PMUT array for vertebra 3D imaging

PMUT array for vertebra 3D imaging

Master projects/internships - Leuven

Wearable ultrasonic imaging devices for human health monitoring

MEMS technology, with its micrometer feature sized devices, is an ideal candidate to solve some of the crucial problems in wearable devices for human health monitoring. Ultrasonic imaging devices play a critical role in in vitro human health monitoring. Wearable ultrasonic arrays can do imaging to monitoring bone kinetics, vessel pulsation, lung conditions and so on. Compared with other imaging modalities, ultrasound has the advantage of non-radiative, non-invasive and capability of realizing real time dynamic imaging. This research will focus on prototyping an ultrasound imaging system, which can be attached on the lower back of human body to generate 3D imaging of lumbar vertebra and use the biomarkers from the image to diagnose the low back pain disease, which is pervasive among aged population.

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.

The goal of this thesis is to prototype a PMUT-based imaging device and demonstrate using it to do 3D imaging on the lumbar vertebra. The candidate will characterize the acoustic transmission of the PMUT and design PCB connecting the PMUT to the imaging control setup. The candidate will do signal processing of the acquired data and reconstruct 3D imaging based on the data. The reconstructed surface profile will be registered on the vertebra ground truth model to verify the imaging accuracy. Depending on the students' interest, the balance between experimental work and signal processing will be steered. Generally, this is a perfect topic for students eager to understand ultrasonic imaging with a hands-on attitude and interest for MEMS devices. The work is estimated to be: 40% signal processing (f.e Matlab or Python), 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.

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Fig 2: (a) PMUT layout; (b) schematic showing doing imaging on the vertebra.

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

Master's degree: Master of Engineering Technology, Master of Engineering Science, Master of Science

KU Leuven promoter: Associate Prof. Emmanuel Vander Poorten

Master program: Mechanical Engineering, Biomedical engineering, Nanoscience & Nanotechnology, Physics, Electromechanical engineering, Electrotechnics/Electrical Engineering

Duration: 6-12 months

For further information or for application, please contact Dr. Zhiyuan Shen Zhiyuan.Shen@imec.be