A simple acoustofluidic chip for microscale manipulation using evanescent Scholte waves.

Area of Science:

• Acoustofluidics
• Surface Acoustic Waves
• Biophysics

Background:

• Acoustofluidics utilizes acoustic waves for contactless manipulation of micro-objects.
• Existing methods often rely on propagating acoustic waves in standing or progressive fields.
• There is a need for novel acoustofluidic techniques with enhanced surface confinement and efficiency.

Purpose of the Study:

• To introduce and characterize a new acoustofluidic approach using evanescent acoustic fields.
• To demonstrate the generation and properties of quasi-Scholte acoustic waves for microfluidic applications.
• To showcase the utility of this method in cell patterning, manipulation, and blood component separation.

Main Methods:

• Generation of an evanescent acoustic field via subsonic interfacial waves.
• Imaging and probing of the evanescent acoustic field to identify quasi-Scholte acoustic waves.
• Development of a simple, low-cost device for acoustofluidic applications.

Main Results:

• Identified interfacial waves as quasi-Scholte acoustic waves, a type of guided wave.
• Demonstrated that these waves confine acoustic energy near the surface and propagate with minimal loss.
• Showcased applications including cell patterning, cell spinning, and plasma separation from blood.

Conclusions:

• Quasi-Scholte acoustic waves offer a powerful, label-free, and contactless method for acoustofluidics.
• The developed technique is versatile, efficient, and applicable to various biological and microfluidic manipulations.
• This approach provides a low-cost and effective platform for advanced acoustofluidic applications.