Department: EECS - Electrical Engineering ![[clear]](close-x.png "Remove this limiter")
53 matches in the database.
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1.
Aloqlah, Mohammed.
A Headband-Integrated Wireless Accelerometer System for Real-Time Posture Classification and Safety Monitoring.
Degree: PhD, EECS - Electrical Engineering, 2010, Case Western Reserve University
► A real-time method using only accelerometers is developed for classification of basic…
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▼ A real-time method using only accelerometers is developed for classification of basic static/dynamic human postures, namely sitting, standing, bending, walking, lying, and running, as well as the dynamic states between them. Discrete wavelet transform (DWT) in combination with a fuzzy logic inference system (FIS) are the algorithmic basis underlying this method. A generic platform for continuously and unobtrusively monitoring human motion activity and safety is developed that is low power, inexpensive, and wearable. The platform is built around the following key components: a commercial low-power 10-million-instruction-per-second (MIPS) microcontroller; an IEEE 802.15.4 compliant 2.4 GHz wireless transceiver; sensors, including accelerometers, microphone, and humidity/temperature sensors. The sampling frequency is in the range of 20-100 Hz. The hardware architecture is a distributed modular implementation, occupying an area of less than one square inch. The hardware is integrated in a conventional wearable headband. Wirelessly transmitted data from a single three-axis accelerometer integrated into the headband is collected in real time on a laptop, and then analyzed to extract two sets of features necessary for posture/movement classification. The received acceleration signals is decomposed with DWT to extract the first set of features; any change of the smoothness of the signal that reflects a transition between postures is detected at the finer DWT resolution levels. FIS then uses the previous posture transition and the second set of features to choose one of eight different posture categories, namely sit, stand, lie on back, lie on left, lie on right, bend, walk, and run. Using the classifier in typical everyday activity among multiple users indicated more than 96.9%, 94.2%, 97.5% accuracy in detecting the static postures, walking, and running, respectively. Identifying the dynamic transitions among these steady postures achieved 92.6% accuracy. Furthermore, a simplified kinematic model is developed for estimation of the head static postures derived from the accelerometers’ output. A custom MATLAB-based PC software is developed for monitoring basic head movements. The “smart” headband is tested for indoor monitoring of human static postures and motion safety at home.
Advisors/Committee Members: Mehregany, Mehran.
Subjects: Electrical engineering
Keywords: POSTURE; ACCELEROMETER; Membership Function; Human Posture; Fuzzy; Microcontroller; Acceleration
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2.
Arora, Samarth.
Low Power Hybrid CMOS-NEMS for Microelectronics: Implementation in Implantable Pacemaker.
Degree: MS, EECS - Electrical Engineering, 2011, Case Western Reserve University
► Low power consumption is a primary goal in biomedical pacemaker design where…
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▼ Low power consumption is a primary goal in biomedical pacemaker design where it is crucial to increase the battery life of the device. Implantable pacemaker is a real time embedded system which is surgically placed in the body of the patient and is used to treat arrhythmia. We present a low power hybrid CMOS-NEMS implementation of the bandpass filter used within sense system of an implantable pacemaker and the NEMS Pacemaker Microcontroller. The approach is based on replacing the CMOS switches with NEMS switches in the hybrid CMOS-NEMS implementation. NEMS (Nano-Electromechanical Switches) offers unique characteristics in terms of turn-on voltage (≈ 1.5V), switching time (≈ 1ns), virtually zero leakage current, infinite ON current, and a small footprint size which enables low-power design. Our experimental results reveal significant power reduction for the hybrid CMOS-NEMS implementation in pacemakers.
Advisors/Committee Members: Saab, Daniel.
Subjects: Electrical Engineering
Keywords: NEMS (Nano-Electromechanical Switches); CMOS; Pacemaker; Low power
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3.
Azin, Meysam.
A Battery-Powered Multichannel Microsystem for Activity-Dependent Intracortical Microstimulation.
Degree: PhD, EECS - Electrical Engineering, 2011, Case Western Reserve University
► This project has developed an activity-dependent intracortical microstimulation (ICMS) system-on-chip (SoC) fabricated…
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▼ This project has developed an activity-dependent intracortical microstimulation (ICMS) system-on-chip (SoC) fabricated in a 0.35-µm two-poly four-metal CMOS process that converts extracellular neural spikes recorded from one brain region to electrical stimuli delivered to another brain region in real time in vivo. The 10.9-mm2 SoC incorporates two identical 4-channel modules, each comprising an analog recording front-end with total input noise voltage of 3.12 µVrms and noise efficiency factor (NEF) of 2.68, 5.9-µW 10b successive approximation register analog-to-digital converters (SAR ADCs), 12.4-µW digital processor for spike discrimination based on threshold crossing and two user-adjustable time-amplitude windows, and a programmable constant-current microstimulating back-end that delivers up to 94.5 µA with 6b resolution to stimulate the cortical tissue when triggered by neural activity. For autonomous operation, the SoC also integrates biasing and clock generation circuitry, frequency-shift-keyed (FSK) transmitter at 433 MHz, and dc-dc converter that generates a power supply of 5.05 V for the microstimulating back-end from 1.5 V. The fabricated SoC has been assembled and packaged on a miniature rigid-flex substrate together with a few external components for programming, supply regulation, and wireless operation. The resulting microdevice operates autonomously from a single 1.55-V battery, measures 3.6 cm x 1.3 cm x 0.6 cm, weighs 1.7 g (including the battery), and is capable of stimulating as well as recording the neural response to ICMS in biological experiments with anesthetized laboratory rats. Moreover, it has been interfaced with silicon microelectrodes chronically implanted in the cerebral cortex of an ambulatory rat and successfully delivers electrical stimuli to one cortical region when triggered by neural activity recorded from another distant cortical region with a user-adjustable spike-stimulus time delay. The spike-triggered ICMS is further shown to modulate the neuronal firing rate, indicating that it is physiologically effective.
