To harness the wealth of success and computational power from the microelectronics industry, lab-on-a-chip (LOAC) applications should be fully integrated with silicon platforms. This works demonstrates a dielectrophoresis-based LOAC device built entirely on silicon using standard CMOS (complementary metal oxide semiconductor) processing techniques. The signal phases on multiple electrodes were controlled with only four electrical contacts, which connected to the device using three metal layers separated with interlayer dielectric. Indium tin oxide was deposited on a milled plastic lid to provide the conductivity and optical clarity necessary to electrically actuate the particles and observe them. The particles and medium were in the microfluidic chamber formed by using conductive glue to bond the plastic milled lid to the patterned silicon substrate. A correlation between the particle velocities and the electric field gradients was made using video microscopy and COMSOL Multiphysics ® simulations.

To harness the wealth of success and computational power from the microelectronics industry, lab-on-a-chip (LOAC) applications should be fully integrated with silicon platforms. This works demonstrates a dielectrophoresis-based LOAC device built entirely on silicon using standard CMOS (complementary metal oxide semiconductor) processing techniques. The signal phases on multiple electrodes were controlled with only four electrical contacts, which connected to the device using three metal layers separated with interlayer dielectric. Indium tin oxide was deposited on a milled plastic lid to provide the conductivity and optical clarity necessary to electrically actuate the particles and observe them. The particles and medium were in the microfluidic chamber formed by using conductive glue to bond the plastic milled lid to the patterned silicon substrate. A correlation between the particle velocities and the electric field gradients was made using video microscopy and COMSOL Multiphysics ® simulations.

Thesis (M.S.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 79-86). Also available on the World Wide Web.

Thesis (Ph.D.)--Kent State University, 2006. / Title from PDF t.p. (viewed Sept. 19, 2006). Advisor: John L. West. Keywords: nematic isotropic interface, liquid crystal colloids, dielectrophoresis, microparticle, drag effect, Raman mapping, IR imaging. Includes bibliographical references (p. 152-164).

Thesis (Ph. D.)--Oregon State University, 2008. / Printout. Includes bibliographical references (leaves 133-137). Also available on the World Wide Web.

