What Does It Measure? Characterizing the shape of a drop of water on a surface like the skin and determining its contact angle is a well-known method to analyse wettability, skin’s free surface energy, its interfacial tension and its hydrophilic/hydrophobic properties. Contact angle < 90° = hydrophilic surface Contact angle > 90° = hydrophobic surface The Principle When a defined droplet is applied to a solid surface, the liquid forms a certain drop shape. The point where the surface, liquid and air meet, determines the contact angle. The 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: Fields of Application • Effect of products on skin and hair (degreasing, washing, moisturizing). • Testing of the spreadability of products. • Water resistance of products (e.g. sunscreen). • Testing of water repellence of (cosmetic) products (e.g. lip gloss or nail polish). • Tissue engineering, e.g. skin grafts for scars (improved adhesion of cells with increased wettability). θ: Contact angle γS: Surface free energy of the skin γL: Surface tension of the liquid γSL: Interfacial tension between surface and liquid Higher wettability indicates more moisture at the skin surface (higher skin surface free energy). Dry skin shows correspondingly lower wettability. Technical Data Dimensions: 52 x 32 x 27 cm; Weight: 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® 10/11, USB 2.0/3.0, computer specifications must meet system requirements. Technical changes may be made without prior notice. Advantages • Compact, flexible system to analyse skin or other material. • High resolution, sharp image of the drop. • Modern and convenient software • Very easy focussing of the camera. • Live calculation of contact angle and dimensions of the drop. • Videos of the drop placement can be taken. • Add Corneometer® and Tewameter® measurements in the same software to get complete skin water-related information. • Convenient organisation of images and results in studies. Evaluate all data together by one click.