Ultrasonic separation in microfluidic capillaries

We present a new actuator based on glass capillary bonded to laser-cut PZT plate, for ultrasonic control of microparticles inside microfluidic channels. The actuator generates high velocity bending mode at low CMOS compatible 5-10 Vpp drive. The high velocity enables focusing of samples at the nodes and the antinodes of the bending waves in the capillary. Separation of 3 and 10 microns polystyrene microbeads in space by 800 μm is achieved. E. Coli cells and blood cells can also be separated with particles with lower density than water being placed at the transverse velocity nodes and heavier particles at the antinodes.