Later H.Burak Eral and colleagues in Physics of Complex Fluids group in University of Twente evoked alternating voltage electrowetting to suppress coffee stains noninvasively (i.e. no need to add surface active materials).
Der Ring des Nibelungen | coffee | Ring of Honor | The Fellowship of the Ring | Costa Coffee | The Ring (magazine) | Ring of Fire | The Ring | Ring | Coffee | The Lord of the Rings: The Fellowship of the Ring | ''The Ring'' | Bull Ring, Birmingham | The Promise Ring | Ring 2 | Twin Ring Motegi | Ring Round the Moon | E-Ring | Bull Ring | Sheffield Inner Ring Road | Scarff ring | Ring of Fire (song) | Ring Lardner | One Ring | Ku-ring-gai Council | Cream in My Coffee | World Series ring | Tub Ring | St Martin in the Bull Ring | Ring of Bright Water |