® probe measures the density gradient of the water evaporation from the skin Δc which is proportional to the TEWL.

The new Tewameter® TM Hex features thirty (30) pairs of sensors which gives 15 x the information from before. The sensors are arranged in 6 columns with 5 sensor pairs each.

The Measuring Principle
A certain evaporation of water from the skin takes always place as part of the normal skin metabolism. As soon as the barrier function of the skin however is slightly damages, the waterloss will increase (even with smallest damages invisible to the human eye). Therefore this measurement is a basis for all cosmetic and dermatological research. The Tewameter® probe measures the density gradient of the water evaporation from the skin indirectly by the two pairs of sensors (temperature and relative humidity) inside the hollow cylinder. This is an open chamber measurement. The open chamber measurement method is the only method to assess the TEWL continuously without influencing its micro environment. A microprocessor analyses the values and expresses the evaporation rate in g/h/m2.

A = surface [m2]

m = water transported [g]

t = time [h]

D = diffusion constant [= 0.0877 g/m(h(mmHg))]

p = vapour pressure of the atmosphere [mm Hg]

x = distance from skin surface to point of measurement [m]
Advantages of the Tewameter® HEX
With this high amount of data for each single measurement and most modern electronics, the probe acts like a camera which “sees” the temperature and humidity distribution, thus giving extremely accurate, reproductive and quick results. Within seconds a robust TEWL value is measured with very low variation & measurement uncertainty.

Measurement uncertainty (Accuracy) Tewameter® TM Hex - extremely low measurement uncertainty known for the complete measurement

For the Tewameter® TM Hex for the time the measurement uncertainty (in g/h/m²) is recorded with each measurement value. This is a unique accuracy feature for a skin measurement tool and it is directly displayed with the robust TEWL in the table.

When you zoom into the TEWL curve, the measurement uncertainty for the whole curve becomes visible as a grey band around the measurement graph.

In addition, through this high data volume, we do not only have knowledge about what is measured inside the probe but can calculate results also for the areas right outside probe, namely skin surface and ambience above the probe.

Thus, the calculation of new, exciting parameters is possible which may give interesting insights in several research fields.
Fields of Application
The measurement of the TEWL and the quality of the barrier function of the skin is the basic measurement for all cosmetic applications.
- Indispensable instrument for formulation, claim support and efficacy testing of skin care, household product, raw materials and pharmaceutical products
- Scalp, lip and hair measurements
- Sweat studies (Anti-Transpirant efficacy)
- It can be used in in vitro testing of skin permeability and dermal absorption necessary for safety and efficacy testing. For this application even a special probe, the In-vitro Tewameter® VT 310 has been developed.
- It is used for dermatological basic research.
- In occupational health it is used to show the quality of the barrier function of the skin and the importance of using skin protection products.
- Veterinary dermatology and zoology.
- The measurement is also used in related industries such as textile or food or paper/tissue industry
New Parameters for Tewameter® HEX
Local Skin Energy Balance

Skin is constantly emitting energy (heat) in two ways: through diffusion of warmed air molecules on top of the skin and through evaporation cooling. For the first time these two can be recorded during a TEWL measurement and displayed separately and in total. The measured values are expressed in W/m².
Water vapor concentration cH20 Skin & Ambience

This parameter expresses the absolute humidity in g/m³. The difference between the value measured on the skin and in the ambience is the drive, the motor for the TEWL. In addition this parameter gives more details about the measurement conditions (e.g. atmospheric turbulences).

In addition also temperature and relative humidity (RH) of the skin surface and in the ambience on top of the probe are measured.
Special Accessories for the Tewameter®
The Tewameter® TM Hex is available as a stand-alone device or connectable to the MPA systems or as a wireless probe.

Other related probes available:
TEWL measurement probe with three measurement chambers, the Tewameter® Triple TM 330T.
In-vitro Tewameter® VT 310 to measure directly on Franz cells
Technical Data
The Tewameter® TM Hex is the first probe out of a new C+K probe generation.

Measurement principle: “open chamber” measurement of evaporation gradient by 30 sensor pairs inside for temperature and RH.
Measurement repeatability (confidence interval 99 %): TEWL: ± (0.15 g/h/m² + 1.0 %)
Measurement uncertainty (max.): TEWL: ± (0.5 g/h/m² + 5.0 %)
Operating conditions: T: 10-40° C, RH: 30-70 % RH

Probe only:
Dimensions:
Measuring Chamber: Height: 2 cm, Ø 1 cm
Probe: Length: 17 cm
Cable length: approx. 1.3 m
Weight: 75 g (including cable)

The Tewameter® TM Hex MDD (Multi Display Device) has to be connected to the PC software for check calibration & zero offset.

The technical data are preliminary and changes may be made without prior notice.

For the dimensions, etc. of the wireless probes, please see the technical data of the basic devices.

Technical changes may be made without prior notice.