Lau, Fong Ting. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 73-77). / Abstracts in English and Chinese. / ABSTRACT --- p.III / 摘要 --- p.IV / PUBLICATIONS CORRESPOND TO THIS THESIS --- p.V / ACKNOWLEDGEMENT --- p.VI / TABLE OF CONTENTS --- p.VIII / LIST OF FIGURES --- p.X / LIST OF TABLES --- p.XII / Chapter CHAPTER I. --- INTRODUCTION --- p.1 / Chapter 1.1 --- Background --- p.1 / Chapter 1.1.1 --- Unique Properties of Gold Nanoparticles Possess --- p.1 / Chapter 1.1.2 --- Synthesis of Gold Nanoparticles --- p.3 / Chapter 1.1.3 --- Aggregation or Agglomeration of Gold Nanoparticles --- p.4 / Chapter 1.1.4 --- Fabrication of Well-ordered Structures Using Gold Nanoparticles --- p.6 / Chapter 1.2 --- Objective --- p.7 / Chapter 1.3 --- Organization --- p.9 / Chapter CHAPTER II. --- ARCHITRCTURE OF AUTOMATED MICRO-ROBOTIC SPOTTING SYSTEM --- p.10 / Chapter 2.1 --- Micro-sized Capillary Probes --- p.12 / Chapter 2.1.1 --- Importance of Fabrication of Micron-sized Capillary Probe Tip --- p.12 / Chapter 2.1.2 --- Experimental Procedure of Fabrication of Capillary Probe --- p.14 / Chapter 2.1.3 --- Experimental Result of Fabrication of Capillary Probe --- p.15 / Chapter 2.2 --- Programmable X-Y-Z Manipulator --- p.16 / Chapter 2.3 --- Programmable Hydraulic Syringe Pump --- p.16 / Chapter 2.4 --- CCD Video Microscope System --- p.17 / Chapter 2.5 --- Chapter Conclusion --- p.17 / Chapter CHAPTER III. --- MANIPULATION OF UNMODIFIED GOLD NANOPARTICLES BY DIELECTROPHORESIS --- p.18 / Chapter 3.1 --- Methodology of Manipulation of Gold Nanoparticles --- p.18 / Chapter 3.1.1 --- Self-assembly of Crystals by Capillary Force Induced by Solvent Evaporation --- p.19 / Chapter 3.1.2 --- Position Control by Dielectrophoretic (DEP) Force --- p.21 / Chapter 3.2 --- Experimental Preparation and Setup --- p.22 / Chapter 3.2.1 --- Microelectrodes Fabrication --- p.22 / Chapter 3.2.2 --- Circuit --- p.23 / Chapter 3.2.3 --- Injection of Solution by Microspotting Technique --- p.24 / Chapter 3.3 --- Experimental Procedure --- p.24 / Chapter 3.4 --- Experimental Result --- p.24 / Chapter 3.4.1 --- Process of Crystal Formation by Combining the Capillary Force and DEP --- p.24 / Chapter 3.4.2 --- Position of Crystal Formed between Microelectrodes --- p.25 / Chapter 3.4.3 --- Yield of Crystal Formed between Microelectrodes by Varying Voltage Applied --- p.27 / Chapter 3.5 --- Surface Analyses --- p.29 / Chapter 3.5.1 --- Scanning Electron Microscopy and Energy-Disperse X-ray Spectroscopy Analysis --- p.30 / Chapter 3.5.2 --- Atomic Force Microscope Analysis --- p.31 / Chapter 3.6 --- Possibilities served as Humidity Sensors --- p.33 / Chapter 3.7 --- Chapter Conclusion --- p.35 / Chapter CHAPTER IV. --- THEORETICAL ANALYSES OF GOLD NANOPARTICLES MANIPULATION --- p.37 / Chapter 4.1 --- Structure of Gold nanoparticles - Presence of Stabilizing Ions --- p.37 / Chapter 4.2 --- Theoretical Force Analysis Acting on Gold Nanoparticles --- p.39 / Chapter 4.2.1 --- Governing Equations --- p.39 / Chapter 4.2.2 --- Experimental Analysis --- p.45 / Chapter 4.3 --- Concentration of Gold Nanoparticles in Gold Colloidal Solution --- p.47 / Chapter 4.4 --- Chapter Conclusion --- p.48 / Chapter CHAPTER V. --- MODIFICATION OF GOLD NANOPARTICLES SURFACE --- p.50 / Chapter 5.1 --- Working Principle of Surface Modification of Gold Nanoparticles --- p.50 / Chapter 5.2 --- Criteria of Choosing the Adsorbed Molecules for Chemisorption --- p.52 / Chapter 5.3 --- Experimental Procedures of Surface Modifications --- p.54 / Chapter 5.4 --- Experimental Result of Surface Modification of Gold Nanoparticles --- p.58 / Chapter 5.4.1 --- Effect of Concentration of Dodecanethiol --- p.58 / Chapter 5.4.2 --- Stability of Surface Modified Gold Nanoparticles --- p.59 / Chapter 5.5 --- Chapter Conclusion --- p.61 / Chapter CHAPTER VI. --- MANIPULATION OF MODIFIED GOLD NANOPARTICLES BY DIELECTROPHORESIS --- p.62 / Chapter 6.1 --- Experimental Setup --- p.62 / Chapter 6.2 --- Experimental Result --- p.63 / Chapter 6.2.1 --- Comparison between Modified and Unmodified Gold Nanoparticles --- p.63 / Chapter 6.2.2 --- Manipulation Experiments using Different Frequency --- p.64 / Chapter 6.3 --- PDMS Microfluidic Channel System --- p.68 / Chapter 6.3.1 --- System Design --- p.68 / Chapter 6.3.2 --- Fabrication --- p.68 / Chapter 6.4 --- Chapter Conclusion --- p.69 / Chapter CHAPTER VII. --- CONCLUSION --- p.71 / BIBLIOGRAPHY --- p.73

