Courage + Khazaka electronic GmbH

Tewameter® TM 300


worldwide most used method "open chamber"

Transepidermal Water Loss and Skin Barrier Function

The Tewameter® TM 300 with its “open chamber” principle is the worldwide most accepted measuring device for the assessment of the Transepidermal Water Loss (TEWL). This is an indispensable parameter for the evaluation of the water barrier function of the skin and a basic measurement in all kinds of applications. Even the slightest damage in the skin water barrier can be determined at an early stage.

  • Advantages of the Tewameter®

    • Extremely accurate and quick measurement of the TEWL without any influences of the micro climate of the skin (pressure, occlusion, temperature).
    • The small size of the probe head minimizes the influence of air turbulence inside the probe.
    • Its low weight has no influence on the skin structure and ensures easy handling.
    • No waiting time between the measurements.
    • Traceable, sophisticated calibration of humidity, temperature and TEWL to g/h/m2.
    • A stable measurement is achieved quickly; continuous measurements over longer periods are also possible depending on the application.
    • The continuous development of the measurement values and average and standard deviation over time are always visible. Display of RH and °C separately for upper and lower sensor.
    • Worldwide most used TEWL measurement method (even approved in space!*). Several hundreds of performed studies with the Tewameter® prove this fact.Tewameter® used on the International Space Station ISS
    • The Tewameter® 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).
    • Recording of the ambient conditions with the Ambient Condition Sensor RHT 100 to help to compare measurements taken at different points in times.
    • With the open chamber measurement even higher water loss values can be detected accurately as no water is collected inside the probe.
    • Special calculations i.e. SSWL (Skin Surface Water Loss - assessment of skin's water holding capacity after occlusion) are possible.
    • Accuracy of the probe can be checked anytime quickly.
    • Offset function to compensate "aging effects" of the probe.
    • You can use several Tewameter® probes at the same time.
    • Accessories for the measurement or hygienically cleaning are available.
    • Innovative in vitro measurement possibilities.
    The Tewameter® TM 300 is available as a stand-alone device, 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
    Tewameter® measurements
    Tewameter®  - measurement of water binding capacity
    Ambient Condition Sensor - very useful for TEWL measurements
    Tewameter® MDD stand-alone device
    Tewameter® as wireless probe
    Other related probes available:
    • Tewameter® Triple TM 330T: TEWL measurement probe with three flexible measurement heads to measure either on a large surface or on three different surfaces simultaneously.
    • Tewameter® TM Nano: ideal tool for small or difficult to reach skin sites (e.g. nail, lips, scalp with hair).
    • Invitro Tewameter® VT 310: measurement of TEWL directly on Franz cells.
    • Tewitro® TW 24: TEWL measurement on up to 24 cultured skin wells simultaneously.
  • Measurement Principle

    Tewameter principle

    A certain evaporation of water from the skin takes always place as part of the normal skin metabolism. However, as soon as the barrier function of the skin is slightly damaged, the water loss 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. This method is the only to assess the TEWL continuously without influencing its micro environment. The measured values express the evaporation rate in g/h/m2.
    Tewameter formulaA = 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]

  • 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 as a basic safety test.
    • Typical claims (examples) substantiated with the Tewameter®: skin barrier improving/enhancing/restoring/repairing, protecting, soothing, supports healing, for sensitive skin, normalizing, anti-irritation, anti-pollution, and many more.
    • Sweat studies (anti-perspirant efficacy)
    • It is used in in vitro testing of skin permeability and dermal absorption necessary for safety and efficacy testing. For this application even special probes, the Invitro Tewameter® VT 310 to measure directly on Franz cells and the Tewitro® TW 24 to measure simultaneously in up to 24 cultured skin wells have been developed.
    • It is used as standard in dermatological basic research in humans and animals.
    • In occupational health it assesses the quality of the barrier function of the skin and is used to show the importance of using skin protection products.
    • Veterinary dermatology and zoology use this measurement successfully.
    • The measurement is also used in related industries such as textile or food/food supplement, packaging or paper/tissue industry.
    Tewameter® - basic device for cosmetic tests
    Tewameter® - measurements throughout the body
    Tewameter® - measurements on baby skin
  • Probe Heater PR 100

    Probeheater - SondenwärmerThe sensors of the probe normally have room temperature (20-22°C), whereas skin temperature is 30°C and higher. As the amount of evaporating water measured with the device is extremely small (healthy skin 8-15 g/h/m² → 0.000001333 - 0.00000025 g/minute/cm²), the sensors inside the probe should reach skin temperature to measure this small amount exactly and stable. With the probe heater the probe head is constantly warmed up to a temperature close to skin temperature and thus getting very quickly accurate and stable results.

