Electrokinetic and acoustic manipulations of colloidal and biological particles

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Title: Electrokinetic and acoustic manipulations of colloidal and biological particles
Author: Park, Seungkyung
Abstract: Recent advances in microfluidic technologies have enabled integration of the functional units for biological and chemical analysis onto miniaturized chips , called Labon - a -Chip (LOC ) . However , the effective manipulation and control of colloidal particles suspended in fluids are still challenging tasks due to the lack of clear characterization of particle control mechanisms . The aim of this dissertation is to develop microfluidic techniques and devices for manipulating colloids and biological particles with the utilization of alternating current (AC ) electric fields and acoustic waves . The dissertation presents a simple theoretical tool for predicting the motion of colloidal particles in the presence of AC electric field . Dominant electrokinetic forces are explained as a function of the electric field conditions and material properties , and parametric experimental validations of the model are conducted with particles and biological species . Using the theoretical tool as an effective framework for designing electrokinetic systems , a dielectrophoresis (DEP ) based microfluidic device for trapping bacterial spores from high conductivity media is developed . With a simple planar electrode having well defined electric field minima that can act as the targetattachment / detection sites for integration of biosensors , negative DEP trapping of spores on patterned surfaces is successfully demonstrated . A further investigation of DEP colloidal manipulation under the effects of electrothermal flow induced by Joule heating of the applied electric field is conducted . A periodic structure of the electrothermal flow that enhances DEP trapping is numerically simulated and experimentally validated . An acoustic method is investigated for continuous sample concentration in a microscale device . Fast formation of particle streams focused at the pressure nodes is demonstrated by using the long -range forces of the ultrasonic standing waves (USW ) . High frequency actuation suitable for miniaturization of devices is successfully applied and the device performance and key parameters are explained . Further extension and integration of the technologies presented in this dissertation will enable a chip scale platform for various chemical and biological applications such as drug delivery , chemical analyses , point -of -care clinical diagnosis , biowarfare and biochemical agent detection /screening , and water quality control .
URI: http : / /hdl .handle .net /1969 .1 /ETD -TAMU -3199
Date: 2009-05-15

Citation

Electrokinetic and acoustic manipulations of colloidal and biological particles. Available electronically from http : / /hdl .handle .net /1969 .1 /ETD -TAMU -3199 .

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