Reconfigurable liquid-based acoustic lens for controlling the focal depth of focused ultrasound
Year: 2026
Type: article
Abstract: Focused ultrasound (FUS) enables noninvasive treatment. Conventional FUS transducers with fixed geometries lack depth control, whereas dynamic focusing with multi-element phased arrays requires complex electronics that limit scalability. This study introduces a reconfigurable, liquid-based acoustic lens that attaches to a single-element planar ultrasound transducer to provide tunable focal-depth control. The lens consisted of a deformable low-density polyethylene membrane filled with perfluorooctyl bromide (PFOB), a biocompatible liquid with matching acoustic impedance and low reflectivity, and was coupled to a 500-kHz transducer. Adjusting the internal PFOB volume changed the lens curvature and acoustic wavefront, thereby controlling focal depth. Acoustic pressure fields were mapped under three conditions: no lens, 2 mL PFOB, and 3 mL PFOB. Cross-sectional analysis showed volume-dependent plano-convex lens deformation, with central heights of approximately 3.6 mm and 4.7 mm at 2 mL and 3 mL, respectively. Acoustic field maps showed that increasing the PFOB volume shortened the focal depth from 52 mm without a lens to 37 mm and 26 mm, with improved focal localization. Numerical simulations closely reproduced the experimental pressure maps. These findings demonstrate controllable focusing with a reconfigurable, liquid-based acoustic lens in a compact, single-element FUS system.
Source: ULTRASONOGRAPHY
DOI: 10.14366/usg.26174
Language: English
Subfield: Biomedical Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: diamond
OpenAlex ID: W7223707945