Electromagnetic actuation for ferrofluid-based droplet microfluidics
Abstract/Contents
- Abstract
- Magnetic actuation is an attractive method for microfluidic manipulations, given that strong magnetic fields can be applied on biological materials or fluids with negligible physiological impact. Despite its common use in passive microfluidic systems, there's been limited development for active microfluidic systems, mainly due to the limitations of conventional magnetic sources. Permanent magnets, although magnetically strong, lack switching capability. Strong electromagnets are too large to be integrated in microfluidic systems and small electromagnets generate weak forces. This dissertation demonstrates the use of miniature electropermanent magnets (EPMs) for the first time in microfluidic systems. EPMs combine the switching capability of electromagnets with the strength of permanent magnets into a compact package. In this work, EPMs are integrated with PDMS microfluidic chips and used to manipulate aqueous droplets in an oil-based ferrofluid. A PDMS compatible ferrofluid is presented and used as the continuous phase for the droplet microfluidic system. Using fast EPM switching (under 100 microseconds), magnetic fields of up to 300 mT are generated in close proximity (under 200 micrometers) to the microchannels. On-demand droplet displacement is demonstrated and used for sorting. Displacement velocities up to 300 micrometers/s are demonstrated for 50 micrometer droplets. EPM-driven droplet size modulation is demonstrated and used to control the sizes of droplets during generation. Droplet size increases of up to 44% are demonstrated for a continuous stream and for a single droplet. In addition, cell viability is tested in the ferrofluid-based droplet microfluidic system. Cells are encapsulated in serum-free media droplets, surrounded by the ferrofluid continuous phase, and their viability is tracked over several hours. Results show that cell viability is not significantly affected by encapsulating them in droplets surrounded with ferrofluids with 4.5% concentration of passivated iron oxide nanoparticles. The work presented in this dissertation demonstrates that EPMs are a viable magnetic source for active microfluidic systems. Coupled with ferrofluids, EPM-driven microfluidics could present an attractive new direction for the field and enable new applications.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2016 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Padovani Blanco, José Iván |
|---|---|
| Associated with | Stanford University, Department of Electrical Engineering. |
| Primary advisor | Howe, Roger Thomas |
| Thesis advisor | Howe, Roger Thomas |
| Thesis advisor | Dutton, Robert W |
| Thesis advisor | Santiago, Juan G |
| Advisor | Dutton, Robert W |
| Advisor | Santiago, Juan G |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | José Iván Padovani Blanco. |
|---|---|
| Note | Submitted to the Department of Electrical Engineering. |
| Thesis | Thesis (Ph.D.)--Stanford University, 2016. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2016 by Jose Ivan Padovani Blanco
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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