COMPACT NANOSECOND PULSED POWER TECHNOLOGY WITH APPLICATIONS TO BIOMEDICAL ENGINEERING, BIOLOGY, AND MEDICINE by Xianyue Gu A Dissertation Presented to the FACULTY OF THE GRADUATE SCHOOL UNIVERSITY OF SOUTHERN CALIFORNIA In Partial Fulfillment of the Requirements for the Degree DOCTOR OF PHILOSOPHY (MATERIAL SCIENCE) August 2006 Copyright 2006 Xianyue Gu UMI Number: 3237721 3237721 2007 Copyright 2006 by Gu, Xianyue UMI Microform Copyright All rights reserved. This microform edition is protected against unauthorized copying under Title 17, United States Code. ProQuest Information and Learning Company 300 North Zeeb Road P.O. Box 1346 Ann Arbor, MI 48106-1346 All rights reserved. by ProQuest Information and Learning Company. ii Dedication To my parents, my husband, and my unborn children. iii Acknowledgements With sincere gratitude, I thank Dr. Martin Gundersen for his vision, guidance, support and encouragement; Dr. Edward Goo and Dr. Chongwu Zhou for serving on my dissertation committee; Dr. Terence G. Langdon, Dr. Florian B. Mansfeld, and Dr. Steven R. Nutt for serving on my Ph.D. qualifying exam committee; Dr. Andrus Kuthi for sharing his knowledge in pulsed power. I would like to thank my colleagues, Dr. P. Thomas Vernier, Dr. Chunqi Jiang, Qiong Shui, Yinghua Sun, Tao Tang, Fei Wang, Matthew Behrend, and many other friends for their kindness and help throughout my graduate study at University of Southern California. I also thank Song Han, Bo Lei, Wu Jing for their help in the pulsed laser deposition. Thanks are also owed to Noreen Tamanaha for her countless work. iv Table of Contents Dedication ii Acknowledgements iii List of Tables vi List of Figures vii Abstract xi 1 Introduction 1.1 Pulsed Power Technology for Biomedical Applications 1.2 Research Issues in Compact Nanosecond Pulsed Power System 1.2.1 At component level 1.2.2 At system level 1.2.3 At application level 1.3 Thesis Organization 1 2 Comparison of Si, GaAs, SiC and GaN FET-type Semiconductor Switches 2.1 Introduction 2.2 Simulation Setup 2.2.1 Physical models for simulations 2.2.2 Heat flow equation 2.2.3 Device structure 2.2.4 Defect parameters 2.3 Results and Discussion 2.3.1 Effects of defects 2.3.2 Comparison of materials 2.4 Summary 17 v 3 High Energy Density Capacitor 3.1 Introduction 3.2 Experiments 3.2.1 PLD setup 3.2.2 Experimental procedure 3.3 Results and Discussion 3.3.1 Crystalline structure 3.3.2 Dielectric properties 3.4 Summary 51 4 Compact Pulse Generator for Nano-electroperturbation of Biological Cells 4.1 Introduction 4.2 Blumlein Pulse Forming Network 4.2.1 Electric load 4.2.2 Modeling of water Blumlein 4.2.3 Fabrication of water Blumlein 4.3 Four-channel Resonant Charging Circuit 4.4 Operation and Conclusion 60 5 Impulse Catheter Devices for Medical Applications 5.1 Impulse Catheter Device Design 5.1.1 Design requirements 5.1.2 Device design 5.2 Materials and Methods 5.3 Evaluation of Impulse Catheters 5.3.1 Load impedance 5.3.2 Electric field distribution 5.3.3 Effect volume 5.4 in vivo Response to Nanopulses Delivered via Impulse Catheter 5.5 Dielectric Dispersion of Biological Load 5.6 Conclusions 77 6 Summary and Future Work 102 Reference List 107 vi List of Tables 1.1 Summary of Various Switch Parameters in Pulsed power Application 6 2.1 Summarized parameters for mobility models. 32 2.2 Summarized parameters for the impact ionization model. 35 2.3 Heat capacitance and thermal conductivity for various materials. 38 2.4 Trap parameters. 40 3.1 Comparison of various methods for BST dielectric layer growth. 53 5.1 Measured maximum operation voltages of RF catheters and microwave cable. Measurement was carried out by high voltage pulses with pulse width of 150ns. 81 5.2 Summary of needle-type catheters. 82 vii List of Figures 1.1 Simple inductive storage discharge circuit and voltage and current waveforms with RL decay. 12 1.2 SOS switching circuit schematic and voltage and current waveforms. 12 1.3 Simple capacitive storage discharge circuit and output voltage with RC decay. 14 2.1 Theoretical merits of different semiconductor materials. 19 2.2 Fitted GaAs mobility models. 