A Novel Dosing Solution for Extremely Fast Surface Free Energy Measurements

Krüss GmbH has developed a novel, double-dosing system for performing wetting analyses on solid surfaces. Used in conjunction with Krüss contact angle measuring instruments, the DS3252 dosing module performs fully automated surface free energy (SFE) determinations within a second. Such extremely short measurement times make this new dosing solution particularly suitable for quality assurance processes during cleaning, pretreatment and coating of solid materials. The system’s precise, reproducible analyses and scientific evaluation methods offer powerful benefits for research and development as well.

Available from April 2015, the dosing unit has two pressure dosing mechanisms working in parallel, each simultaneously dispensing one drop of the test liquids water and diiodomethane onto the sample. As the volumes involved are highly precise and the kinetic energy is minimal, the process, despite its speed, is equivalent to gently dispensing a drop from a dosing needle. Most importantly, this non-contact method eliminates the risk of contamination or damage caused by inadvertently touching the sample. Cartridges that operators can remove quickly and fill directly with test liquids make the dosing system easy to handle. One filling is enough for approximately 1000 SFE determinations.

The evaluation method developed alongside the double-dosing system also contributes to the speed of the assay: the image field of the high resolution camera is split into two video windows for viewing both drops at the same time in order to analyse the drop contours in parallel. The software then uses the resulting contact angles to calculate the SFE of the solid. The entire process, from the point when dosing starts up to the SFE calculation, is fully automatic and complete within a second. Krüss has two patents pending, one for this innovative ‘One-Click SFE’ method and one for the novel dosing technology.

The analysis sequence is defined in a measurement template, which can be generated quickly and easily. If the measuring instrument is suitably equipped, this sequence can be combined with any software-controlled sample stage movements, enabling fully automatic sample analyses with predefined measurement positions. With such an easy-to-prepare test sequence for a highly automated system, operator errors are almost ruled out.