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Force platforms should be distinguished from pressure measuring systems that, although they too quantify centre of pressure, do not directly measure the applied force vector. Pressure measuring plates are useful for quantifying the pressure patterns under a foot over time but cannot quantify horizontal or shear components of the applied forces. [2]
The Wilhelmy plate consists of a thin plate usually on the order of a few square centimeters in area. The plate is often made from filter paper, glass or platinum which may be roughened to ensure complete wetting. In fact, the results of the experiment do not depend on the material used, as long as the material is wetted by the liquid. [1]
The Wilhelmy method consists of a plate partially immersed in the liquid connected to an electronic linear-displacement sensor, or electrobalance. The plate can be made of platinum or filter paper which has been presoaked in the liquid to maintain constant mass. The plate detects the downward force exerted by the liquid meniscus which wets the ...
The Wilhelmy plate tensiometer requires a plate to make contact with the liquid surface. It is widely considered the simplest and most accurate method for surface tension measurement. Due to a large wetted length of the platinum plate, the surface tension reading is typically very stable compared to alternative methods.
The electrostatic double layer force decays in an exponential fashion. Due to the screening by the electrolyte, the range of the force is given by the Debye length and its strength by the surface potential (or surface charge density). This approximation turns out to be exact provided the plate-plate separation is large compared to the Debye ...
Wilhelmy plate method: A universal method especially suited to check surface tension over long time intervals. A vertical plate of known perimeter is attached to a balance, and the force due to wetting is measured. Spinning drop method: This technique is ideal for measuring low interfacial tensions. The diameter of a drop within a heavy phase ...
A force plate gathers data in the anterior-posterior direction (forward and backward), the medial-lateral direction (side-to-side) and the vertical direction, as well as moments about all 3 axes. Together, these can be used to calculate the position of the center of pressure relative to the origin of the force plate.
The advancing and receding contact angles can be measured directly using different methods and can also be calculated from other wetting measurements such as force tensiometry (aka Wilhemy-Plate method). Advancing and receding contact angles can be measured directly from the same measurement if drops are moved linearly on a surface.