A Novel Metasurface Design for Generating Needle-Shaped Ultrasonic Beams

In this work, we propose and experimentally demonstrate a metasurface-enabled HIFU strategy that transforms a conventional point-focused ultrasound beam into a needle-shaped focus. Instead of ablating tumors through sequential point-by-point scanning, our approach enables continuous line scanning across the target region, thereby significantly improving treatment efficiency. Numerical simulations and experimental validations confirm that the metasurface can generate a well-confined needle-shaped ultrasonic beams with high acoustic intensity and uniform energy deposition along the needleshaped beams. This needle-shaped HIFU method offers a promising route toward faster, more effective, and clinically practical ultrasound therapies.