Particle positioning in microchannels using ultrasonic standing waves reinforced with radiated near and far field pressure waves

This paper describes our continuing work in using ultrasonic standing waves to manipulate particles in microfluidic channels. Here, we present our work in creating microfluidic channels for particle routing and planar piezoelectric PZT transducers for particle focusing. Near field pressure is used to “reinforce” the standing wave node at the center of a glass microfluidic channel and is shown to improve the focusing capabilities. Moreover, the design is compatible with future designs that use multiple piezoelectric transducers for phased three-dimensional particle manipulation in microfluidic channels.