Balloon Lens Design for Enhanced Energy Localization in Catheter-Based Ultrasound Tubular Transducers

Abstract

The piezoelectric tubular transducer presents a promising option for medical applications that involve intraluminal acoustic treatments, such as renal denervation ablation (RDN). These transducers utilize radically polarized piezoelectric ceramics, showcasing an efficient capacity to emit ultrasonic power away from their central axis. This capability facilitates 360° circumferential ablation, thereby improving the procedure's efficiency and effectiveness. However, energy localization is vital for ensuring both safety and efficacy in therapeutic applications. Within the context of vascular interventional procedures, conventional polymer balloons can be designed as low-profile, tubular-shaped lenses. Specifically, Bessel and Fresnel lens configurations hold significant potential for enhancing therapeutic performance. By implementing a periodic and functional distribution of axial binary thickness within the balloons, we have successfully developed both Bessel and Fresnel-type lens setups and evaluated their focusing capabilities and acoustic field distributions using Finite Element Analysis (FEA). The simulation results indicate that these lenses effectively concentrate acoustic energy at a suitable depth of focus. Notably, at an ablation radius of 6 mm, the acoustic pressure increases by 100% to 200%, while the ablation time is reduced from 18 seconds to 14 seconds, a decrease of 22%. These findings have the potential to significantly contribute to improved clinical outcomes.

Note:
Funding declaration: Pudong New Area Science and Technology Development Fund Industry-University-Research Special Program (PKX2024-S13).

Conflict of Interests: The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Keywords: Renal denervation, Catheter-based ultrasound, Ultrasonic lens, Thermal ablation, Bessel beam, Fresnel lens