QUANTIFICATION OF ACOUSTIC RADIATION FORCES ON SOLID OBJECTS IN FLUID.

Area of Science:

• Acoustic manipulation
• Radiation force theory
• Ultrasonic transducer technology

Background:

• Theoretical models predict acoustic radiation force for object manipulation.
• Experimental validation of these models is crucial for practical applications.
• Previous work focused on specific beam types and object sizes.

Purpose of the Study:

• To validate a general model of acoustic radiation force on solid objects.
• To quantify lateral force for various beam shapes and object properties.
• To demonstrate electronic steering of large or dense objects using a single-sided transducer.

Main Methods:

• Synthesized vortex and ring-shaped acoustic beams using a 1.5-MHz, 256-element focused array in water.
• Measured and calculated lateral forces on glass, brass, and ceramic spheres (2-6 mm diameter).
• Validated the model by comparing calculated and measured maximum angles for acoustic trapping.

Main Results:

• The validated model showed good agreement (average 22% difference) between calculated and measured forces.
• Maximum lateral force was observed when target diameter matched beam width, but larger objects were also trapped.
• Acoustic forces comparable to gravitational forces were achieved for spheres up to 90 mg at ~10 W beam power.

Conclusions:

• The general acoustic radiation force model is validated for diverse objects and beam shapes.
• Single-sided transducer arrays can electronically steer large or dense objects.
• This research advances acoustic trapping for practical manipulation applications.