Amplification of Acoustic Forces Using Microbubble Arrays Enables Manipulation of Centimeter-Scale Objects

Area of Science:

• Acoustic manipulation
• Fluid dynamics
• Microscale and macroscale physics

Background:

• Acoustic manipulation of macroscale objects is typically constrained by the wavelength of sound and the object's size.
• While resonant subwavelength scatterers like bubbles can mitigate these constraints, they usually exert weak forces.

Purpose of the Study:

• To investigate if patterning bubbles into arrays can amplify acoustic scattering forces.
• To demonstrate the precise assembly and manipulation of centimeter-scale objects using enhanced acoustic forces.

Main Methods:

• Creation of patterned arrays of resonant subwavelength scatterers (bubbles).
• Application of acoustic waves with a long wavelength (50 cm) to manipulate centimeter-scale objects.
• Utilizing secondary Bjerknes forces for manipulation.

Main Results:

• Geometric amplification of acoustic scattering forces was achieved through bubble patterning.
• Continuous rotation and precise positioning (15 μm accuracy) of a 1 cm object were demonstrated.
• Experimental results were accurately described by a theoretical model.

Conclusions:

• Patterned bubble arrays significantly enhance acoustic forces for object manipulation.
• This method decouples object size and sound wavelength limitations in acoustic manipulation.
• The findings provide a foundation for controlled organization and manipulation of macroscale structures using acoustic forces.