Microfluidic sub-millisecond mixers for the study of chemical reaction kinetics

We present a micromachined, high Reynolds number (2000-6000), sub-millisecond liquid mixer for the study of chemical reaction kinetics. This 1 cm/spl times/1 cm/spl times/1 mm bulk micromachined silicon mixer is capable of initiating and quenching (starting and stopping) chemical reactions in intervals as short as 100 /spl mu/s. The centimeter sized mixer chip contains two tee mixers connected by one channel which serves as a reaction chamber. Each tee mixer consists of opposing channels where liquids meet head-on and exit into a third channel forming the base of a "T". Our mixer performance was characterized by employing two carefully chosen chemical reactions with reaction time constants of 3 ms and 9 ms along with visualization techniques using dyes and acid-base indicators.