Focusing Ultrasound with Acoustic Metamaterial Network

TL;DR

This paper demonstrates the first experimental focusing of ultrasound waves using a flat acoustic metamaterial lens made of subwavelength Helmholtz resonators, achieving a tight focus and variable focal length.

Contribution

It introduces a novel flat acoustic metamaterial lens with subwavelength resonators, enabling ultrasound focusing and variable focal length, validated by experiments and simulations.

Findings

Achieved a half-wavelength focus at 60.5 KHz

Lens exhibits variable focal length at different frequencies

Experimental results match numerical simulations

Abstract

We present the first experimental demonstration of focusing ultrasound waves through a flat acoustic metamaterial lens composed of a planar network of subwavelength Helmholtz resonators. We observed a tight focus of half-wavelength in width at 60.5 KHz by imaging a point source. This result is in excellent agreement with the numerical simulation by transmission line model in which we derived the effective mass density and compressibility. This metamaterial lens also displays variable focal length at different frequencies. Our experiment shows the promise of designing compact and light-weight ultrasound imaging elements.