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Thermal Acoustic Flow inside an Ultrasound Resonator

Corato, Enrico LU (2020) BMEM01 20202
Department of Biomedical Engineering
Abstract
This thesis aims at investigating the interaction between thermal gradients and acoustic fields in microfluidic devices. In the research branch of Acoustofluidics, which bridges together acoustics and fluid dynamics, inhomogeneity in the medium has gained great interest due to the novel physics behind and the potential in manipulating submicrometer particles. Concentration gradients of solute molecules have already been proven in previous studies to be effective means to obtain differences in fluid properties, such as density and compressibility, which induce acoustic body force and heavily affect the acoustic streaming. In this project another approach was taken, i.e. generating the inhomogeneity by thermal fields, to achieve a more... (More)
This thesis aims at investigating the interaction between thermal gradients and acoustic fields in microfluidic devices. In the research branch of Acoustofluidics, which bridges together acoustics and fluid dynamics, inhomogeneity in the medium has gained great interest due to the novel physics behind and the potential in manipulating submicrometer particles. Concentration gradients of solute molecules have already been proven in previous studies to be effective means to obtain differences in fluid properties, such as density and compressibility, which induce acoustic body force and heavily affect the acoustic streaming. In this project another approach was taken, i.e. generating the inhomogeneity by thermal fields, to achieve a more stable and smooth variation in the thermophysical properties of the medium across the microchannel.
The thesis work developed mainly in two subsequent phases. Firstly, a set-up which is able to generate and maintain a temperature gradient across a channel cross-section was designed, built, and then automated via software control. Secondly, this platform was tested with a glass-silicon-glass microfluidic chip, recording the fluid motion by tracking micrometric particles via General Defocusing Particle Tracking (GDPT) technique. This experiment was done for three conditions: only with thermal field, only with acoustic field and with the two combined.
The results validate the effectiveness of the platform in generating and maintaining the thermal field and have a good agreement with literature, although the acoustic field appeared undesirable due to some channel geometry flaws. The novelty of the project, i.e. the thermal-acoustic interaction, revealed itself to be quite complex. As predicted, high velocity fields were observed, associated with some unexpected flow behaviours, particularly along the length of the channel. Further measurements using a device with ideal channel geometry, together with a closer collaboration with the theoreticians who are able to explain the underlying physics, are needed to reveal the full picture of this novel phenomenon. (Less)
Popular Abstract
TIME: HOW TO STOP THIS SERIAL KILLER.
Late diagnosis implies countless early deaths. How can sound and heat help us tackling this problem? To find out we need to dive into the micro-scale world.
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author
Corato, Enrico LU
supervisor
organization
course
BMEM01 20202
year
type
H2 - Master's Degree (Two Years)
subject
keywords
Microfluidics, Ultrasound, Acoustofluidics, Thermal gradient, Thermoacoustic
language
English
additional info
2020-20
id
9033650
date added to LUP
2021-02-02 11:13:03
date last changed
2022-08-22 03:40:23
@misc{9033650,
  abstract     = {{This thesis aims at investigating the interaction between thermal gradients and acoustic fields in microfluidic devices. In the research branch of Acoustofluidics, which bridges together acoustics and fluid dynamics, inhomogeneity in the medium has gained great interest due to the novel physics behind and the potential in manipulating submicrometer particles. Concentration gradients of solute molecules have already been proven in previous studies to be effective means to obtain differences in fluid properties, such as density and compressibility, which induce acoustic body force and heavily affect the acoustic streaming. In this project another approach was taken, i.e. generating the inhomogeneity by thermal fields, to achieve a more stable and smooth variation in the thermophysical properties of the medium across the microchannel.
The thesis work developed mainly in two subsequent phases. Firstly, a set-up which is able to generate and maintain a temperature gradient across a channel cross-section was designed, built, and then automated via software control. Secondly, this platform was tested with a glass-silicon-glass microfluidic chip, recording the fluid motion by tracking micrometric particles via General Defocusing Particle Tracking (GDPT) technique. This experiment was done for three conditions: only with thermal field, only with acoustic field and with the two combined.
The results validate the effectiveness of the platform in generating and maintaining the thermal field and have a good agreement with literature, although the acoustic field appeared undesirable due to some channel geometry flaws. The novelty of the project, i.e. the thermal-acoustic interaction, revealed itself to be quite complex. As predicted, high velocity fields were observed, associated with some unexpected flow behaviours, particularly along the length of the channel. Further measurements using a device with ideal channel geometry, together with a closer collaboration with the theoreticians who are able to explain the underlying physics, are needed to reveal the full picture of this novel phenomenon.}},
  author       = {{Corato, Enrico}},
  language     = {{eng}},
  note         = {{Student Paper}},
  title        = {{Thermal Acoustic Flow inside an Ultrasound Resonator}},
  year         = {{2020}},
}