    sensors inside the probe cold (room temperature)

    sensors inside the probe cold (room temperature)

    sensors preheated to 30°C - stable measurement in an extremely short time

    sensors preheated to 30°C - stable measurement in an extremely short time

  • In vitro measurements with the Tewameter®-Family

    The Tewitro® TW 24 is the only device to measure the water evaporation from cultured tissue sets (wells in a plate with medium) in up to 24 wells simultaneously with the worldwide most used open chamber measurement of the Tewameter®.
    Indispensable tool for safety, sensitivity and efficacy measurements to avoid using animals or volunteers.
    Fully equipped, the Tewitro® TW 24 can be used in 24 wells plates (6x4). The probe features 6 slots with 4 measurement inlets each, but is also available as single rows of 1 slot with 4 measuring inlets (respectively for 8, 12, 16 or 20 inlets), depending on the used well plate size. The convenient and organized software offers 24 TEWL-values (one for each measurement inlet), with two different adjustable averages and their respective standard deviations as well as the possibility of displaying and saving the RH and temperature value for the upper and lower sensor pair for each measurement inlet (2 x 24) separately. A graphical view for each measurement inlet is available with one click.

    Tewitro® - measurements in up to 24 cell cultures simultaneously
    convenient and detailed display of all measurement inlets
    Tewitro® - innovative, new method for in vitro measurements

    With the Invitro Tewameter® VT 310 a probe for the TEWL measurement is available, which offers all benefits of the Tewameter® and is perfectly suited to sit on a Franz cell. It emulates completely the upper part (donor chamber) of a Franz cell (standard is 15 mm Ø, other sizes on request).Thus the probes sits exactly on the membrane of the Franz cell as it would sit on skin directly without needing further adapters. The measured TEWL-value is expressed in g/h/m², the worldwide acknowledged absolute measuring value for skin. No other probe offers this possibility. If needed, the probe can also be used on a centerpiece of high quality Teflon, which fits exactly on the probe and the receptor chamber of the Franz cell without further fixing adapters. The thus measured TEWL has to be regarded relatively (no longer absolute figures as the distance between probe and membrane is changed).

    Invitro Tewameter® fits perfectly to Franz cells
    Invitro Tewameter®
    Invitro Tewameter® with special center piece

    In vitro TEWL measurements have a variety of different applications:

    • Inexpensive pre-screening before in vivo tests (no ethic commission, no expensive volunteers)
    • Only way to study skin permeability and dermal absorption necessary for safety and efficacy testing
    • In vitro tests are established in several worldwide acknowledged guidelines: e.g. ECVAM (European Centre for the Validation of Alternatives to Animal Testing) or OECD (Organisation for Economic Co-operation and Development)
  • Special Accessories for Tewameter® TM 300

    There are special adapters available for the probe.Tewameter adapter small

    • An adapter with smaller opening is available for different applications e.g. measurement on small animals or small skin sites (reduced the measurement area to 2 mm Ø). For measurements in g/h/m² on small skin sites (e.g.

      Tewameter ring

      nail, lips, scalp with hair), please also read about the Tewameter® TM Nano.
    • Disinfectable steel rings are available when measuring on special surfaces. They can be mounted on the measuring head and after the measurement taken off the probe and be cleaned.

  • Technical Data

    Probe only:

    Dimensions: Measuring Chamber: 2 cm, Ø 1 cm, Probe: 15.3 cm, Cable length: approx. 1.3 m, Weight: 90 g, Resolution: Humidity: ± 0.01 % RH, Temp.: ± 0.01 °C, TEWL: 0.1 g/h/m²

    Measurement uncertainty for TEWL-values lower than 70 g/h/m²:

    rel. humidity (RH): ± 1.5 % for RH between 30 % and 90 %, ± 2.5 % for RH between 90 % and 100 % and for RH between 10 % and 30 %

    Waterloss: ± 0.5 g/h/m² for RH ≥ 30 %; ± 1.0 g/hm² for RH ≤ 30%,

    Temperature: ± 0.5 °C

    Probe Heater PR 100: Power supply: external 100-240 VAC, 47-63 Hz, DC 12V/4A, Dimensions: 10 x 11 x 10.5 cm, Weight: 470 g

    Operating conditions: T: 10-40° C, RH: 30-70 % RH

    For the technical data of the wireless probe, please see Basic Probe Systems.

    Technical changes may be made without prior notice.

Courage+Khazaka electronic GmbH
Mathias-Brüggen-Str. 91
50829 Köln, Germany
Phone: +49-221-9564990
Fax: +49-221-9564991
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