Dielectrophoresis Based Methods For Separating Particles On Lab-On-Chip PlatformsDickerson, Samuel J (2013) Dielectrophoresis Based Methods For Separating Particles On Lab-On-Chip Platforms. Doctoral Dissertation, University of Pittsburgh. (Unpublished) This is the latest version of this item.
AbstractLab-on-chip devices are an emerging microsystem technology in which laboratory functions are miniaturized into compact, chip-scale packages. Such devices enable analyses to be performed at lower cost and higher speed than with traditional methods. One major application area for these devices is their use in sorting and separating biological particles. In this dissertation, we present a new technique for separating biological particles on lab-on-chip platforms. The foundation of our method is dielectrophoresis, a technique where AC electric fields are used to manipulate particles in a fluid, based on their inherent electrical properties. These electrical properties reflect differences not just in size, but also capture subtle variations in the internal composition of the particle. Using a novel time-multiplexed combination of dielectrophoresis methods over very dense electrode arrays, we can create strong electric fields with a high degree of spatial resolution. When placed in the presence of these fields, particles with variations in composition can be made to experience different amounts of force, forces in opposite directions, or no force at all simply by applying fields of specific frequency and phase in particular regions of the electrode array. By time-multiplexing, or rapidly alternating the field configuration over time, we can exert differential forces on particles of varying types. Time-multiplexing dielectrophoresis enables separations between particle types to take place under conditions that would otherwise make them inseparable. The application of the method significantly loosens the requirements competing methods have on maintaining a buffer with specific electric properties and has the ability to increase the differential rate at which particles migrate apart. As a result of our method, the use of dielectrophoresis to separate particles becomes a viable alternative in real-world situations. To demonstrate our claims we have created a small library of five particle types, including yeast cells and polystyrene microspheres of varying types. We have selected appropriate electrical models for each of these particles and use the models to analytically validate our methodology. For this dissertation, we have also developed a novel lab-on-chip hardware platform to experimentally validate our models and demonstrate the effectiveness of our technique. The presented methodology and its implementation have the potential to serve as the basis for a new class of point-of-care, portable diagnostic devices by allowing researchers to sort and assay particles of interest based on their structure and composition without the use of expensive and destructive biochemical labeling techniques. Share
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