Effective Acoustic Field Generation in Disposable Dispensing Cartridges for Acoustophoretic Particle Focusin

This paper deals with acoustophoretic particle focusing and its application to single-cell dispensing. Building on previous work, significant progress was achieved: 1) Effective acoustic field generation inside a microfluidic chip of a dispensing cartridge by a detachable piezoelectric actuator was successfully shown. This enables acoustophoretic focusing of particles prior to the nozzle of the single-use dispensing cartridge and ensures the reusability of the piezoelectric transducer. The frequency at which fluidic resonance occurs remains constant for several cartridges. 2) It was demonstrated by admittance measurements that the resonance spectrum of the piezoelectric actuator is largely independent of the dispensing cartridge. Additionally, measurement of chip vibrations and particle image velocimetry (PIV) were used to characterize the system. This allows for estimation of the particle focusing velocity for a specific system at different actuation frequencies. 3) Acoustophoretic focusing by the detachable actuator was shown to positively affect dispensing speed and bead loss compared to single-cell dispensing without focusing.