Drop Angle Meter DM 300

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

The instrument used to measure the wettability of the skin’s surface, and the concerned liquid is called a drop angle meter. It has a comfortable rest on which the person needs to rest his forearm. This surface can be tilted or moved vertically to ensure the liquid drop on the skin does not disintegrate.

A high-resolution camera and a uniformly diffused LED light source are combined with the main device. The camera takes the shot in a way where the interaction of the liquid with the skin’s surface is easily captured. This picture is then used for further analysis, i.e., determining the contact angle and wettability.

Drop Angle Meter DM 300

What is the drop angle of a liquid?

When liquid is at rest, its surface acts as a stretched membrane due to the forces of attraction between the water molecules and the atmospheric pressure in the downward direction. This physical activity is termed surface tension.

Two types of forces act on the liquid molecule when it comes in contact with another surface or solid. The force acting between the molecules of the same substance is termed a force of cohesion, while the force acting between the molecules of different substances is termed a force of adhesion.

It is due to the action of these two forces one can find liquid forming droplets and holding their spherical shape when poured over a surface like mercury. On the other hand, sometimes the liquid can spread and fails to hold its shape as you continue to increase the spherical shape, like water.

drop angle

Application of drop angle-metry?

On many occasions, the skin’s wettability, hydrophilic properties, tension, and surface energy need to be calculated. To do so, the drop angle meter is measured. In physical terms, the contact angle is defined by the total value of the angle formed at the intersection of gas, liquid, and solid, also known as the three-phase plane.

Based on this value, the wettability of the surface can be determined. It is defined as the ability of the liquid to maintain physical contact with the solid surface. It can be divided into two types.

1- Repellence wettability: It is a condition where the force of cohesion between the liquid molecules is more than the force of adhesion between the solid surface and the liquid molecules. Therefore, the liquid continues to hold its spherical shape, even when they are in contact.

2- Spread ability: It is a physical condition where the force of cohesion between the liquid molecules is less than the force of adhesion between the liquid and solid surface molecules. Therefore, liquid can spread on the surface by increasing the spherical radius instead of holding the sphere shape.

Method of determining the contact angle

The Youngs equation defines the relationship between the skin’s surface free energy, contact angle, the interfacial tension between the liquid and the skin, and the liquid’s surface tension. It is defined as:

γS = γL cosθ + γSL

Here, θ is the contact angle,

γS is the surface free energy of the concerned solid,

γL is the surface tension of the concerned liquid,

and γSL is the interfacial tension between the solid surface and the liquid.

The larger the contact angle the lower the wettability, the lower the contact angle the better the wettability.

According to the standard measures, if the contact angle is less than 90 degrees, the solid features a hydrophilic surface; if the angle is more than 90 degrees, it is known to have a hydrophobic surface. Therefore, wettability is indirectly proportional to the contact angle.

To relate above said definition to skin, higher wettability indicates more moisture on the skin level. It would be also related to the sebum content of the skin, because 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.

Where to use

  • Effects of detergents, moisturizers, and other products on the skin
  • Testing the extent to which the products can spread
  • Repellence degree testing
  • Tissue engineering for the skin grafting process
  • Hair care since the hair strands are coated with a hydrophobic layer

Quick fact Drop Angle Meter DM 300

  • Flexible and compact instrument to measure the skin’s wettability
  • High-resolution camera for sharper images of the drop on the surface
  • Modern software backed by an accurate algorithm
  • Can measure the wettability of skin and several other materials
  • The focus of the camera can be changed flexibly
  • Allows live calculation of the drop contact angle and spherical dimensions
  • Unique feature: Add Corneometer® and Tewameter® measurements in the same software to get complete skin water-related information. Indispensable to compare measurements over time.
  • Video recording
  • Evaluation of all datasets in a single click
  • Check calibration helps to detect the changes in scale calibration

Technical data

  1. Dimension of the devices: 52 × 32 × 27 cm³ (L x W x H),
  2. Weight of the device: 9 kg, approximately
  3. External power supply requirement (input): 100-240 V, 47-63 Hz
  4. External power supply requirement (output): DC 12V/4A
  5. Port needed/supported: USB 2.0 with type B connector
  6. Camera lens and specifications: 1/2″ B/W CMOS-sensor
  7. Camera resolution: 1.3MP (1280 x 1024 pixels)
  8. Illumination area of the white LED light: 11 x 11 cm
  9. Supported computer device: Windows® 10, USB 2.0/3.0