High-Frequency Electronics for Contactless Dielectrophoresis
Caldwell, John Lawrence
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The field of sample enrichment is currently receiving a large amount of attention because it is essential to reduce the time required for many laboratory processes. Dielectrophoresis, or the motion of a polarized particle in the presence of a non-uniform electric field, has emerged as a promising method for biological sample concentration. By relying upon electrical properties that are intrinsic to a cell or microparticle, dielectrophoretic concentration avoids the need for sample preparation procedures which can greatly reduce the throughput of a system. Contactless Dielectrophoresis (cDEP) is a promising manifestation of dielectrophoresis in which the electrode structures that provide the non-uniform electric field are physically separated from the sample by a thin dielectric barrier. This work presents two methods for providing the high-voltage and high-frequency signal necessary to generate a non-uniform electric field in the sample channel of a cDEP device. The first method, an oscillator-based system, was able to produce DEP trapping and pearl-chaining of THP-1 and MCF-7 breast cancer cells in a cDEP device. The second method presented here utilizes an amplifier and transformer combination to generate very high voltages over a wide range of frequencies. Finally, electrorotation, or the spin imparted to a particle due to a rotating electric field has proven to be an extremely useful analysis of a cell's dielectric properties. A wideband, computer controlled function generator, outputting four sinusoidal waveforms in quadrature is presented. This device was able to produce outputs with the proper alignment over the range of 10 Hz to 100MHz.
- Masters Theses