A millisecond mixing process for liquids was implemented using a new mixer design, i.e., a jet nozzle connected with a trumpet-shaped module. The jet nozzle can facilitate two or three liquid channels, performing an initial impingement mixing of liquid sheets in the thickness at millimeters. Then, the joint liquids sheet out of the jet nozzle was stretched thinner and thinner on the expanded solid surface of the trumpet-shaped module, which significantly intensified the liquid mixing process. Accordingly, dual controls on the liquid mixing can be accomplished flexibly by optimizing the operating conditions and the module configuration. Experiments were carried out to investigate the influencing factors on the mixing performance, where the planar laser induced fluorescence (PLIF) technique was used to measure the mass transport of fluorescent dye between the liquids. The intensity of segregation (IOS) and 95% mixing time (195) were employed to characterize the mixing performance. The results showed that the module with a greater curvature surface possessed a better mixing performance owing to the rapid reduction of the liquid sheet thickness, which strengthened the mixing process in the lateral direction along the flow development. The mixing behaviors are greatly influenced by the flow rate ratio between the liquids. An optimum mixing state could be achieved when Q(S1)/Q(S2) is 1:1. An increase of Q(T) under the same flow rate ratio does not affect the mixing pattern in space, but the corresponding tau(95) is almost linearly shortened. By splitting one liquid stream into two surrounding streams, the so called Sandwich operation brought further improved mixing performance compared with the two liquids mixing process. Using the novel jet nozzle design, millisecond(s) mixing of liquids can be easily achieved with flexible control. (C) 2008 Elsevier Ltd. All rights reserved.