Advisors/Committee Members: Mohseni, Pedram.
Subjects: Electrical Engineering
Keywords: Neural; ICMS; Spike; Recording of Neural; Circuit; Microdevice; Recording Front-End
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4.
Azizi, Farouk.
Microfluidic Chemical Signal Generation.
Degree: PhD, EECS - Electrical Engineering, 2009, Case Western Reserve University
► Chemical signals manifested by messenger molecules are omnipresent in the life sciences.…
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▼ Chemical signals manifested by messenger molecules are omnipresent in the life sciences. The ability to generate such chemical and biological signals artificially in microscale will be an enabling factor in probing, understanding, controlling and regulating complex biological systems. Microfluidics with many advantages such as consumption of small volume of sample and reagents, having a low cost, offer faster response and have a small footprint. In this dissertation, for the first time, the design, fabrication and testing of different architectures of microfluidic chemical concentration signal generators inspired by Digital to Analog Converters (DAC) are thoroughly studied. These chemical concentration signals generators are often called Concentration Digital to Analog Converter or C-DAC. The main idea is to generate binary weighted streams of chemical concentration signals and then select, direct and intermix those streams of concentration signals to the output based the value of digital input code generated by a computer program. Three different architectures which are developed in this research are based dilution networks, Pulse Code Modulators (PCM) and Multi-Plug Modulators (MPM). Modeling and simulation of microfluidic devices with hundreds of components at system level using conventional computational fluid dynamic (CFD) methods is very challenging and often impractical. A new lumped model which is inclusive of dispersion and convection is developed based on one-dimensional discretization of the convection-diffusion equation. The model which is implemented using Verilog-AMS is capable of tracking the transport of solvent and solute inside a microfluidic system using four dual-branch lumped nodal quantities of solvent pressure, solvent flow rate, solute concentration and solute current. The simulation results of Lab On Chip SIMulator tool (or simply LOCSIM) are in a very good agreements with the experimental results. The chemical concentration signal generators are used to design a combinatorial multicomponent plug mixer (CMPM) chip for drug discovery application. The CMPM chip is capable of generating a large number of mix ratios of four different components. The CMPM chip has used to study ribonucleotide reductase (RNR) protein-protein/protein-ligand interaction networks and was tested to produce fluorescent dye and dihydrofolate reductase NADPH/MX mixtures with plug lengths of 2 mm. In another application, a 1-bit PCM C-DAC chip (PCM chip) is used to chemically stimulate the nervous system in Aplysia Californica. In this application, chemical neurostimulation is performed to cereberal ganglion using the PCM chips and the neural activities are recorded extracellularly from buccal ganglion. The chip excitation with the agonist carbachol was successful in artificially inducing ingestive motor programs.
Advisors/Committee Members: Mastrangelo, Carlos.
Subjects: Electrical engineering
Keywords: Microfluidic, Micromixer, PDMS, Aplysia, Chemical Neurostimulation, Digital to Analog Converter, C-DAC, PCM, MPM, Dilution Network, Combinatorial Miromixer
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5.
Barnes, Andrew Charles.
Development of a Wire Bonding Process for Microsystems Fabricated From Polyvinyl Acetate - Nanocomposite.
Degree: MS, EECS - Electrical Engineering, 2011, Case Western Reserve University
► This thesis presents the development of a wire bonding process for MEMS-based…
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▼ This thesis presents the development of a wire bonding process for MEMS-based neural probes fabricated from a mechanically-dynamic, polyvinyl acetate – nanocomposite (PVAc-NC). A design of experiments approach was used to optimize the bonding parameters. Bonds on PVAc-NC with 200nm Au pads exhibited pull strengths > 7 gf, exceeding the military standard of 3 gf (MIL STD 883). When the PVAc-NC was exposed to DI water, the wire bonds failed to pass the military standard. Finite element modeling was performed to assist in the design of a more robust bond pad structure. Successful wire bonds were formed on substrates coated with Parylene-C, Ti and Au. These bonds were tested in both the dry and wet states but were unable to pass the military standard. Parylene was then applied to the wire bonded structures and the bond strength exceeded both MIL STD 883 and the maximum output of the force gauge (15gf).
Advisors/Committee Members: Zorman, Christian.
Subjects: Electrical Engineering
Keywords: Wire bonding; pull testing; DOE; dynamic polymer
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6.
Chaimanonart, Nattapon.
Adaptively Radio Frequency Powered Implantable Multi-Channel Bio-Sensing Microsystem for Untethered Laboratory Animal Real-Time Monitoring.
