Public defence in Biomedical Engineering, M.Sc. Emanuele Perra
Opponent: Professor Michael R. Bailey, University of Washington, USA
Custos: Professor Heikki Nieminen, Aalto University School of Science, Department of Neuroscience and Biomedical Engineering
Contact details of the doctoral student: [email protected], +358 505135200
The defence will be organized on campus and in Zoom (Otakaari 4, lecture hall 213a, link to the event).
The doctoral thesis will be publicly displayed 10 days before the defence in the publication archive of Aalto University.
Ultrasound can extend the applications of medical needles, suggests a doctoral thesis.
The subject of this Thesis deals with the use of ultrasound to induce oscillations in a standard medical needle to provide new medical functions. This research was motivated by the lack of important technological improvement that medical needles have faced in the last 150 years. For this reason, medical needles still present limitations regarding pain, precision, spatial localization and, in the context of needle biopsies, inadequacy of the tissue yield. In light of this, the goal of this research was to explore if nonlinear ultrasound can be used to provide new functions to medical needles, while addressing their major limitations.
In this research, the behavior of medical needles oscillating at the frequency of 30 kHz was studied. This resulted in obtaining amplification of the acoustic energy towards the needle tip, which revealed to be particularly useful. In fact, the synergistic action of the sharp edges of the needle tip, mainly responsible for mechanical shear and cutting of the surrounding tissue, and the provided ultrasound emission from the needle into tissue, can contribute to influencing soft tissue beyond the capabilities of a standard medical needle. With numerical and experimental methods, it was demonstrated that the oscillations of the needle induced the generation of several nonlinear acoustic phenomena, namely, cavitation (sudden expansion and collapse of air bubbles), acoustic streaming (generation of acoustically driven fluid flows), acoustic radiation force (force exerted on an object by an ultrasound wave) and atomization (ejection of micro-droplets from liquid surface), potentially useful in addressing medical needs in new ways.
In the context of the fine-needle aspiration biopsy procedure, it was exemplified how the ultrasonic actuation of the needle can increase the amount of collected tissue up to 6x, as compared to the one obtained with a standard procedure using the same needle. This result is of special importance for cancer management because this approach could mitigate the main limitations associated with the insufficiency of extracted tissue, which can lead to inconclusive diagnoses and re-biopsies. The investigated approach has the potential to give conventional medical needles new enhanced functions in medical applications beyond tissue biopsy, e.g. to drug or gene delivery, cell modulation, and minimally invasive surgical procedures.