[2025] High-Acoustic Transmissivity in Miniaturized Ultrasonic Phased Array Transducers

Traditional ultrasound imaging transducers typically incorporate backing layers to
reduce acoustic ringing and control bandwidth. While this approach helps improve
signal clarity, the backing materials often introduce acoustic losses that lower
transmission efficiency [1]. In contrast, using less absorbent or highly reflective
materials (such as air-backing or low-impedance polymers) can significantly
enhance forward acoustic transmission, leading to greater transducer efficiency.
This improvement has particular importance in applications like implantable and wearable 
neurostimulation, ultrasound imaging, and therapeutic ultrasound, since it can improve power efficiency and enable battery-powered operation..
However, conventional therapeutic ultrasound probes are generally single-
element, low-frequency devices featuring bulky designs, where air-backing layers
are easier to integrate[2]. The focus of this project is to miniaturize and improve
high-frequency phased-array transducers by adopting low-absorption backing
layers on each piezoelectric (PZT) element. Such an approach not only enhances
acoustic transmission but also improves the power efficiency of ultrasound micro-
devices, enabling longer operation if battery-powered[3].
 

[1] C. Chen et al., “A prototype PZT matrix transducer with low-power integrated
receive ASIC for 3-D transesophageal echocardiography,” IEEE Trans Ultrason
Ferroelectr Freq Control, vol. 63, no. 1, pp. 47–59, Jan. 2016, doi:
10.1109/TUFFC.2015.2496580.
[2] H. S. Gougheri, A. Dangi, S. R. Kothapalli, and M. Kiani, “A Comprehensive
Study of Ultrasound Transducer Characteristics in Microscopic Ultrasound
Neuromodulation,” IEEE Trans Biomed Circuits Syst, vol. 13, no. 5, pp. 835–
847, Oct. 2019, doi: 10.1109/TBCAS.2019.2922027.
[3] G. K. Wardhana, M. Mastrangeli, and T. L. Costa, “Maximization of Transmitted
Acoustic Intensity from Silicon Integrated Piezoelectric Ultrasound
Transducers,” in IEEE International Ultrasonics Symposium, IUS, IEEE
Computer Society, 2022. doi: 10.1109/IUS54386.2022.9957646.

Assignment

1. Literature review on ultrasound transmitters and COMSOL modelling to
optimize design parameters to maximize acoustic output.
2. Fabrication of less-absorbent material at the rear end of each PZT
transducers and perform experimental testing to characterize and validate
improvements in acoustic performance and power-efficiency.

Requirements

MSc students from Microelectronics, Biomedical Engineering, Mechanical
Engineering or Applied Physics. Prior knowledge on COMSOL is preferred.
Interested students should include their CV, the list of courses attended, and a
motivation letter, and send it to Tiago Costa (t.m.l.dacosta@tudelft.nl) and Eshani
Sarkar (E.Sarkar@tudelft.nl).

Contact

Last modified: 2025-02-28