UCLA

The ability to manipulate biological cells and micrometer-scale particles plays an important role in many biological and colloidal science applications. However, conventional manipulation techniques, such as optical forces, electrokinetic forces (electrophoresis, dielectrophoresis (DEP), and traveling-wave dielectrophoresis), magnetic forces, acoustic forces (surface standing acoustic waves (SAW), and bulk standing acoustic waves(BAW)), and hydrodynamic flows, cannot achieve high resolution and high throughput at the same time. While electrokinetic forces and other mechanisms provide higher throughput than optical mechanism, but lack the flexibility or the spatial resolution necessary for controlling individual particles. None of which could provide high resolution, throughput and versatility in clinical applications.

In this dissertation, I present a novel DEP concept for high resolution, throughput and versatility microns-sized particle and biological cell manipulation in high-speed flows. Using novel three-dimensional (3D) polydimethylsiloxane (PDMS) thin-film fabrication platform I developed, true heterogeneous integration of electronics on hard substrates (silicon and/or glass) and PDMS are demonstrated for the first time to create 3D electric field across the entire large area (couple centimeter across) 3D microfluidic channel networks. Which enables broad applications, such as sheathless sub-micron particle focusing in high-speed flows, tunable micron-sized particle and cell focusing in high-speed flows, and ultra-high precision particle size-based sorting. Within all sections, experiments were performed with beads to verify the concept of each platform and then with cells to demonstrate qualitative and quantitative operation of the performance. These technologies is now well poised to enable the development of biological assays that are currently unavailable.