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Courage + Khazaka electronic GmbH

Drop Angle Meter DM 300

Compact, high-quality instrument for analyzing wettability and spreadability of materials on the skin

Characterizing the shape of a drop of water on a surface and determining its contact angle is a well-known method to analyze wettability, skin’s free surface energy, its tension and its hydrophilic/hydrophobic properties.

Wettability is the ability of a liquid to maintain contact with a solid surface. Wettability can be wanted or not (repellence or spreadability).

  • Method

    When a defined droplet is applied to a solid medium (here: skin), the liquid forms a certain shape (drop shape). The point at which the skin, liquid and air meet determines the contact angle.drop shape measurement by contact angleThe relationship between the contact angle, the skin surface free energy, the liquid surface tension and the interfacial tension between skin and liquid is defined by Young’s equation:

    γS = γL cosθ + γSL

    θ: Contact angle
    γS: Surface free energy of the solid
    γL: Surface tension of the liquid
    γSL: Interfacial tension between solid and liquid

    The larger the contact angle the lower the wettability, the lower the contact angle the better the wettability. In literature the relation between wettability of a substance and contact angle are defined as follows:

    • Contact angle < 90° = hydrophilic surface
    • Contact angle > 90° = hydrophobic surface
    Translated for the skin, higher wettability indicates more moisture at the skin surface. It is also linked to the sebum content of the skin as sebum makes the skin more hydrophilic. Dry skin shows correspondingly lower wettability. Skin surface free energy and wettability are also related. Skin with lower surface energy generally shows lower wettability properties.



    high                          contact angle                                                          low
     low wettability high
     low adhesiveness high
     small skin’s free energy large
  • Device

    With the Drop Angle Meter, the inner forearm is Drop Angle Meter DM 300placed on a comfortable rest, which can be moved vertically and tilted in order to have the skin surface where the drop is applied to absolutely levelled to prevent the water from running or disintegrating. The compact system features a very uniform diffuse LED light source and a high-resolution camera, which takes the macro image of the drop on the skin from the side, which is then automatically analyzed in the software. All data, images, and even videos are saved in the database and can conveniently be filtered and exported.
    Drop shape measurement before and after application of moisturizer

    The camera can be moved in x, y and z direction (up and down as well as back and forth and vertically), to perfectly match the best depth of focus for each drop size. The solid system features height adjustable feet to compensate unevenness of the working surface.

  • Advantages of the System

    • Compact, flexible system to analyse skin or Drop Angle Meter Corneometer and Tewameterother material.
    • High resolution, sharp image of the drop.
    • Measurements not only on skin but also on other material are easily possible with a supplied support.
    • Modern and convenient software
    • Very easy focusing of the camera.
    • Live calculation of contact angle and dimensions of the drop.
    • Videos of the drop placement can be taken
    • Unique feature: Add Corneometer® and Tewameter® measurements in the same software to get complete skin water-related information. Indispensable to compare measurements over time.
    • Convenient organisation of images and results in studies. Evaluate all data together by one click.
    • Intuitive, illustrated check calibration function.
  • Fields of Application

    • Effect of products on the skin (degreasing, washing, moisturizing)
    • Testing of the spreadability of products
    • Testing of water repellence of (cosmetic) products, for example lip gloss or nail polish
    • Tissue engineering, e.g. skin grafts for scars (improved adhesion of cells with increased wettability)
    • Human hair is enclosed by a hydrophobic protective layer. Hair care is supposed to remove contamination, but to leave the hair protected or enclose it in a smoothing coating. Hair care products hydrophobicity can be tested by drop shape measurements on carrier plates.*
    wettability efficacy testingDM arm with dropWash hairDM on material

    * In a study (F. Bollon - Gattfossé, Let your hair down with a new texture, Personal Care Magazine, January 2022) a hair care emulsion was applied on a glass plate. After drying for 3 hours at 23°C and 30 % RH the hydrophobic properties of the active agent could be demonstrated by drop shape measurements.

  • Technical Data

    Dimensions: 52 × 32 × 27 cm³ (L x W x H), weight: approx. 9 kg, external power supply: input: 100-240 V, 47-63 Hz, output: DC 12V/4A, port: USB 2.0 type B connector, camera: 1/2" B/W CMOS-sensor 1.3MP (1280 x 1024 pixels), illumination: 11 x 11 cm, white LEDs

    Computer: Windows® 10, USB 2.0/3.0, computer specifications must meet system requirements (please ask for details).

    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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