A cross beam ultrasound neurostimulation setup based on two 128-element sparse matrix arrays

Low Intensity Focused Ultrasound (LIFU) presents a promising non-invasive alternative for brain stimulation, offering precise targeting of deep brain structures. This study explores the development of a cross-beam matrix-array based ultrasound neurostimulation setup aimed at improving spatial resolution in the axial dimension. We identified an optimized 128-element sparse array configuration that maintains field metrics comparable to a fully populated 256-element array in a simulation study and manufactured corresponding arrays. The study investigates cross-beam focusing capabilities using a dual array configuration, addressing challenges related to sonication planning and phase aberration correction (PAC) for accurate excitation delays. Experimental validation demonstrated successful cross-beam focusing through an ex-vivo human skull model, revealing minimal distortion in pressure fields and enhancements in focus pressure of up to 15% when employing PAC delays. Our findings underscore the potential of sparse matrix arrays and cross-beam setups to refine ultrasound neurostimulation techniques, paving the way for future evaluations in more complex anatomical models.