Microfabricated continuous flow separation and manipulation systems for human whole blood

The objective of the research in this dissertation is to develop microsystem based separation technologies for whole cell cancer analysis using human whole blood as the input sample. This research work is carried out with two different approaches; one based on a miniaturized cascade magnetophoresis system and a second based on dielectrophoresis. The miniaturized systems can be fabricated using MEMS technologies combined with plastic fabrication techniques.;The design, fabrication, packaging, and characterization of several versions of the magnetophoresis and dielectrophoresis microsystems for whole cell cancer analysis in human whole blood sample are presented. Each microsystem consists of five elements that are essential for the successful separation and/or manipulation of cells. Those essential components include microfluidic channels, inlet/outlet ports, ferromagnetic structures and/or comb-shaped electrodes, a microfluidic interface, and system packaging. For the operation of each microsystem, a blood or tumor cell sample is introduced into a device through a tubing and an SLA-based interface. In the magnetophoresis system, the RBCs or the magnetic cells in the sample experience a strong magnetophoretic force under a non-uniform magnetic field created by external permanent magnets and electroplated ferromagnetic structures. This allows the RBCs to be separated from the nucleated blood cells or the tagged cells to be separated from the non-magnetic cells. In the dielectrophoresis system, cells with different dielectric properties experience either positive or negative dielectrophoretic force under a non-uniform electric field created by an external AC signal and comb-shaped electrodes and move from their original positions in a laminar flow pattern to different positions.;The first magnetophoresis microsystem, the six-stage cascade paramagnetic mode magnetophoretic separation system, was designed and has successfully shown high throughput RBC separation from a human whole blood sample. The second magnetophoresis microsystem was developed for the isolation of malignant cancer cells from benign tumor cells and has successfully separated malignant tumor cells tagged with magnetic nanoparticles based on their surface expression level of a specific protein from benign tumor cells. Additionally, in an effort to improve the throughput of RBC removal from a non diluted whole blood sample, a magnetophoresis system with 40 separation stages is proposed and designed. Two dielectrophoresis systems were developed; one dielectrophoresis system tested its switching and separation capability based on the native dielectric properties of different cell types, while the other investigated the frequency response of different cell types by measuring their crossover frequencies in a medium with different conductivity. Additionally, an integrated cascade system contains magnetophoresis and dielectrophoresis components is proposed and designed.