Abstract: A method and test apparatus determines a volume of a droplet of liquid. The test apparatus deposits a drop of liquid to be measured on a surface that provides a known contact angle with the liquid under the deposition conditions used, thereby establishing one of: (i) an advancing, (ii) a receding, and (iii) an intermediate contact angle. The test apparatus images the drop. The test apparatus measures a dimension of height or diameter of the drop. In one embodiment, the test apparatus calculates a volume of the drop of liquid from the relationship of the contact angle to one or more parameters selected from the maximum height, the diameter of the contact patch, the radius of curvature, or the cross sectional area of the drop.

Abstract: A method and test apparatus determines a volume of a droplet of liquid. The test apparatus deposits a drop of liquid to be measured on a surface that provides a known contact angle with the liquid under the deposition conditions used, thereby establishing one of: (i) an advancing, (ii) a receding, and (iii) an intermediate contact angle. The test apparatus images the drop. The test apparatus measures a dimension of height or diameter of the drop. In one embodiment, the test apparatus calculates a volume of the drop of liquid from the relationship of the contact angle to one or more parameters selected from the maximum height, the diameter of the contact patch, the radius of curvature, or the cross sectional area of the drop.

Abstract: A method and testing apparatus determine receding contact angles of liquids on surfaces by depositing a liquid in a manner whereby the volume of the drop is increased through stepwise addition of smaller drops. Each increment of volume growth causes the perimeter of the drop to advance across the surface. The incremental volume elements impart sufficient energy to the growing drop such that the drop perimeter expands beyond its equilibrium diameter for that volume. The drop perimeter tends to contract between volume additions as the excess energy is dissipated. The method and testing apparatus determine the receding contact angle between the incremental volume additions.

Abstract: A method and test apparatus determines a volume of a droplet of liquid. The test apparatus deposits a drop of liquid to be measured on a surface that provides a known contact angle with the liquid under the deposition conditions used, thereby establishing one of: (i) an advancing, (ii) a receding, and (iii) an intermediate contact angle. The test apparatus images the drop. The test apparatus measures a dimension of height or diameter of the drop. In one embodiment, the test apparatus calculates a volume of the drop of liquid from the relationship of the contact angle to one or more parameters selected from the maximum height, the diameter of the contact patch, the radius of curvature, or the cross sectional area of the drop.

Abstract: A testing device determines the presence of substances on a surface using a sensor positioned at a known vantage point to the surface. A liquid dispenser deposits a liquid drop on the surface. A data generator after a first time interval for allowing the liquid drop to stabilize on the surface detects, via the sensor, a geometric characteristic of the liquid drop that is related to a first equilibrium contact angle of the liquid drop to the surface. The data generator after a second time interval detects via the sensor the geometric characteristic of the liquid drop that is related to a second equilibrium contact angle. The data generator compares the first and second contact angle and determines a contamination on the surface that is soluble in the liquid drop in response to a change between the first and second contact angles.