Contact angle measurement

Advancing and receding contact angle measurements can be carried out by adding and removing liquid from a drop deposited on a surface. If a sufficiently small volume of liquid is added to a drop, the contact line will still be pinne and the contact angle will increase.

Contact angle, θ (theta), is a quantitative measure of wetting of a solid by a liquid. There are three different forces acting on this three-phase contact point between soli liquid and gas, or in some. In the case of the contact angle measurement, the number of data points is the number of recorded pixels along the droplet edge.

As discussed in the first section, this is a product of camera resolution, image magnification, and image clarity.

When a droplet wets well to a surface, it will spread out very flatly. The shape that a drop takes on a surface depends on the surface tension of the fluid and the nature of the surface. The contact angle is a measure of the ability of a liquid to wet the surface of a solid.

At the boundary between droplets and the gaseous environment, the surface tension causes a curved contour. Consider drop of liquid on flat, horizontal surface.

When an interface exists between a liquid and a soli the angle between the surface of the liquid and the outline of the contact surface is described as the contact angle θ (lower case theta). The measurement system is the part that actually measures the contact angle from the image created with the viewing system, and is not a physical part of the instrument.

This is usually done using a software program setup to trace the drop profile and calculate the angle at the contact point.

Contact Angle Measurement System is a tool to study the wetting behaviour of a liquid on Solid. Phenomenon like spreadability, absorption, adsorption, dissolution can be studied by contact angle measurement devices.

Young’s equation only applies to ideal solids with smooth, inert, homogeneous and nonporous surfaces. The capillary rise on a Wilhelmy plate is a good way to obtain the contact angle by measuring the height of the meniscus created on a partially immersed plate.

This animation shows how to create a simple contact angle measuring setup. Usually measurement of dynamic contact angle includes advancing contact angle, receding contact angle and rolling off contact angle. Its value depends on the contact line velocity. In order to avoid ambiguity, this term should not be used for CAs measured by pushing the liquid very slowly in order to obtain advancing or receding values.

The “contact angle”, measured with this type of instrument, refers to the angle created by the surface of a drop of liquid and a flat surface of a known material at the point of contact between the two. The angle is determined by the shape that the drop takes when placed onto the surface. Compared with the traditional measurement instruments, this instrument has the advantage of simplicity, compact size, and portability.

An automatic contact point detection algorithm was developed to allow the instrument to correctly detect the drop contact points. There are equipment available for the measurement of Contact Angle. Various methods are discussed in the attached document, I hope this document can help you.

Using the contact angle meter you can compare the effects of a range of surface treatments and gather data that correlates to various surface conditions e. The Mobile Surface Analyzer – MSA calculates the wettability of a surface automatically by measuring the water contact angle. Chen H(1), Muros-Cobos JL(1), Amirfazli A(1).

Author information: (1)Department of Mechanical Engineering, York University, Toronto, Ontario M3J 1P Canada. However, the method is generally limited to macroscopic measurements because the base diameter of the droplet is usually greater than mm. Here we report for the first time on a dosing system to dispense smaller individual droplets with. Fully automatic contact angle measurement to determine surface tension.

Dynamic measurement of surface tension. Static contact angle.

The static contact angle is the contact angle with which the contact area between liquid and solid is not changed from the outside during the measurement, in contrast to the dynamic contact angle which is produced in the course of wetting (advancing angle ) or de-wetting (receding angle ). The technique of the sessile drop is today the most widely used method to measure this parameter. The commercial softwares available today are still very limited.

They are often dependant of one measurement setup, and may fail under non-standard conditions.