Active microfluidic mixer and gas bubble filter driven by thermal bubble micropump

A microfluidic mixer with a gas bubble filter activated by a thermal bubble actuated nozzle-diffuser micropump is successfully demonstrated. The oscillatory flow generated by the micropump can induce wavy interface to increase the contact area of mixing fluids to accelerate the mixing process. The microfluidic mixing channels are 200 mum wide, 50 mum deep and the speed of the mixing liquids are measured at 6.5 mul/min. The optimal mixing result is found when the actuating frequency of thermal bubble reaches 200 Hz. Normalized gray-scale values that correspond to the completeness of the mixing effect are observed to be proportional to the one-third power of the input pulse frequency. Furthermore, a gas bubble filter is integrated and successfully demonstrated in the microfluidic mixing system. A model based on the principle of threshold pressure with respect to the geometry of microchannels is established. (C) 2002 Published by Elsevier Science B.V.