Microfluidic mixer having channel width variation for enhanced fluid mixing

A micromixing apparatus, comprising:

• a substrate having a top surface;
• a mixing microchannel formed in said top surface of said substrate having a channel length and a continuously variable channel width along said channel length defined by a first sidewall surface and an opposing second sidewall surface, wherein said continuously variable channel width continuously varies from a minimum channel width h to a maximum channel width H in a ratio of H:h≧1.1:1.0, and
• a first inlet for injecting a first fluid into said mixing microchannel and a second inlet for injecting a second fluid into said mixing microchannel, wherein said first and said second fluid flow in a flow direction in said mixing microchannel along said channel length, and
• wherein said first sidewall surface includes a plurality of first curved surface portions and said second sidewall surface includes a plurality of second curved surface portions, said plurality of first curved surface portions and said plurality of second curved surface portions non-overlapping by being offset with respect to one another along said channel length to provide said continuously variable channel width.