Ultrasonic focusing with mesoscale polymer cuboid

Area of Science:

• Acoustics
• Materials Science
• Optics

Background:

• Geometrical Optics typically dictates specific conditions for sound focusing.
• Mesoscale polymer structures offer potential for novel acoustic applications.
• Negative refraction is often considered essential for acoustic lensing.

Purpose of the Study:

• To demonstrate sound focusing using flat polymer mesoscale cuboids without negative refraction.
• To compare the acoustic lens performance of PMMA and Rexolite®.
• To determine conditions for achieving sub-diffraction acoustic focal spots.

Main Methods:

• Numerical simulations using the Finite Element Method (FEM).
• Experimental validation of acoustic wave focusing.
• Comparison of acoustic pressures and focal distances between simulation and experiment.

Main Results:

• Flat polymer cuboids can focus sound, contradicting traditional Geometrical Optics.
• Rexolite® was identified as a preferable material for acoustic jet formation.
• A single localized focal region with sub-diffraction transverse size (approx. 0.44 wavelength) was achieved.
• FEM numerical results showed fair agreement with experimental findings.

Conclusions:

• Mesoscale polymer cuboids offer a viable alternative for acoustic focusing.
• The study provides a foundation for designing advanced acoustic lenses.
• The findings open new avenues for acoustic manipulation and imaging technologies.