Degree: PhD, EECS - Electrical Engineering, 2009, Case Western Reserve University
► Genetic engineering of mice DNA sequences with real-time physiological monitoring has become…
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▼ Genetic engineering of mice DNA sequences with real-time physiological monitoring has become the most critical research tool for identifying genetic variation susceptibility to diseases. Genetically engineered mice have been widely used as research vehicles with their physiological data being highly important for advanced biological research. Animal-based research results are expected to make a significant impact in treating similar human diseases. Due to the small size of a laboratory mouse, a miniature, light-weight, wireless, batteryless, and implantable multi-channel bio-sensing microsystem is developed to capture real-time accurate biological signals from an untethered animal in its natural habitat, thus eliminating stress and post-implant trauma-induced information distortion. A reliable radio frequency (RF) powering technique based on inductive coupling allows the batteryless microsystem to be achieved with a small form factor. The RF powering technique widely employed in biomedical applications typically relies on a set of external coil and an implantable coil with a relatively fixed position to inductively couple an external RF energy to an implanted microsystem. However, the proposed microsystem is implanted in a freely roaming mouse; hence resulting in a drastically changing magnetic coupling as the mouse moves and tilts its position with respect to the external stationary coil. Therefore, an optimized remote RF powering system with an adaptive control capability is designed and implemented. The prototype sensing microsystem can detect two vital signals, electrocardiogram (EKG) and core body temperature, and wirelessly transmit the information to a nearby receiver by employing a low power CMOS integrated circuits design with a minimal number of off-chip components for a high-level system integration. The overall implant unit exhibits a dimension of 9 mm x 7 mm x 3 mm and a weight of 400 mg including a pair of stainless steel EKG electrodes. A low power 2 mm x 2 mm integrated circuit, consisting of an EKG amplifier, a proportional-to-absolute-temperature (PTAT) circuit, an RF power-level sensing circuit, an RF-to-DC power converter, an 8-bit analog-to-digital converter, a digital control unit, and a wireless transmitter, is designed and fabricated in a 1.5um CMOS process. An adaptively controlled external RF energy at 4 MHz is employed to ensure an on-chip stable 2V supply with a 156 uA current driving capability for the overall microsystem. This technique limits the on-chip voltage variation to ensure a proper electronic operation and reliable implant power, and also minimizes the external power dissipation; hence the environment temperature rise. Untethered laboratory mice implant study demonstrates the microsystem capability of capturing real-time EKG and core body temperature information under a wireless and batteryless condition. Other biological sensing channels such as blood pressure and activity signals can be potentially integrated with the system architecture.
Advisors/Committee Members: Young, Darrin.
Subjects: Electrical engineering
Keywords: Remote RF Powering System; Wireless Bio-Sensing Electronics; Electrocardiogram; Implantable Microsystems; CMOS Integrated Circuits; Core Body Temperature
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7.
Cong, Peng.
WIRELESS BATTERYLESS IN VIVO BLOOD PRESSURE SENSING MICROSYSTEM FOR SMALL LABORATORY ANIMAL REAL-TIME MONITORING.
Degree: PhD, EECS - Electrical Engineering, 2008, Case Western Reserve University
► Genetically engineered small laboratory animals with in vivo real-time physiological signals monitoring…
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▼ Genetically engineered small laboratory animals with in vivo real-time physiological signals monitoring are ultimately crucial for system biology research to identify genetic variation susceptibility to various diseases and to develop effective treatment methods for similar human diseases. Blood pressure is one of the most important vital signals used in such research. However, there is no adequate solution for its chronic blood pressure monitoring to date. By merging MEMS technology and low power CMOS integrated circuits design through a high level system integration together with a conventional molding-based packaging technique, miniature, light-weight, wireless, batteryless, less-invasive, and implantable blood pressure sensing microsystems have been demonstrated for untethered small laboratory animals real-time monitoring. These critical features of the microsystem greatly suppress stress and post-implant trauma-induced information distortion. The proposed microsystem employs a miniature instrumented elastic sensing cuff, wrapped around a blood vessel, for blood pressure monitoring. The blood pressure is coupled into the sensing cuff caused by the vessel expansion and contraction. The microsystem can detect the pressure signal and wirelessly transmit the information to a nearby receiver with an adaptive RF powering capability to ensure a stable system power supply. The sensing technique avoids vessel penetration and substantially minimizes vessel restriction due to the soft cuff elasticity, thus attractive for long-term implant. A MEMS capacitive pressure sensor is designed and fabricated for its low temperature dependence, time stability, and zero DC power consumption. The integrated electronics consisting of a low power low-noise correlated-double-sampling capacitance-to-voltage converter, an 11-bit cyclic ADC, an adaptive RF powering system, an oscillator-based transmitter, and digital control circuitry have been designed and fabricated in a 1.5µm CMOS process. The prototype system achieves a 10-bit system resolution with 300µW power consumption. The ASIC and the MEMS sensor are interfaced with a 5mm-diameter RF powering coil over a thin flexible substrate and packaged with the blood pressure sensing cuff. The microsystems designed for laboratory rats and mice monitoring exhibit a weight of 430mg and 130mg, respectively. Untethered laboratory animals implant study demonstrates the microsystem capability of capturing real-time high-fidelity blood pressure information under a wireless and batteryless condition. Other bio-sensing channels such as core body temperature and EKG can be integrated into the prototype system architecture.
Advisors/Committee Members: Young, Darrin.
Subjects: Electrical engineering
Keywords: Microsystem, Mixed-signal Integrated circuit design, Low power Low noise circuit, Medical device, implantable device, RF powering, wireless data telemetry
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8.
Deal, Aaron M.
Hybrid Position/Natural Admittance Control for Laparoscopic Surgery.
Degree: MS, EECS - Electrical Engineering, 2012, Case Western Reserve University
► Minimally-invasive surgery, notably with the use of robots, is a rapidly growing…
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▼ Minimally-invasive surgery, notably with the use of robots, is a rapidly growing area due to the potential benefits of faster recovery times and lower risk of infection relative to conventional surgery. However, current practice is slow and cumbersome, motivating research in more competent and more efficient robotic surgery. Current research includes robotic assistants that could perform long, repetitive tasks such as suturing. For these assistants, two controllers were developed that obey the portal constraint while maintaining a compliant tip. The first controller was a variation of Natural Admittance Control. The second merged Natural Admittance Control and hybrid force/position control. The results showed that the hybrid controller is 3.5 times better at conforming to the portal kinematic constraint than the Natural Admittance Control algorithm.
