Design and Structure of a Non-Coaxial Multi-Focal Composite Fresnel Acoustic Lens for Synergistic Ultrasound Stimulation of Multiple Brain Regions.

Authors: Wu R, Shi F, Tao J, Zhao J, Zhang J, Wu X, Xu J

Transcranial focused ultrasound (TcFUS) neuromodulation is hindered by skull-induced acoustic limitations. To enable synergistic multi-region brain stimulation, we designed non-coaxial multi-focal composite Fresnel acoustic lenses, including an overlapping Fresnel lens (OFL) and an alternating-segmented Fresnel lens (ASFL). These lenses convert planar ultrasound into multiple foci. Based on Fresnel theory, acoustic fields were analyzed via simulations and experiments, validating the generation of four non-coaxial foci (10/30 mm focal lengths) from a 1 MHz planar wave using both OFL and ASFL. The influence of lens parameters on focal pressure distribution was investigated, and morphology was quantified using a linear least-squares method. Significant differences in focal morphology and intensity between OFL and ASFL provide crucial guidance for optimizing multi-target TcFUS strategies.

Introduction

Purpose Transcranial ultrasound stimulation

Study Objective Design and validate non-coaxial multi-focal composite Fresnel acoustic lenses (OFL and ASFL) to enable multi-region transcranial focused ultrasound neuromodulation by converting planar ultrasound into multiple foci.

Animal model / Human subject skull mimic

Outcomes and Safety

Summary of Outcomes No biological or behavioral effects were reported; the study demonstrated that overlapping Fresnel lens (OFL) and alternating-segmented Fresnel lens (ASFL) converted a 1 MHz planar ultrasound into four non-coaxial focal spots (focal lengths 10 mm and 30 mm), with significant differences in focal morphology and intensity between lens types.

Safety-related matter No safety issues or adverse effects were reported or discussed in the provided text; the paper focuses on lens design, simulations, and experimental validation of multi-focal acoustic fields.

Brain Region

Visualization unavailable

Ultrasound Parameters

FUS Frequency 1 MHz

Focal Characteristics Focal depth: None; Focal length: 10 mm, 30 mm; Aperture size: None

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