Field driven microfluidic actuators for micro total analysis systems: Magnetohydrodynamic micropump and microfluidic switch, electrostatic DNA extractor, dielectrophoretic DNA sorter

This dissertation describes novel field driven microfluidic actuators that can be integrated into micro total analysis systems (μTAS). Each of the devices fabricated and tested uses electric and/or magnetic fields to produce action. Magnetohydrodynamic (MHD) pumping, which uses the Lorentz force to propel electrolytic solutions in a microchannel, is demonstrated using AC electrical currents across the channel and a synchronous AC magnetic field from an electromagnet. An AC MHD microfluidic switch is demonstrated by fabricating a pair of micropumps on a single chip using only one electromagnet. MHD pumping enables routing of biological samples in complex microchannel designs. Electrostatic force is used in the DNA extractor, where two flow streams flow next to one another along a microchannel without mixing. Using the inherent negative charge on the DNA, extraction from one flow stream to another is accomplished using a DC electric field to attract the DNA to the positive electrode. Dielectrophoretic force combined with hydrodynamic force is used in the DNA sorter. In the presence of a non-uniform AC electric field, DNA is polarizable and is attracted to areas of high electric field intensity. The non-uniformity of the electric field can be varied to trap different DNA sizes in a flow stream. These field-driven microfluidic actuators can enable integrated μTAS solutions for the detection of harmful biological agents.