Advisors/Committee Members: Newman, Wyatt.
Subjects: Robotics
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9.
Ehret, Steven J.
Instrumentation for anodization and in-situ testing of titanium alloys for capacitor anodes.
Degree: MS, EECS - Electrical Engineering, 2012, Case Western Reserve University
► The development of smaller, more efficient energy storage devices is needed in…
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▼ The development of smaller, more efficient energy storage devices is needed in industries ranging from consumer electronics to the automobile industry. One such device is the capacitor, which stores electrical energy in the form of an electric field. This electric field is established by the separation of charge between two conductors with an insulating dielectric between them. In electrolytic capacitors, this dielectric is an anodic oxide that is grown directly on the anode of the capacitor in an electrochemical process known as anodization. Research to develop electrolytic capacitors with increased power and energy densities using new materials and processes to create the capacitor anodes require the ability to record voltage and current data during the anodization process. This thesis presents the design of custom instrumentation that provides researchers with a platform to control the anodization parameters via a computer interface and record the current and voltage data necessary to aid in the development of advanced materials for capacitor anodes to a computer hard drive for later viewing and analysis. Initial results and performance analysis are also included.
Advisors/Committee Members: Merat, Francis.
Subjects: Electrical Engineering
Keywords: Titanium anodization; instrumentation for anodization
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10.
Emelko, Glenn A.
A New Algorithm for Efficient Software Implementation of Reed-Solomon Encoders for Wireless Sensor Networks.
Degree: PhD, EECS - Electrical Engineering, 2009, Case Western Reserve University
► With the recent introduction and development of ad-hoc wireless sensor networks, and…
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▼ With the recent introduction and development of ad-hoc wireless sensor networks, and other miniature or low-power communications systems, high performance at a low cost is a key critical factor. Reliable data transmission from these wireless sensors is necessary, especially if the sensor end-points are transmit-only type devices. Error correction codes may be used to improve reliability of the transmission, in many instances improving the operating margin by 6dB or more (depending on the correcting power of the code). Presented is an algorithm for highly efficient, compact Reed-Solomon error correction encoder, realized entirely in software. This improved encoding algorithm takes between 31 and 62 CPU cycles on an 8-bit processor to encode each symbol, requires under 60 words of ROM and only a single RAM location. Able to encode data at over 50K symbols per second on a 4 MIPS processor, this algorithm is well suited for low cost wireless sensor applications.
Advisors/Committee Members: Merat, Francis.
Subjects: Communication; Computer science; Electrical engineering; Mathematics
Keywords: Algorithm Wireless Sensor Network Reed Solomon Encoder Error Correction Software
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11.
Faley, Katherine A.
Control System Design for Offshore Wind Turbines Under Extreme Icy/Tide-Variable Weather Conditions.
Degree: M. Eng., EECS - Electrical Engineering, 2011, Case Western Reserve University
► This document presents the dynamic modeling and analysis of offshore wind turbines…
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▼ This document presents the dynamic modeling and analysis of offshore wind turbines operating under icy and tide-variable weather conditions, and the design of an advanced control system able to reduce the potential mechanical fatigue of the turbines in these conditions. By examining the frequency response and the model uncertainty of the system plants, there is a noticeable effect from the incorporated effects of ice and tide that increase the amplitude of tower vibrations at some particular frequencies, which creates greater mechanical fatigue. The novel torque control system is designed by varying the generator torque in the above rated wind speed region, while meeting the thermal specifications of the generator and converters and maintaining an average torque over time that continues to produce the rated power of the turbine. The velocity of the nacelle movement due to the wind turbulences decreases, thus reducing the associated mechanical fatigue. The model and the new control strategy are validated by observing the Bode diagrams of the plant systems and with a realistic time-domain nonlinear simulator. Part of this thesis was summarized in a paper that was accepted to be presented at the ASME 2011 International Mechanical Engineering Congress and Exposition in Denver in November 2011 [16].
Advisors/Committee Members: Garcia-Sanz, Mario.
Subjects: Electrical Engineering; Energy
Keywords: Wind Turbines; Control; QFT; Offshore
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12.
Farnsworth, Bradley David.
Wireless Implantable EMG Sensing Microsystem.
Degree: MS, EECS - Electrical Engineering, 2010, Case Western Reserve University
► An implantable wireless electromyogram sensing microsystem is developed for control of powered…
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▼ An implantable wireless electromyogram sensing microsystem is developed for control of powered prostheses. RF powering and wireless data link enable real-time wireless operation. EMG signals are interfaced with a capacitively-coupled differential amplifier with 1 kHz bandwidth and an input-referred voltage noise power spectral density of 78 nV/√(Hz). The EMG signal is digitized by an on-chip 11 bit cyclic ADC. A Class-E amplifier operating at 8 MHz drives a 2-cm spiral coil, inductively coupled to an implantable 6-mm spiral coil. RF energy is rectified and regulated on-chip to produce stable 2.1V and 2.7V supplies. Manchester-encoded EMG data are transmitted by PSK modulation. The ASIC fabricated in the AMI 1.5μm CMOS process occupies 2.2x2.2 mm2 and dissipates 350 μW from RF powering. The system achieves 9.35 ENOB under battery powering and 8.6 ENOB under RF power, equivalent to an input detectable signal of 5.4 μVRMS and 9 μVRMS, respectively. In vivo testing shows a background EMG signal of 20 μVRMS, limiting system sensing resolution.
