Modulating ultrasound field phase and amplitude using foam gratings as an alternative to acoustic lenses

• Published in: The Journal of the Acoustical Society of America 2024-03, Vol.155 (3_Supplement), p.A139-A139
• Main Authors: Richards, Luke A., Stride, Eleanor P., Cleveland, Robin O.
• Format: Article
• Language: English
• ISSN: 0001-4966; 1520-8524
• DOI: 10.1121/10.0027083

There is an increasing number of applications for therapeutic ultrasound, including high intensity focused ultrasound surgery, neuromodulation and drug delivery. For many of these applications, accurate focusing of the ultrasound field at tissue depths of several cm is essential and thus patient-specific acoustic lenses have been widely investigated as an economical alternative to phased array transducers. Lenses can be cast or 3D printed from a range of polymers offering good acoustic impedance matching to human tissue. Disadvantages of polymer lenses, however, include their relatively large size and the difficulties involved in eliminating gas bubbles during production. In this study an alternative approach is investigated using a “grating” comprising a sheet of polymer foam, perforated with a series of pores that act as wave guides. The grating is placed in front of a transducer with the pores arranged to modulate the phase and amplitude of the sound field as required. The gratings can be cheaply and rapidly fabricated, are