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Ultrasound Waveform Optimization for Power Efficient Focused Ultrasound Neuromodulation
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Resumo(s)
Ultrasound neuromodulation is a promising ultrasound modality since it combines high spatial
resolution and high coverage of the brain while remaining minimally invasive. It is performed by
exciting a transducer with an alternating pulse signal at its resonance frequency. These pulse signals are
typically sent in bursts. The piezoelectric transducer converts this signal into an acoustic wave, resulting
in multiple acoustic waves within each burst. Bulk ceramic piezoelectric transducers have a high-quality
factor, meaning that for a single pulse excitation, it produces several pulses with decaying amplitude.
The main goal of this dissertation was to explore potential power savings in the ultrasound transmitter
by removing pulses from a long burst of pulses and bursts from the neuromodulation cycle while
minimizing the decay of the acoustic wave amplitude. This goal was accomplished by developing an
experimental setup for ultrasound stimulation using two different transducers: High-Intensity Focused
Ultrasound and Air-Backing transducers. In this study, it was also simulated two different approaches:
removing pulses by short and open circuits.
The results showed that using the Air-Backing transducer, it’s possible to save more energy than with
the other transducer. The simulations from the Air-Backing transducer, in which only a percentage of
the pulse amplitude was removed, showed better results than the total removal of the pulses, and among
the results presented, the 30% amplitude removal is the case with the highest efficiency.
Another comparison made in this project suggests that performing pulse removal through a short circuit
generates very positive results while performing pulse removal through an open circuit was not
beneficial to the hypothesis under study.
Future work to be done should include experiments and simulations with neurons since the behavior of
ultrasound in neurons is still not fully understood, and the obtained results may prove to be quite
different from the simulations.
Descrição
Tese de mestrado, Engenharia Biomédica e Biofísica, 2023, Universidade de Lisboa, Faculdade de Ciências
Palavras-chave
Ultrassons Neuromodulação Ultrassónica Não Invasivo Remoção de Pulso Teses de mestrado - 2023