Micro mixer using turbulence principle was first reported. The turbulence occurred from the work of valveless micropump. Liquids were mixed in a chamber with oscillating diaphragm driven by PZT at high frequency. The mixer had a layout of 2 pairs of diffusers on the inlet and outlet of the chamber, respectively. All those diffusers were in the size of 1.5 mm long and had an angle of 5°. The diaphragm was in the size of 6 mm x 6 mm x 0.15 mm. The mixing chamber was in the same length and width of diaphragm and had a depth of 0.04 mm. A piece of bulk PZT (5 mm × 4 mm × 0.2 mm) was glued onto the diaphragm. As a pump, it worked until 10 kHz when a square wave voltage (120V peak-to-peak) was used for the excitation. The maximum output was found to be 15.6 μl/min of the maximum flow rate and 2.16 kPa of the zero flow pressure using 870 Hz square excitation wave to drive ethanol. To test the properties of the mixer, different pigments were added into water, methanol and ethanol, respectively. The color changes were observed when water mixed with ethanol and methanol mixed with ethanol.
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