22 2.3 Fitted 4H-SiC mobility models. 25 2.4 Fitted Wurtzite GaN mobility models. 29 2.5 Electric field dependency of electron and hole impact ionization rate at T=300 K for GaAs. 34 2.6 Electric field dependency of electron and hole impact ionization rate at T=300 and 400 K for 4H-SiC. 34 2.7 Electric field dependency of electron and hole impact ionization rate at T=300 for Wurtzite GaN. 35 2.8 Schematic of a half-cell of the VJFET. 39 2.9 Cross sectional structure of the Si vertical MOSFET. 39 2.10 Predicted hold off voltages for Si vertical MOSFET, GaAs, 4H-SiC, and GaN vertical JFETs. 41 viii 2.11 Predicted electron density in the GaAs vertical JFET at Vds = 300 V with and without the EL2 defect. The x-axis is the distance from the source toward the drain. 42 2.12 Predicted electron mobility in the GaN vertical JFET. The x-axis is the distance from the source toward the drain. 43 2.13 Predicted I - V curves for the GaN vertical JFET. The dark curves are results for perfect GaN. The gray curves are for GaN with defects. 44 2.14 Predicted I-V curve for the 4H-SiC vertical JFET. The gray curves are results for the perfect material. The dark curves include the effects of defects. 45 2.15 Predicted hold-off voltage for the 4H-SiC JFET. 45 2.16 Hole concentration results from 4H-SiC JFET simulation without defects and with defects. 46 2.17 Comparison of predicted hold-off voltages for the Si, GaAs, SiC, and GaN devices. The plot for the GaN JFET was obtained at Vgs= -25V. 48 2.18 Comparison of predicted switching performances of the Si, SiC, GaN and GaAs devices. 48 2.19 Predicted effect of gate bias on the hold-off voltage of the GaN JFET. 49 2.20 Ratio between temperature rising and current density for GaAs, GaN and SiC JFET’s. 49 3.1 Schematic of PLD setup. 55 3.2 XRD patterns for BST films deposited and annealed at (a) 500˚C, (b) 600˚C and (c) 700˚C. 57 3.3 Average grain sizes vs. deposition temperature. 58 3.4 Dielectric constant and dissipation factor of the film vs. frequency. 59 4.1 2-Transmission line Blumlein. 62 4.2 3.8 inch (5 ns) Blumlein model and simulated output wave form. 64 ix 4.3 750 mil Blumlein model and simulated output wave form illustrating the impact of edge effects at shorter pulse widths. 65 4.4 The initial semi-circular outward propagating input wave. 66 4.5 The input waveform boundary as the wave propagates through the primary transmission line. 66 4.6 Pulse shape improvement using internal reflections. 67 4.7 Picture of fabricated 5-ns and 2-ns Blumlein for 10 ohm cuvette load. 68 4.8 2 ns Contoured water Blumlein design schematic. 69 4.9 5 ns water Blumlein design schematic. 70 4.10 Schematic of flyback mode. 71 4.11 4-resonant-channel charging circuit and single resonant channel circuit. 72 4.12 Balancing drain currents in four resonant channels by modifying ground loop layout on printed circuit board. 73 4.13 Charging waveform, 8.5kV peak, 355ns rise time. Total peak current on primary of the transformer is 400 A. 74 4.14 Circuit diagram of the lumped element transmission line. 75 4.15 Picture of the compact pulsed generator based on a lumped transmission line and a four-channel resonant charging circuit. 75 4.16 Output voltage, 5.5 kV peak and 5.4 ns rise time, and 9.2 ns pulse width. 76 5.1 Line impedance as a function of frequency for a commercial RF ablation catheter transmission line, and input and output pulses showing distortion of typical line. 78 5.2 The flat-cut electrode and 5-needle electrodes. 81 5.3 Impulse catheter models constructed in the CST Microwave Studio ® EM simulator. 84 [...]