▁version ▁of ▁the ▁du ▁No ü y ▁ring ▁method ▁replacing ▁the ▁large ▁plat in um ▁ring ▁with ▁a ▁thin ▁rod ▁that ▁is ▁used ▁to ▁measure ▁equilibrium ▁surface ▁t ension ▁or ▁dynamic ▁surface ▁t ension ▁at ▁an ▁air – liqu id ▁interface . ▁In ▁this ▁method , ▁the ▁rod ▁is ▁orient ed ▁per pend icular ▁to ▁the ▁interface , ▁and ▁the ▁force ▁ex ert ed ▁on ▁it ▁is ▁measured . ▁Based ▁on ▁the ▁work ▁of ▁P add ay , ▁this ▁method ▁finds ▁wide ▁use ▁in ▁the ▁prepar ation ▁and ▁monitoring ▁of ▁Lang mu ir – Bl od get t ▁films , ▁in k ▁& ▁co ating ▁development , ▁ph arma ce ut ical ▁screen ing , ▁and ▁academic ▁research . ▁ ▁D etailed ▁description ▁The ▁du ▁No ü y ▁P add ay ▁rod ▁consists ▁of ▁a ▁rod ▁usually ▁on ▁the ▁order ▁of ▁a ▁few ▁mill im eters ▁square ▁making ▁a ▁small ▁ring . ▁The ▁rod ▁is ▁often ▁made ▁from ▁a ▁composite ▁metal ▁material ▁that ▁may ▁be ▁rough ened ▁to ▁ensure ▁complete ▁wet ting ▁at ▁the ▁interface . ▁The ▁rod ▁is ▁clean ed ▁with ▁water , ▁alco hol ▁and ▁a ▁fl ame ▁or ▁with ▁strong ▁acid ▁to ▁ensure ▁complete ▁removal ▁of ▁sur fact ants . ▁ ▁The ▁rod ▁is ▁attached ▁to ▁a ▁scale ▁or ▁balance ▁via ▁a ▁thin ▁metal ▁hook . ▁The ▁P add ay ▁method ▁uses ▁the ▁maximum ▁pull ▁force ▁method , ▁i . e . ▁the ▁maximum ▁force ▁due ▁to ▁the ▁surface ▁t ension ▁is ▁recorded ▁as ▁the ▁pro be ▁is ▁first ▁imm