Advisors/Committee Members: Young, Darrin.
Subjects: Biomedical research; Electrical engineering; Engineering; Rehabilitation
Keywords: wireless; implantable; emg; electromyogram; moderate; inversion; subthreshold; class-e; rf powering; psk; phase shift keying; inductive coupling; near field; low power
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13.
Feng, Chao.
GREY-MODEL BASED ICE PREDICTION SENSOR SYSTEM ON WIND TURBINE SYSTEM.
Degree: M. Eng., EECS - Electrical Engineering, 2012, Case Western Reserve University
► Ice is an important factor for wind turbine system health monitoring. Ice…
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▼ Ice is an important factor for wind turbine system health monitoring. Ice should be predicted and removed before it forms on the blades. If ice forms on the axle, it will give a friction force on the axle and damage the electrical system. My objective is to design and implement an ice detection sensor system to prevent the ice forming on wind turbine. Several fiber optic sensors are chosen to measure side parameters, input to a grey-model based prediction module to get the predicted values, and send them to LEWICE system to predict the ice shape.
Advisors/Committee Members: Papachristou, Chris.
Subjects: Engineering
Keywords: Key Word: fiber optic sensors, side-parameter analysis, grey model
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14.
Fu, Michael J.
Computational Models and Analyses of Human Motor Performance in Haptic Manipulation.
Degree: PhD, EECS - Electrical Engineering, 2011, Case Western Reserve University
► Haptic interaction refers to interactivity with an environment based on the sense…
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▼ Haptic interaction refers to interactivity with an environment based on the sense of touch. Haptics is a critical mode of human interface with real or virtual environments, as it is the only active form of perception. All other senses are passive and cannot directly act upon an environment. Haptic interface devices connect users to real or virtual environments through the modality of touch and associated sensory feedback. As the user interacts with environments through the haptic system, it alters the user's perception and motor control, which can affect task performance. Therefore, understanding a haptic system's effects on the sensory-motor system and the implications of these interactions on task performance is important for the design of effective haptic interface systems. This dissertation focused on characterization, modeling, and analysis of human motor performance in the context of stylus-based haptic interface devices. The current work combined human psychophysics experiments with analysis methods from system theory to model and study several aspects of human haptic interaction. The first contribution of this work was the identification of 3D linear dynamics and variability models for the arm and hand configured in a stylus grip. The literature contains many human arm dynamics models, but lacks detailed associated variability analyses. Without them, variability is modeled in a very conservative manner, leading to less than optimal controller and system designs. The current work not only presented models for human arm dynamics, but also developed inter and intra-subject variability models from human experiments. The second contribution of this work was the analysis of 3D point-to-point Fitts' reaching task in both real and virtual environments in order to determine the effect of visual field and haptic workspace co-location on task performance. A key finding was the significant decrease observed in end-point error for tasks performed in a co-located virtual environment. The results also confirmed cyclic performance degradations due to rotational visuo-haptic misalignments for a wide variety of task difficulties. These findings expanded important understanding regarding the behavior of the human operator, which is arguably the most variable element in any haptic interface system.
Advisors/Committee Members: Cavusoglu, M. Cenk.
Subjects: Biophysics; Electrical Engineering; Systems Science
Keywords: haptics; haptic interfaces; virtual reality; virtual environments; human operator models; haptic devices; Fitts' Task
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15.
Hess, Allison Elizabeth.
Integration of Process-Incompatible Materials for Microfabricated Polymer-Based Neural Interfaces.
Degree: PhD, EECS - Electrical Engineering, 2011, Case Western Reserve University
► This dissertation presents the development of microfabrication processes for the integration of…
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▼ This dissertation presents the development of microfabrication processes for the integration of process-incompatible, dissimilar materials in MEMS devices with application to neural interfaces for long-term implantation. Micromachining techniques were developed for a novel, mechanically-dynamic, chemo-responsive polymer nanocomposite based on a poly(vinyl acetate) matrix with embedded cellulose nanofibers designed to address issues related to the mechanical mismatch between the neural probe and cortical tissue. Microtensile testing was performed to assess the mechanical properties of laser-patterned nanocomposite microstructures. Within 3-7 minutes of immersion in DI water, the nanocomposite displayed a reduction in Young’s modulus by a factor of 140-200, from 1.2-3.4 GPa to 4.9-22 MPa, depending upon the cellulose nanofiber source and concentration. A comparable reduction in Young’s modulus was measured for samples that had been implanted in a rat cortex, suggesting this material can penetrate through the pia without buckling, but then softens and better matches the mechanics of cortical tissue. A process utilizing a parylene moisture barrier was developed to fabricate nanocomposite-based intracortical probes with integrated thin-film metal electrodes and interconnects. The electrode impedance was found to be 95.0 + 4.8 kΩ for an electrode 6000 µm2 in area. To develop a microfabricated neural array technology with on-board recording, stimulation and chemical sensing capabilities, a process was developed to integrate semi-metallic diamond microelectrodes into a flexible polymer substrate. Diamond-on-polymer microelectrode arrays were fabricated using a “diamond-first” fabrication process whereby the diamond electrodes were first grown on a Si/SiO2 substrate, followed by the deposition and patterning of a polynorbornene capping layer, thin-film metal interconnects, and a polynorbornene substrate layer. A chemical release process in 49% HF was used to transfer the diamond from the Si substrate to the polymer substrate. Ohmic contact was made to diamond microelectrodes using Cr/Au metallization, without requiring an annealing step. Current pulse testing demonstrated potential for neural stimulation with diamond microelectrodes. The electrode impedance at 1 kHz was found to range from 300 kΩ to 8 MΩ, indicating that there are some electrodes suitable for neural recording. Finally, electrochemical detection of 100 µM dopamine in saline was achieved with a diamond-on-polymer electrode.