... generation compact pulsed power technology The combined research efforts on these issues enable the further development of pulsed power for biomedical, biophysical, and medicine applications 1 Chapter 1 Introduction 1.1 Pulsed Power Technology for Biomedical Applications Pulsed power refers to a technology of accumulating energy over a relatively long period of time and releasing it very quickly thus... electropermeabilization, and electroperturbation — overlapping pulsed electric field technologies 103 xi Abstract Pulsed power refers to a technology that is suited to drive applications requiring very large power pulses in short bursts Its recent emerging applications in biology demand compact systems with high voltage electric pulses in nanosecond time range The required performance of a pulsed power system... evaluated With comparison of simulation and experimental results, we further develop dielectric dispersion models for RPMI This thesis presents a set of strongly interdisciplinary studies based on pulsed power technology and towards biomedical applications Addressed issues include from fundamental materials studies to application engineering designs that are essential to next generation compact pulsed power. .. the instantaneous power Since the late John Chiristopher (Charlie) Martin and his colleagues developed the first modern pulsed power system at the Atomic Weapons Establishment, Aldermaston, U.K., in the 1960s [Martin, 1992], pulsed power has evolved to not only play an important role in defense, including homeland defense, but has evolved to become an important technology in the biomedical arenas as... level, hence expand our knowledge about cells [Schoenbach et al., 2004] 1.2 Research Issues in Compact Nanosecond Pulsed Power Technology To develop advanced ultra-short, high-field pulsed power technology for the biomedical applications of nanoelectropulses, the combined research efforts are required at three levels: efficient and robust devices at the component level, novel circuits and architecture... essential to bioelectrophysics studies Applying intense electric field is also a key to trigger intracellular effects Thus typically, spark gap and FET-type semiconductor switches appear in pulsed power systems in biomedical applications At present, the spark gap switch is still not replaceable when a compact pulsed power system is required to generate high voltage (> 10 kV) and high current (> 1 kA) with. .. thyristor, gate-turn-off thyristor (GTO), insulated gate bipolar transistor (IGBT), and metal-oxidesemiconductor field-effect transistor (MOSFET) These switches have the 7 advantages that when operated within specifications will live very long and have reduced house-keeping requirements [Schamiloglu et al., 2004] Table 1.1 summarizes parameters of typical switches used in pulsed power applications With. .. ultrashort electric pulses into tumors, a complicated “load” that varies in each patient Further more, reduction in the size and the number of components of pulsed power system is essential to make nanoelectropulse therapy actually become a reality [Vernier, 2004] 5 In addition to biomedical applications, advanced pulsed power technology also provides a powerful method to explore the electrical effects... Polymer/ceramic composites may see increasing applications in compact pulsed power systems in the near future 1.2.2 At system level A comapct nanosecond pulse generator is a useful research tool to explore impact of ultra short electropulses on biological cells, and to further seek applications in biomedical arenas However, commercial generators are rarely available to meet the requirements Large research efforts... key issue is the transmission of pulses without distortion Thus, catheters, the devices delivering nanopulses from pulse generation system to local tumors, requires high breakdown strength to hold peak voltages of kilovolts, broad frequency bandwidth to pass through nanosecond pulses without distortion, and a doctor-friendly interface to in vivo treat tumors with various shapes 16 The design of such . COMPACT NANOSECOND PULSED POWER TECHNOLOGY WITH APPLICATIONS TO BIOMEDICAL ENGINEERING, BIOLOGY, AND MEDICINE by Xianyue Gu A Dissertation Presented to the FACULTY. 2004]. 1.2 Research Issues in Compact Nanosecond Pulsed Power Technology To develop advanced ultra-short, high-field pulsed power technology for the biomedical applications of nanoelectropulses,. Introduction 1.1 Pulsed Power Technology for Biomedical Applications Pulsed power refers to a technology of accumulating energy over a relatively long period of time and releasing it very