Confocal lens focused piezoelectric lithotripter.

Area of Science:

• Biomedical Engineering
• Acoustic Technology
• Medical Devices

Background:

• Development of advanced lithotripters is crucial for minimally invasive kidney stone treatment.
• Piezoelectric lithotripsy offers a promising alternative to existing technologies.
• Optimizing transducer configuration and acoustic focusing is key to improving fragmentation efficiency.

Purpose of the Study:

• To evaluate the performance of a novel piezoelectric lithotripter design.
• To compare acoustic characteristics and in vitro stone fragmentation of 3-transducer and 4-transducer confocal setups.
• To assess the potential of these devices against commercial electroconductive lithotripters.

Main Methods:

• Constructed piezoelectric lithotripters with 3 or 4 large lens-focused 220 kHz transducers in C-shape or spherical confocal arrangements.
• Measured acoustic pressure fields using a fiber optic hydrophone.
• Performed in vitro fragmentation tests on cylindrical model stones using a 2 mm mesh basket.

Main Results:

• The 3-transducer setup produced a disc-shaped focal volume (2.2 x 9.6 mm) with peak pressures of 40.9 MPa (positive) and -16.9 MPa (negative).
• The 4-transducer setup achieved a narrow focus (2.1 mm width) with higher peak pressures of 71.9 MPa (positive) and -24.3 MPa (negative), similar to commercial devices.
• Both configurations exhibited in vitro stone fragmentation efficiency comparable to a commercial electroconductive lithotripter.

Conclusions:

• Novel piezoelectric lithotripter designs with 3 or 4 transducers show significant potential for effective stone fragmentation.
• The 4-transducer setup closely mimics the acoustic focus of traditional high-pressure lithotripters.
• These findings support the viability of piezoelectric technology for advanced lithotripsy applications.