Structural Optimization and Simulation of Dual-Frequency Piezoelectric Micromachined Ultrasonic Transducers

Area of Science:

• Materials Science
• Acoustics
• Biomedical Engineering

Background:

• Ultrasound transducers are critical for medical imaging, but balancing bandwidth and sensitivity is a design challenge.
• Piezoelectric micromachined ultrasound transducers (PMUTs) are essential components, with dual-frequency designs offering versatility.
• Optimizing transducer performance, particularly bandwidth and sensitivity, is key for advanced medical imaging.

Purpose of the Study:

• To optimize the backing layer of a dual-frequency PMUT using polydimethylsiloxane (PDMS).
• To investigate the impact of PDMS backing layer thickness and geometry on PMUT performance.
• To enhance bandwidth and sensitivity for improved ultrasound imaging applications.

Main Methods:

• Finite element simulations using COMSOL multi-physics version 6.2.
• Equivalent circuit modeling to analyze frequency response and impedance matching.
• Experimental investigation of PDMS backing layer effects on acoustic sensitivity.

Main Results:

• Optimized PMUT structure achieved a 92% -6 dB bandwidth at 2.3 MHz and 6.8 MHz.
• PDMS backing layer improved impedance matching for low- and high-frequency signals.
• Enhanced sensitivity and reduced interface reflection losses were observed with the PDMS layer.

Conclusions:

• Polydimethylsiloxane (PDMS) effectively expands the operational bandwidth of dual-frequency PMUTs.
• The optimized PMUT design maintains high sensitivity while achieving broader bandwidth.
• This research offers potential for high-performance ultrasound imaging, especially for deep penetration and high-resolution medical needs.