Double aperture focusing transducer for controlling microparticle motions in trapezoidal microchannels with surface acoustic waves

We present a method for controlling the motion of microparticles suspended in an aqueous solution, which fills in a microchannel fabricated into a piezoelectric substrate, using propagating surface acoustic waves. The cross-sectional shape of this microchannel is trapezoidal, preventing the formation of acoustic standing waves across the channel width and therefore allowing the steering of microparticles. The induced acoustic streaming transports these particles to eliminate the use of external pumps for fluid actuation. (C) 2009 American Institute of Physics. [doi: 10.1063/1.3238313]