A single-element transducer with nonuniform thickness for high-frequency broadband applications

Area of Science:

• Ultrasound transducer technology
• Piezoelectric materials
• Acoustic engineering

Background:

• Conventional single-element transducers (SEUTs) have limitations in frequency range.
• Broadband transducers are crucial for advanced imaging modalities like harmonic imaging.
• Lithium niobate (LiNbO3) is a common piezoelectric material for high-frequency applications.

Purpose of the Study:

• To design, fabricate, and evaluate a high-frequency single-element annular transducer (SEAT).
• To compare the performance characteristics of the SEAT with a conventional SEUT.
• To assess the suitability of the SEAT for imaging applications requiring wider bandwidths.

Main Methods:

• Fabrication of a SEAT using 36 degrees-rotated, Y-cut LiNbO3 with varying thickness (60-110 microm).
• Utilized ultrasonic sculpturing for annular pattern creation, achieving surface roughness of 454.47 nm.
• Evaluated transducer characteristics including bandwidth, insertion loss, and acoustic beam pattern via simulations and experiments.

Main Results:

• The SEAT demonstrated a 19% larger bandwidth compared to the SEUT.
• A 2-way insertion loss increase of 3.1 dB was observed for the SEAT versus the SEUT.
• Finite-element simulations and experimental analysis showed good agreement for the acoustic beam pattern, with a -6 dB beam width of 108 microm at focus.

Conclusions:

• The SEAT provides a significantly broader frequency range, enhancing its utility for advanced ultrasound imaging.
• Despite increased insertion loss, the SEAT's wider bandwidth makes it suitable for applications such as harmonic imaging.
• The SEAT can be manufactured using established techniques for multi-frequency band transducers.