Development of a compact self-focusing piezoelectric generator using electrical pre-strain piezocomposite material

Area of Science:

• Biomedical Engineering
• Materials Science
• Acoustics

Background:

• Lithotripsy requires smaller shock heads for clinical applications.
• Existing piezoelectric shock head designs face limitations in increasing surface pressure for high-frequency transducers.
• Mechanical pre-stressing methods are unsuitable for high-frequency (0.5 MHz) operation.

Purpose of the Study:

• To propose and validate a novel electrical pre-straining method for piezoelectric materials.
• To enhance the surface pressure generation of piezoelectric transducers for lithotripsy.
• To develop a compact and efficient shock wave generator for medical applications.

Main Methods:

• Electrically pre-straining piezoelectric material using a high electric field opposite to polarization.
• Investigating three modes: continuous pre-strain, short-duration pre-strain before pulsing, and re-poling between pulses.
• Designing and testing a compact shock wave generator using 1-3 piezocomposite material.

Main Results:

• The re-poling method increased maximum surface pressure by 20% to 4 MPa on a 20 mm piston.
• A compact generator (120 mm diameter, 120 mm focus) achieved 60 MPa maximum pressure with a 1.5 microsecond compressive wave.
• The generator disintegrated 15 mm plaster balls in 150 shocks, comparable to electrohydraulic lithotripters.

Conclusions:

• Electrical pre-straining, particularly re-poling between pulses, effectively enhances piezoelectric transducer performance.
• The developed piezoelectric shock wave generator is compact, efficient, and comparable to established lithotripsy technologies.
• Piezoelectric materials offer a viable alternative for manufacturing advanced shock wave generators for lithotripsy.