Optimization and implementation of intravascular ultrasound (IVUS) imaging system on catheter with PMUT array
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. Catheters play a big role in minimal invasive procedures where they are for example used to fix damaged blood vessels. Nowadays, there are typically two methods to image the blood vessel at the catheter tip, being optical coherence tomography and ultrasound imaging. The first, has the advantage of currently providing higher resolution compared to its ultrasonic counterpart but the disadvantage of needing to flush away the blood in front of the catheter to free the optical path. In the big blood vessels such as the aorta, however, it is impossible to flush the blood. Therefore, this research focuses on development of an ultrasound imaging system to look in front of the catheter tip (forward looking IVUS) to lower the risk of damaging patients' blood vessels when performing procedures in the aorta and heart.
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. A PMUT works on the principle of vibration of a membrane. These miniaturized drums contain a piezoelectric layer in their membrane that can generate and pick up mechanical deformation of the suspended membrane by applying or receiving an electrical signal over the piezoelectric layer. 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 1: Sketch of PMUT cross-section and working principle.
By using smart arrays of these small transducers and controlling electrically them in an organized manner, complex ultrasound fields can be generated and received. It is this beamforming feature of arrays of transducers that is at the base of ultrasound imaging.
In this work, the goal is to optimize and implement a forward-looking intravascular ultrasound system based on a PMUT array. The optimization can concern the ultrasound array (individual transducer design, array configuration, ...), the electronic system (connectivity towards sample, PCB design, ...) and imaging data analysis. Depending on the students' interest, the balance between simulations and experimental work will be steered. Generally, this is a perfect topic for students eager to understand complex systems with a hands-on attitude and interest for MEMS devices. The work is estimated to be: 40% simulations/calculations (f.e COMSOL, Matlab or likewise), 30% characterization, 30% hardware design and implementation. Furthermore, this gives you the opportunity to work on cutting edge innovative technology in an application oriented project.
Fig 2: conceptual sketch of the prototype.
The broader context of this work is a collaboration between the MEMS team of Imec and the Robot-Assisted Surgery Research Group within department of Mechanical engineering of KU Leuven.
Type of project: Thesis
Duration: 6-12 months
Required degree: Master of Engineering Technology, Master of Engineering Science, Master of Science
Required background: Mechanical Engineering, Biomedical engineering, Nanoscience & Nanotechnology, Physics, Electromechanical engineering, Electrotechnics/Electrical Engineering