Chung, Sang Kug
(2011)
Micro-Object Manipulation Using Oscillating Bubbles.
Doctoral Dissertation, University of Pittsburgh.
(Unpublished)
Abstract
This thesis deals with the development of novel manipulation techniques of micro/mini objects using oscillating bubbles. Two major physical principles studied and applied are cavitational microstreaming flows and electrowetting on dielectric (EWOD) actuation in gaseous bubbles. Micro/mini bubbles oscillated and handled in 2-D and 3-D spaces using these two principles are key components serving as carriers of objects to be manipulated. The first type of manipulation system allows us to manipulate mini/micro objects on a 2-D space. A series of bubble operations (creation, elimination, and transportation) and object manipulations (capturing, carrying, and releasing) is extensively investigated in this configuration along with modeling and analysis. The capturing force is identified and completely confirmed as the acoustic radiation force through several experiments. Effects of the frequency and amplitude of acoustic excitation on capturing are quantified with high-speed imaging. The bubble elimination process is modeled by two sequential steps: catalytic reaction and dissolving process.In addition, the similar operations of capturing, carrying, releasing of objects are accomplished only using AC-EWOD, not using the acoustic excitation. In this case, the AC voltage (optimal frequency of 100 Hz) not only oscillates the bubble but also transports the oscillating bubble on the surface. However, the carrying efficiency is lower than the simultaneous actuations of acoustic excitation and EWOD. The second type of object manipulation system utilizes the capturing phenomenon by oscillating bubble. The main feature is that the oscillating bubble is deposited on a 3-D traversing rod tip, rather than a two-dimensional surface. So, it allows for object manipulation in a 3-D space. It is concluded from multiple experiments that the maximum carrying speed is highest near the bubble resonant frequency, meaning that the capturing force is proportional to the bubble oscillation amplitude.Finally, the cavitational streaming flow is extended to underwater propulsion. The key concept is to utilize the net momentum flux around the oscillating bubble. As a reaction force, the net momentum flux pushes or pulls the solid substrate on which the oscillating bubble sits. Using mini/micro glass rods, the propulsion mechanism is experimentally proved. The propulsion force is measured to be hundreds of nano-Newtons in a pendulum configuration.
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Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
|
| ETD Committee: |
| Title | Member | Email Address | Pitt Username | ORCID |
|---|
| Committee Chair | Cho, Sung Kwon | | | | | Committee Member | Kim, Kang | | | | | Committee Member | Schaefer, Laura | | | | | Committee Member | Chyu, Minking K | | | |
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| Date: |
3 August 2011 |
| Date Type: |
Completion |
| Defense Date: |
15 June 2009 |
| Approval Date: |
3 August 2011 |
| Submission Date: |
20 July 2009 |
| Access Restriction: |
5 year -- Restrict access to University of Pittsburgh for a period of 5 years. |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
Swanson School of Engineering > Mechanical Engineering |
| Degree: |
PhD - Doctor of Philosophy |
| Thesis Type: |
Doctoral Dissertation |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
Cell manipulation; electrowetting; microfluidics; oscillating bubble; underwater propulsion |
| Other ID: |
http://etd.library.pitt.edu/ETD/available/etd-07202009-140517/, etd-07202009-140517 |
| Date Deposited: |
10 Nov 2011 19:52 |
| Last Modified: |
15 Nov 2016 13:46 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/8466 |
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