Advisors/Committee Members: Zorman, Christian.
Subjects: Biomedical Engineering; Electrical Engineering
Keywords: MEMS fabrication; mechanically-dynamic; polymer nanocomposite; diamond-on-polymer; neural interfaces
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16.
Howe, Daniel S.
Electronics and Communication Technology for a Surface Stimulation Device.
Degree: MS, EECS - Electrical Engineering, 2009, Case Western Reserve University
► The electronics for a wearable surface stimulation device (SSD) used for the…
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▼ The electronics for a wearable surface stimulation device (SSD) used for the treatment of chronic wounds is presented. The device consists of a flexible polyimide substrate with platinum electrodes and a small, battery-powered circuit board that provides up to seven days of user-programmable stimulation.A boost converter circuit generates stimulation pulses up to 20 mA. Special control algorithms implemented in a microcontroller are used to minimize power consumption and extend battery life. High-voltage interface circuits and a tissue impedance measurement function are used to control the stimulation pulse timing and current. Custom software has been written to communicate with the SSD through an infrared link. This communication interface allows the user to program stimulation parameters, read out experiment measurements, and utilize on-board diagnostic tools. The electrical performance has been measured and compared to calculations and simulation results. The results of a preliminary animal experiment are also reported.
Advisors/Committee Members: Garverick, Steven.
Subjects: Electrical engineering
Keywords: Boost converter; SSD; converter; Microcontroller; Boost; STIMULATION; ADC
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17.
Hsu, Ming-Hsuan.
MICROPROCESSOR-COMPATIBLE NEURAL SIGNAL PROCESSING FOR AN IMPLANTABLE NEURODYNAMIC SENSOR.
Degree: MS, EECS - Electrical Engineering, 2009, Case Western Reserve University
► The development, design, and test results for a neural signal detection and…
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▼ The development, design, and test results for a neural signal detection and compression algorithm are presented, including Matlab implementation, hardware test using a PIC microcontroller, and simulation results and layout of a VLSI implementation. The algorithm has achieved an average compression ratio of 20:1 in the sample data, 1.6 Mbit/sec to 80 kbit/sec. The quality of the Matlab simulation result has been proven by manual evaluation by an expert in neural signals. The PIC implementation is based on the work of a senior project, which was shown to produce real-time results that match the simulation result in Matlab. Finally, a verilog version of the algorithm was implemented and simulation test results are presented. The verilog version uses a standard digital cell library to produce a VLSI layout in 0.5-CMOS process.
Advisors/Committee Members: Garverick, Steven.
Subjects: Biology; Biomedical research; Electrical engineering
Keywords: Neural Signal Processing; Neural Spike Detection, Compression, Reconstruction
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18.
Hudson, Richard Earl.
Semi-Supervised Visual Texture Based Pattern Classification.
Degree: PhD, EECS - Electrical Engineering, 2012, Case Western Reserve University
► Automated visual classification becomes increasingly practical as cameras and computational power become…
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▼ Automated visual classification becomes increasingly practical as cameras and computational power become more accessible. Already, many existing automated visual inspection methods are competitive with human levels of performance. This dissertation presents a semi-supervised visual classification algorithm based on Independent Component Analysis, Yan Karklin’s Hierarchical Bayesian Model algorithm and Bayes’ Theorem. Several problems of current interest, both in industry and the research literature, are used as example applications: mobile robotics, industrial inspection and mammography. Results are given demonstrating the effectiveness of this method.
Advisors/Committee Members: Newman, Wyatt.
Subjects: Electrical Engineering
Keywords: ICA Image Processing; Image Segmentation; Bayesian Optimal Machine Vision
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19.
Hughes, Bradley Evan.
A Navigation Subsystem for an Autonomous Robot Lawn Mower.
Degree: MS, EECS - Electrical Engineering, 2011, Case Western Reserve University
► This thesis describes a cost effective, accurate, and precise electronic navigation system…
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▼ This thesis describes a cost effective, accurate, and precise electronic navigation system which is suitable for outdoor commercial mobile robots. The hardware design of the system incorporates commercial off the shelf Global Positioning System receiver modules and support electronics. The software design of the system makes use of an open source positioning library to enable Real Time Kinematic satellite positioning. The designed navigation system has been integrated with a preexisting mobile robot platform, an autonomous robot lawn mower, which includes a set of reference sensors to provide accurate robot pose information. The reference platform is used to quantitatively evaluate the performance of the new cost effective system. A degradation factor of 1.7 in terms of positional accuracy is traded off in favor of achieving a cost savings factor of about thirty.
Advisors/Committee Members: Quinn, Roger.
Subjects: Computer Engineering; Electrical Engineering; Robotics; Robots
Keywords: mobile robot; autonomous guided vehicle; global positioning system; navigation system; control system; robot lawn mower; consumer product automation; low cost navigation
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20.
Karnick, David A.
Miniaturization of Folded Slot Antennas through Inductive Loading and Thin Film Packaging.
