Piezoelectric actuators for acoustic mixing in microfluidic devices—Numerical prediction and experimental validation of heat and mass transport

• Acoustic streaming is proposed to speed up mixing of fluids.
• PZT and β-PVDF piezoelectric materials are explored for integration in microdevices.
• Numerical simulations and experimental tests showed flow vortices and mixing time reduction.
• The temperature of the system increased, which can be advantageous for heating applications.
• The results showed agreement between simulations and experimental tests, useful for predicting new materials behavior.

Microfluidic devices have been used for handling and analyzing micro scale fluidic quantities with small concentrations, relying on smaller devices, with increased portability and availability. This paper proposes a solution to reduce the mixing time required in microfluidic devices analyses, without the need of pumps or moving parts. To speed up the required mixing, acoustic streaming is proposed. Two different piezoelectric materials, PZT and β-PVDF, are explored, concerning their actuation frequencies, for integration in microfluidic devices. Their layout, actuation frequency and behavior were compared for mixing two fluids inside a microfluidic reaction chamber. Numerical simulations and experimental tests showed flow vortices generation and a significant mixing time reduction for both materials: above 90% for PZT and above 80% for β-PVDF. It was also observed an increase of the temperature on the transducers surface, which is advantageous for applications in which heating is necessary. The results showed agreement between simulations and experimental tests which can be useful for predicting new materials behavior for improving microfluidic devices mixing.