Micro Mixer Based on Surface Acoustic Wave Driving

A resonance frequency of 8.9MHz copper Interdigital Transducer (IDT) is fabricated on a 127.8 degrees YX type LiNbO3 substrate by lift-off process and the rapid droplet mixing is experimentally realized using the surface acoustic wave (SAW). The droplet mixing principle and the manufacturing process of the mixer are illustrated in detail. The droplet generates one swirl when only portion of the droplet is located on the saw propagating surface. The droplet generates two swirls when the whole of droplet is located on the saw propagating surface. The mixing between red particles with an average diameter of 1.5 mu m and a droplet with a volume of 3 mu 1 is successfully implemented. No matter the droplet covers whole or just partly the saw propagating surface, the mixing process can be completed in one second when the applied driving power is 9W. The applications of SAW micro fluidics should be greatly enhanced using the rapid mixing process proposed in this paper.