Development of an Advanced Acoustic Isolation system for PMUT array-based imaging

In the field of surgery and interventional medicine, size is a very critical factor. Therefore, MEMS technology, with its micrometer sized machines, is an ideal candidate to solve some of the crucial problems in this field. As catheters evolve and become smaller to allow less invasive procedures, the technology that is integrated with these devices needs to scale down. This research will focus on the use of ultrasound imaging to look in front of the catheter tip to allow better guidance of the catheter into the right direction, lowering risk of damaging the patients' blood vessels. 

Fig 1: conceptual sketch of the prototype.

Classical ultrasound transducers consist of a thick layer of piezo material, sandwiched between two electrodes. Their miniaturized counterparts (PMUTs) allow for a much smaller form factor and easier integration with supporting electronics. They are miniaturized drums containing a piezoelectric layer in their membrane that can generate and pick up mechanical deformation of the suspended membrane. This allows PMUT to emit and receive ultrasound waves by respectively vibrating the membrane or detecting the deformation of the membrane by an incoming wave.

Fig 2: Sketch of PMUT cross-section and working principle.

By using smart arrays of these small transducers, complex ultrasound fields can be generated and received. It is this beamforming feature of arrays of transducers that allows ultrasound imaging. However, a significant limitation for miniaturization and performance for such a system are parasitic acoustic effects, such as device-to-device crosstalk in an array. A development of an advanced acoustic isolation system is required to implement a game-changing precise and miniature acoustic biomedical imaging tool.

The goal of this project is to design, optimize and implement an innovative acoustic isolation system for a PMUT array. This project will give an opportunity to perform an acoustic analysis in solids and fluids, as well as to participate in development of a state-of-the art mechanical structures. Generally, this is a topic for students eager to understand complex systems with a hands on attitude and interest for MEMS devices and multiphysics simulations. High creativity is much appreciated. The work is estimated to be: 50% simulations/calculations (f.e COMSOL, Matlab or likewise), 50% system design.

The broader context of this work is a collaboration between the Robotics team of KU Leuven and the MEMS team of Imec.