Characterization of capacitive micromachined ultrasound transducers

Although ultrasound imaging has been implemented as a powerful diagnostic tool since its discovery in the 1950s, the screening method is still cumbersome. Rigid ultrasound probes have a limited aperture size and must be held at specific angles and pressures to avoid loss of contact and prevent misdiagnosis. A flexible ultrasound patch, that can conform to the skin and image the region of interest without any manual probe repositioning, would therefore significantly improve the reliability of medical imaging. This new technology could also give rise to new applications like continuous cardiac monitoring or muscle screening during exercise.

To create high-density 2D arrays with small pitch requirements, micromachined ultrasound transducers are perfect candidates thanks to their small size, direct integration capability with electronics, and mass-manufacturing compatibility. In this project, the student will perform electrical, mechanical, and acoustical measurements on capacitive micromachined ultrasound transducers (CMUT) fabricated in imec’s cleanroom. It is expected from the student to compare these experimental results with Finite Element Method (FEM) simulations. Combining these results, the student will be able to establish significant guidelines for the rationale design of sensitive capacitive micromachined ultrasound transducers operating at a specific resonance frequency. Depending on the motivation of the student, the research can be further extended to the characterization and simulation of these devices on a curved substrate.