Investigation of the Dynamics of Coupling in Piezoelectric Micromachined Ultrasonic Transducers (PMUTs) Arrays

Piezoelectric Micromachined Ultrasonic Transducers or PMUTs are a technology platform actively being developed for the next generation of ultrasonic medical imaging, non-destructive testing, and power transfer for sensors and Internet of Things applications [1].
PMUT devices are microelectromechanical devices (MEMS) that consist of a suspended circular plate formed by a multi-layer stack of materials which includes a structural layer (typically Silicon or Silicon Nitride), metal electrodes and a piezoelectric material (e.g., PZT, or AlN), as shown in the schematic of Figure 1.a. The application of an electrical signal to the PMUTs causes these structures to vibrate, allowing the observation of the mechanical resonance frequency, as shown in Figure 1.b.

This simplified behaviour from single PMUT resonators take on a more complex form when these PMUTs are placed in large arrays, as is usually required for most applications, and the individual PMUT elements start to interact [2-3].
The proper understanding and quantification of this coupling and its exact dependence on the PMUT array design parameters are the main goals of this internship. As such, this thesis work centres on the simulation, and experimental evaluation of acoustic coupling between PMUT devices. This work will include (but is not limited to), analytical modelling, numerical simulations (e.g. COMSOL), and the experimental testing of PMUT devices/arrays. The internship may also include a component focused on integrating the results into software packages.

References:

[1] Chare, Christopher, et al. "Electromechanical Equivalent Circuit Model for Axisymmetric PMUTs With Elastic Boundary Conditions." Journal of Microelectromechanical Systems (2022).
 
[2] Billen, Margo, et al. "Multi-frequency imaging with a cmos compatible scandium doped aluminum nitride pmut array." 2021 IEEE 34th International Conference on Micro Electro Mechanical Systems (MEMS). IEEE, 2021.
 
[3] Oguz, H. Kagan, Abdullah Atalar, and Hayrettin Köymen. "Equivalent circuit-based analysis of CMUT cell dynamics in arrays." IEEE transactions on ultrasonics, ferroelectrics, and frequency control 60.5 (2013): 1016-1024.

Who are you:
 

• Highly motivated physics or engineering student. Able to work independently.
• Interested in a career in semiconductor technologies, particularly MEMS sensors and actuators.
• You have good programming skills in MATLAB and Python, COMSOL is a plus.
• Comfortable working in a lab environment and good experimental skills.

Type of Project: Internship

Master's degree: Master of Engineering Science 

Master program: Nanoscience & Nanotechnology 

Duration: 6 - 12 months 

Supervisor: Michael Kraft 

For more information or application, please contact the supervising scientist Samer Houri (samer.houri@imec.be).

Only for self-supporting students.