An oscillating feedback micromixer with no moving parts comprises an inlet channel, a diverging mixing chamber, a splitter, two feedback channels, and an outlet channel. Using the Coanda effect, two liquids are passively mixed in an oscillating feedback micromixer. Three oscillating feedback micromixers were experimentally investigated using two miscible liquids. The first had asymmetric feedback channels and a splitter, the second had symmetric feedback channels and a splitter, and the third had symmetric feedback channels and no splitter. Three chaotic mixing modesvortex mixing, internal recirculation mixing, and oscillating mixingwere observed with increasing Reynolds numbers. The asymmetric oscillating feedback micromixer was determined to have the best mixing performance among the three micromixers. The splitter and asymmetric feedback channels can facilitate internal recirculation through feedback channels and fluidic oscillation, thereby enhancing the mixing efficiency. A completed mixing was achieved in the asymmetric micromixer. (c) 2014 American Institute of Chemical Engineers AIChE J, 61: 1054-1063, 2015