Acoustic mixing and chromatography in a PZT driven silicon microfluidic actuator

An ultrasonically driven silicon bulk microfabricated microfluidic actuator for the manipulation of microparticles suspended in a fluid is presented. The major advantage of the device is enabling of multiple particle manipulation capabilities such as collection, separation and mixing, on a single bulk-PZT-silicon platform at low drive voltages (1-10 Vpp). Different types of vibrational modes generated on the silicon body and the silicon nitride membrane generates frequency addressable differential acoustic traps. While high amplitude membrane modes remain in the subsonic regime and generate boundary streaming effects, modes in the silicon body are supersonic and can generate acoustic pressure gradients in the cavity. This architecture enables a battery operated, portable, microfluidic sensor and actuator device for microbiological and colloidal applications.