Electrostatic Elastomer Devices for Reconfigurable High-Density Microfluidics.

Abstract

Components and systems for the scalable, very large-scale integration (VLSI) of thousands of microfluidic devices into Micro Total Analysis Systems (μTAS) are the fo-cus of much ongoing research. Most solutions to date have focused on either a) the scal-ing and modification of conventional pneumatically-driven elastomer microfluidics or b) the development of electrically or magnetically addressable fluidic components and sys-tems. Although these technologies have each solved the integration problem partially, they still leave something to be desired such as lack of on-chip power or degradation in chip performance due to cross contamination. This thesis presents the design, fabrication, and characterization of an electrostati-cally actuated user-reconfigurable elastomer microfluidic system intended for VLSI mi-crofluidics. Capacitor plates form top (deformable) and bottom of the micro chan-nel/chamber, facilitating gap-closing actuation. Device fabrication followed standard mi-cromaching process. We also present experimental results of flow and pressure data for valves, pumps and demonstrate various multi-component configurations of the system. The presented technology is compatible with standard polydimethylsiloxane (PDMS) mi-crofluidics, has actuation voltages low enough to be driven by commercial CMOS IC’s and can be used to displace aqueous, gaseous and lipid phases. By adding thin film metal flexures into the PDMS polymer, individual elastomer channels were made to self-close without the use of pneumatics via the application of 10 – 20 V, 5 MHz signals synthesized digitally by a microcontroller and a radio-frequency amplifier IC. These valves were integrated into discrete micro valve and three-valve peristaltic micro pumps. A single valve was able to hold 6 psi pressure, and the peristaltic pump had a flow rate 4.4 valve-volume/min (1 - 2 nL/min), depending on the actuation frequency and device configuration. Further, these valves were arranged into hexagonal or quadricular arrays with 75% fill factor. During use, valves were selected to be permanently closed, permanently open or addressable; this allowed for the on-the-fly determination of channels, valves and pumps. We demonstrated various multi-component configurations of the system: distributed valving, fluid switching, flow splitting and mix-ing. The primary contribution of this technology is to provide a scalable reconfigurable liquid manipulation platform for the very large scale integration of μTAS.Ph.D.Mechanical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/61769/1/mpchang_1.pd