Acoustophoretic buffer exchange in microfluidics: quantifying radiation-driven migration, streaming, and flow effects

Area of Science:

• Fluid dynamics
• Acoustofluidics
• Biotechnology

Background:

• Conventional centrifugation for cell processing can be harsh.
• Acoustofluidics offers a gentler, contact-free alternative.
• Buffer exchange performance depends on acoustic forces and fluid flow.

Purpose of the Study:

• Investigate acoustofluidic buffer exchange in a microchannel.
• Characterize particle transport under varying acoustic and flow conditions.
• Validate the method for biological cell processing.

Main Methods:

• Experimental characterization of particle transport in a silicon-glass microchannel.
• Numerical modeling to understand acoustic radiation forces and streaming.
• Biological validation using U2OS and INS-1 pancreatic β-cells.

Main Results:

• Migration velocity shows quadratic dependence on acoustic actuation in no-flow conditions.
• Finite residence time and interface motion impact buffer exchange efficiency.
• Identified operating regimes for efficient particle transfer and buffer preservation.
• Achieved >98% cell viability and improved recovery compared to centrifugation.

Conclusions:

• Acoustofluidic buffer exchange is a viable, gentle cell processing method.
• Optimized operating parameters balance particle transfer and buffer preservation.
• Provides design guidelines for continuous acoustofluidic cell processing systems.