Degree: MS, EECS - Electrical Engineering, 2011, Case Western Reserve University
► Miniaturization of RF devices through reactive loading and thin film packaging is…
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▼ Miniaturization of RF devices through reactive loading and thin film packaging is investigated. Impedance matching of a Wilkinson power divider with inductive loading is used to formulate relationships between load inductance, operating frequency, transmission line length, and line impedance. The resonant frequency of a folded slot antenna (FSA) is shown to decrease with the addition of inductive loading. This process can be reversed to create a physically smaller antenna with the same resonant frequency. FSAs with inductive and capacitive loading in combination are also investigated, but no benefit is found to the addition of capacitors. Amorphous SiC deposited by sputtering is investigated as a thin film packaging material for RF applications. Various packaging qualities are tested, including chemical resistance, conformality, adhesion, dielectric constant, and effect on the operation of the packaged device. It is shown that, except for lack of conformality, sputtered SiC is appropriate for packaging RF devices.
Advisors/Committee Members: Zorman, Christian.
Subjects: Electrical Engineering
Keywords: folded slot antenna; FSA; miniaturization; inductive loading; silicon carbide; SiC; packaging
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21.
Kirsch, Matthew Robert.
Signal Processing Algorithms for Analysis of Categorical and Numerical Time Series: Application to Sleep Study Data.
Degree: MS, EECS - Electrical Engineering, 2010, Case Western Reserve University
► In this thesis, novel entropy-based measures are developed to quantify the fragmentation…
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▼ In this thesis, novel entropy-based measures are developed to quantify the fragmentation of an individual categorical time series and the coupling strength of two categorical time series. Existing entropy-based measures are also shown to be well suited for the same task. These measures are applied to the analysis of categorical time series derived from sleep study data. Specifically, fragmentation of the hypnogram categorical time series of sleep stages, fragmentation of the breathing categorical time series of oxygen desaturation events, and coupling between the hypnogram and breathing categorical time series is quantified and the relationship between these measures and the diagnostic outcomes of hypertension and obstructive sleep apnea is investigated. Additionally, electroencephalogram (EEG) activity during sleep is explored by analyzing the distribution of power in various frequency bands throughout the night using summary statistics and a histogram entropy measure computed using the maximum-entropy histogram binning procedure developed in this thesis.
Advisors/Committee Members: Loparo, Kenneth.
Subjects: Biomedical research; Engineering
Keywords: categorical time series; signal processing; spectral entropy; conditional entropy; histogram entropy; sleep dynamics; sleep fragmentation
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22.
Kourennyi, Dmitri Dmitrievich.
Customer Tracking Through Security Camera Video Processing.
Degree: MS, EECS - Electrical Engineering, 2011, Case Western Reserve University
► Knowledge of consumer walking paths in a retail store can be useful…
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▼ Knowledge of consumer walking paths in a retail store can be useful in positioning of advertising or layout of products. Currently a number of methods are used for such tracking, including wireless telemetry or image processing with a video camera. In this research, image processing techniques of a security camera feed are used to identify the body of consumers and track them within the image space. The tracked position data can be used to track when consumers enter or exit a given area, which can be predefined by the user using a simple GUI. The results show that the algorithm concept is successful at tracking subjects, and properly resolving certain situations that would prove difficult for other image-based methods. Implementation of such a system would involve low cost and minimal equipment acquisition, making it attractive to retail stores.
Advisors/Committee Members: Loparo, Kenneth.
Subjects: Electrical Engineering
Keywords: video tracking; security camera; motion detection; retail customer tracking
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23.
Kulp, William R.
Robotic Person-Following in Cluttered Environments.
Degree: MS, EECS - Electrical Engineering, 2012, Case Western Reserve University
► This thesis presents the development of hardware and software elements for the…
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▼ This thesis presents the development of hardware and software elements for the task of a mobile robot following a specific person through an obstacle-filled room. Person-tracking is performed via a Microsoft Kinect placed on a panning mount. A sensor fusion algorithm combines information from the Kinect with a face detector, a LIDAR-based leg detector, and a color signature. A dynamic replanning system was created to allow the robot to converge on targets moving through space navigable by the robot. Performance data is presented for the experimental system.
Advisors/Committee Members: Newman, Wyatt.
Subjects: Computer Science; Electrical Engineering; Robotics; Robots
Keywords: robotics; person-tracking; person-following; mobile robot; kinect; path planning
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24.
Lachhman, Shem Benjamin.
Roller-Cast Poly-Dimethylsiloxane as a Non-Hermetic Encapsulant for MEMS Packaging.
Degree: MS, EECS - Electrical Engineering, 2012, Case Western Reserve University
► This thesis describes the development of a roller-casting process for multi-layered poly-dimethylsiloxane…
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▼ This thesis describes the development of a roller-casting process for multi-layered poly-dimethylsiloxane films to be used as an encapsulant for implantable MEMS. Accelerated lifetime studies were conducted at 40°C and 85°C in saline solution on sixteen samples each containing eight interdigitated electrode arrays and encapsulated with Dow Corning MDX4-4210 Biomedical Grade Elastomer. A custom environmental testing system designed for long-term, unmonitored testing was built to acquire resistance measurements. Select samples received surface treatments prior to PDMS deposition to enhance adhesion and were evaluated by pull-off tests before and after soak testing. Test results show lifetimes up to 40 days for samples tested at 85°C. Samples in 40°C saline solution are still under test with no device failures after 68 days. The estimated maximum lifetime of packages made using the roller casting method based on previously published data is 5.5 years at physiological temperature (37°C) and 22.2 years at 25°C.
