Course C-1 (9:00 am -12:00am, June 5, 2011)
Microfluidics: Device Science and Technology
Microfluidics is a multidisciplinary field, intersecting engineering and science, dedicated to systems designed and fabricated for dealing with the behavior, control and manipulation of tiny amounts of fluids; the systems involve liquids and/or gases either in a primary or in a secondary role. The behavior of fluids at the microscale can differ from that at the macroscale; as the characteristic length scale of a system decreases, surfaces forces naturally become more dominant than body forces with a cross-over scale of about 1 mm. Thus, at small scales ranging between several hundred nanometers to several hundred micrometers, interesting and sometimes unintuitive properties appear.
This short course on device science and technology related to microfluidics features two parts; the first is dedicated to fabrication technologies of and diagnosis of fluid flow in microfluidic systems, while the second deals with fundamentals of microscale gas and liquid flows. Micromachining techniques used in fabricating microfluidic devices will be reviewed; this will include silicon-, glass-, polymer-, and protein-based technologies, with an emphasis on selectively functionalized surface properties. The discussion on micro flow diagnosis will include a review of sensing principles and measurements techniques; measurements of fluid flow properties in microchannels, such as velocity and pressure, will be described.
The second part will analyze the microscale physics of fluids; both the governing equations and boundary conditions for gas and liquid flows will be revisited. Control parameters such as Knudsen number for gaseous slip flow, Debye number for electrokinetically-driven liquid flow, and Eringen number for polar mechanic effects will be introduced. The velocity slip boundary condition for gas flow at the slip flow regime will formally be derived allowing linear and non-linear close-form analytical solutions of gas flow through uniform and non-uniform microchannels. The electrical double layer concept will be discussed and utilized for calculating simple and complex electroosmotic flows. Finally, polar mechanics effects will be reviewed, and the flow of micropolar fluids in microchannels will be analyzed.
Prof. Yitshak Zohar: Dr. Zohar’s research focuses on the development of micro/nanotechnology and fabrication of microfluidic devices for bio/chemical/medical applications. His lab has developed novel surface-chemistry techniques that enable selective manipulation of surface properties of fluidic microchannels and nanoparticles. These techniques have found a wide range of applications in life sciences, and are being used in several projects on campus. Microchannels functionalized with bio-active layers have been developed for specific capture of circulating metastatic tumor cells (CTCs) from blood samples of cancer patients in vitro. The lab is further developing ‘smart’ nanoparticels, with encapsulated anti-cancer drug in their core and targeting ligands on their surface, designed to specifically destroy CTCs in vivo in effort to eradicate the cancer disease. Other projects include the controlled dissociation of fresh brain tissue into viable neurons suitable for subsequent cell culture utilizing microfluidic systems; the investigation of pollen-tube/ovule interaction, particularly the attraction and repulsion signaling processes, using a microchannel-based assay; and protein-fiber formation in microfluidic devices.
Dr. Zohar’s work is highly interdisciplinary and he collaborates with many investigators in the Colleges of Engineering, Science and Medicine.