The du Noüy ring is a piece of scientific apparatus used to measure the surface tension of liquids. Named after the French physicist Pierre Lecomte du Noüy, it is a key component in the ring detachment method. It is typically made of platinum or platinum-iridium alloy to ensure cleanliness and avoid contamination, and is usually about 10-20 mm in diameter.
The ring is suspended from a torsion balance or force sensor. The ring, in a horizontal plane, is dipped into the liquid and slowly lifted. As it exits, a thin film of liquid forms. The force required to detach the ring from the liquid’s surface is measured, correlating with the liquid’s surface tension.
You can see the methodology in action at the beginning this video, which demonstrates it using our Sigma 700/701 Force Tensiometers from our partners Biolin Scientific.
You can read more about Surface tension measurement by du Noüy ring method on this blog post by Susanna Laurén.
The du Noüy ring method is simple and straightforward to perform, suitable for a wide range of liquids (especially low-viscosity ones), and provides quick results. It offers wide compatibility with various liquids, and is well-established with standardised procedures, making it a reliable and versatile technique for measuring surface tension.
The Sigma Force Tensiometers simplify, automate and make your surface tension measurements more efficient. Visit us so we can demonstrate one.