Dielectrophoresis and electrorotation are receiving increasing attention as useful phenomena for the characterisation and physical manipulation of cells. The primarily concern of this investigation was to determine whether these techniques can interpret accurately the dielectric properties of biological cells with an appropriate dielectric shell model. In this study, synthetic vesicles have been used as the testing samples in electrorotation experiments to verify the reliability of these techniques. By using the electrorotation technique with the dielectric shell models, dielectric properties of vesicles could be analysed very accurately and the results were in agreements with the observed morphology and membrane properties. The physical structure of the vesicles varied from a simple one such as unilamellar vesicle, to a more complex structure such as the oligolamellar and multilamellar form. The morphology and membrane structure of the vesicles were also characterised by fluorescence microscopy, flow cytometry and electron spin resonance using spin probes. This allowed this validification of the application of the dielectric shell theory for analysis of simple cellular systems. The second objective of this work was to extend the potential used of the electrorotation technique, and not only for the analysis of cellular systems. Electrorotation was also performed on single stranded DNA oligonucleotides, covalently bound onto the surface of microscopic-sized latex beads. Different types of the DNA oligonucleotides exhibited different electrorotation responses according to their different base sequences. This has shown that the electrorotation technique can be used as an analytic tool to identify different sequences of DNA oligonucleotide.

No description available.

Immunotherapy is becoming recognized as a superior treatment for cancer. In recent years, chimeric antigen receptor (CAR) therapy is among the immunotherapies that has had growing success rates. CAR T-cell therapy takes patient’s T-cells and encodes them with a CAR expressing gene, which can then target their cancer cells. However, there are some dangers associated with this therapy. If a cancer cell is mistakenly transfected with the CAR molecule, it can become resistant to the therapy. Using the electric properties of the cells, we have created a technique that can purify the T-cells from the remaining cancer cells using microfluidics and dielectrophoresis (DEP). Then, to further improve the therapy, the sample is electroporated following being patterned using DEP forces, which transfects the cells without using viral vectors and provides longer CD19 expression.

The research presented in this dissertation is the result of our laboratory's effort to develop a microfluidic platform to interrogate, manipulate, isolate, and enrich rare mammalian cells dispersed within heterogeneous populations. Relevant examples of these target cells are stem cells within a differentiated population, circulating tumor cells (CTCs) in the blood stream, and tumor initiating cells (TICs) in a population of benign cancer cells. The ability to isolate any of these rare cells types with high efficiency will directly lead to advances in tissue engineering, cancer detection, and individualized medicine. This work lead directly to the development of a new cell manipulation technique, termed contactless dielectrophoresis (cDEP). In this technique, cells are isolated from direct contact with metal electrodes by employing fluid electrode channels filled with a highly conductive media. Thin insulating barriers, approximately 20 μ­m, serve to isolate the fluid electrode channels from the low conductivity sample buffer. The insulating barriers in a fluid-electrical system create a number of unique and interesting challenges from an electrical engineering standpoint. Primarily, they block the flow of DC currents and create a non-constant frequency response which can confound experimental results attempting to characterize the electrical characteristics of cells. Due to these, and other, considerations, the use of high-voltage high-frequency signals are necessary to successfully manipulate cells. The effect of these high frequency fields on cells are studied and applied to microfluidic and tissue level applications. In later chapters, theoretical and experimental results show how high frequency and pulsed electric fields can ablate cells and tissue. Understanding the parameters necessary to electroporate cells aids in the development of cDEP devices where this phenomenon is undesirable and gives insight towards the development of new cancer ablation therapies where targeted cell death is sought after. This work shows that there exists a finite frequency spectrum over which cDEP devices can operate in which cells are minimally affected by the induced electric fields. Finally, lessons learned in the course of the development of cDEP were adapted and applied towards cancer ablation therapies where electroporation are favorable. It was found that bursts of high frequency pulsed electric fields can successfully kill cells and ablate tissue volumes through a process termed High Frequency Irreversible Electroporation (H-FIRE). This technique is advantageous as these waveforms mitigate or eliminate muscle contractions associated with traditional IRE technologies. Similarly, the use of fluid electrodes in cDEP inspired the use of an organs vascular system as the conductive pathway to deliver pulses. This novel approach allows for the ablation of large volumes of tissue without the use of puncturing electrodes. These techniques are currently undergoing evaluation in tissue engineering applications and pre-clinical evaluation in veterinary patients. / Ph. D.