2 options
Light-driven Levitation of Ultralight Macroscopic Plates / John Cortes.
- Format:
- Book
- Thesis/Dissertation
- Author/Creator:
- Cortes, John, author.
- Language:
- English
- Subjects (All):
- Mechanical engineering.
- Nanotechnology.
- Mechanical engineering and applied mechanics--Penn dissertations.
- Penn dissertations--Mechanical engineering and applied mechanics.
- Local Subjects:
- Mechanical engineering.
- Nanotechnology.
- Mechanical engineering and applied mechanics--Penn dissertations.
- Penn dissertations--Mechanical engineering and applied mechanics.
- Genre:
- Academic theses.
- Physical Description:
- 1 online resource (155 pages)
- Contained In:
- Dissertations Abstracts International 81-06B.
- Place of Publication:
- [Philadelphia, Pennsylvania] : University of Pennsylvania ; Ann Arbor : ProQuest Dissertations & Theses, 2019.
- Language Note:
- English
- System Details:
- Mode of access: World Wide Web.
- text file
- Summary:
- The term "Micro-flyers" has generally been associated with centimeter-scale devices such as robotic insects or miniaturized drones. Due to manufacturing and aerodynamics challenges, propulsion at even smaller, sub-centimeter scales has historically been very difficult. In this thesis, we present the novel idea that light-driven photophoretic force can be used as a means of propulsion, which can then be used to levitate ultralight plates under several ambient and reduced pressure conditions. The photophoretic force is generated by a difference in temperature in a solid body or within the walls of a channel. We have used this unique phenomenon to develop micro-hovercrafts, which range from a few millimeters up to a centimeter in size and can hover hundreds of microns above an engineered low-stiction substrate at atmospheric pressure conditions. Under these conditions, gas flows from the cold end to the hot end, where a carbon nanotube layer absorbs incident light and heats up, resulting in the thermal transpiration flow. This flow then creates an overpressure underneath the plate, which causes it to lift-off and maintain a hovering gap between 300 µm and 600 µm for extended periods of time.The ultralight plates consist of a microfabricated plate metamaterial called nanocardboard, which is made from two face sheets interconnected by channels and features wall thicknesses in the 35-100 nm range, giving them areal densities as low as 0.5 g/m2. We also show the plate's capabilities to fly at heights above 10 mm above a fine metal mesh at reduced pressures (as low as 10 Pa inside of a small vacuum chamber), which shows the potential of mid-air levitation without the dependence on a solid substrate. Not only can the plates fly at reduced pressures, but they also display the ability to liftoff and move a payload. We have developed theoretical models which are able to predict both the low-height hovering behavior as well as the reduced pressure capabilities of our ultralight plates. We show that our plates are excellent candidates for a novel approach to conducting atmospheric research in the Earth's mesosphere as well as the Martian surface (given their ranges of ambient pressure).
- Notes:
- Source: Dissertations Abstracts International, Volume: 81-06, Section: B.
- Advisors: Bargatin, Igor; Committee members: Kevin Turner; Howard Hu.
- Department: Mechanical Engineering and Applied Mechanics.
- Ph.D. University of Pennsylvania 2019.
- Local Notes:
- School code: 0175
- ISBN:
- 9781088343135
- Access Restriction:
- Restricted for use by site license.
- This item is not available from ProQuest Dissertations & Theses.
- This item must not be sold to any third party vendors.
The Penn Libraries is committed to describing library materials using current, accurate, and responsible language. If you discover outdated or inaccurate language, please fill out this feedback form to report it and suggest alternative language.