Advisors/Committee Members: Zorman, Christian.
Subjects: Electrical Engineering
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25.
Laotaveerungrueng, Noppasit.
A High-Voltage, High-Current Multi-Channel Arbitrary Waveform Generator ASIC for Neural Interface and MEMS Applications.
Degree: PhD, EECS - Electrical Engineering, 2011, Case Western Reserve University
► A highly flexible waveform generator is desired for applications from neural stimulation…
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▼ A highly flexible waveform generator is desired for applications from neural stimulation to microelectromechanical systems (MEMS) actuator interfaces. The demand for such application includes multi-channel outputs, various waveform shapes, and different output modes. This thesis presents a high-voltage, high-current arbitrary waveform generator application-specific integrated circuit (ASIC) based on 0.35-µm high-voltage CMOS technology. The chip has 16 independently-controlled biphasic output channels. The output driver is capable of delivering a current up to 5.04 mA with up to 20 V voltage compliance, and a voltage up to 9.45 V with more than 5 mA output current, in current- and voltage-controlled modes, respectively. With an integrated 5k-bit memory, the chip can generate any arbitrary shape of waveform with up to 1 MHz clock frequency. Of particular interest to the neural stimulation applications, the chip can provide adjustable interphase delay period, reverse pulse phase, and charge-balancing phase for safe and efficient stimulation. The charge-balancing approach that shorts all stimulating electrode pairs together after a long sequence of stimulation cycles is also implemented to prevent damages on both electrode and targeted tissue area. The chip has been successfully interfaced and tested with a three-dimensional microfabricated electrode developed in our laboratory for targeted deep brain stimulation. Proof of concept for current steering in vitro in both current and voltage modes, as well as in an in vivo experiment on an anesthetized rabbit, are demonstrated. For various MEMS applications, a chip with multiple outputs providing both current- and voltage-controlled arbitrary waveforms can accommodate the needs of driving resistive and capacitive devices, as well as multiple sequential waveforms for actuators such as micromotors. An experiment on a silicon carbide flow sensor developed in our laboratory validates the concept of using the chip as a function generator. The chip is configured to supply a 5 mA constant current and a 4.5 mA current pulse to the heater of the flow sensor in order to characterize flow measurement output and response time, respectively. The foregoing provides an on-chip solution for an arbitrary function generator that can be monolithically fabricated with other circuitry. Based on its configuration, this chip is an ideal solution for various applications, ranging from an on-chip arbitrary function generator to a multi-channel neural stimulator.
Advisors/Committee Members: Mehregany, Mehran.
Subjects: Electrical Engineering
Keywords: Neural Stimulation Circuits; Implantable Microsystems; CMOS Integrated Circuits; Charge-balancing Circuits; Neural Stimulator
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26.
Lekas, Michael S.
A MAGNETIC PHASED ARRAY ANTENNA FOR COMMUNICATION WITH IMPLANTED BIOMEDICAL DEVICES IN SMALL ANIMALS.
Degree: MS, EECS - Electrical Engineering, 2009, Case Western Reserve University
► A novel antenna system for short-range wireless communications with implantedbiomedical devices is…
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▼ A novel antenna system for short-range wireless communications with implantedbiomedical devices is proposed. Wireless signals are received through the electromagnetic near-field using a group of antennas rather than one. Signals from each antenna are phase aligned and summed to boost the overall received signal. The receiving array consists of two antennas, spanning a rectangular area of 10 cm by 18 cm. A phase shifting circuit, capable of altering signal phase by 251°, was designed for use in phase alignment. A phase detection and control circuit was designed to assess the difference in phase between received signals, and to generate a control signal for the phase shifting circuit, in order to dynamically align phases. The loop bandwidth of the control system is approximately 10 Hz. Each receiving channel of the system has a noise spectral density of 0.41 nV/RT Hz.
Advisors/Committee Members: Garverick, Steven.
Subjects: Electrical engineering; Electromagnetism; Engineering
Keywords: magnetic; phased array; biomedical telemetry
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27.
Lewis, Evan.
KUDDLER.
Degree: MS, EECS - Electrical Engineering, 2010, Case Western Reserve University
► This thesis discusses the design, development and, construction of a device to…
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▼ This thesis discusses the design, development and, construction of a device to be deployed in the Neonatal Intensive Care Unit (NICU) to provide health and developmental benefits to premature infants in an incubator setting. The device, hereafter referred to as KUDDLER, provides customized access to Kangaroo Care for premature infants in the NICU when they cannot be with their mothers. One of the important features of KUDDLER is that it can be customized to the unique respiratory and heartbeat patterns of the mother. During setup of the unit, the mother’s heartbeat and respiration signals are recorded and stored in a computer for future use. The KUDDLER is then placed in an incubator and the infant is placed on top on the device. The KUDDLER is operated from a computer that is located on a cart and oscillates up and down with the same respiratory rhythm that would be experienced in direct contact with the mother and a speaker on the back of the device provides the mother’s heartbeat sounds. The KUDDLER also retains the heat of the surrounding incubator to provide proper warmth for the neonate.
Advisors/Committee Members: Loparo, Kenneth.
Subjects: Electrical engineering
Keywords: premature infant; medical device; NICU; biometrics; mother; Kangaroo Care
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28.
Lien, E-Jen.
EFFICIENT IMPLEMENTATION OF ELLIPTIC CURVE CRYPTOGRAPHY IN RECONFIGURABLE HARDWARE.
Degree: MS, EECS - Electrical Engineering, 2012, Case Western Reserve University
► Elliptic curve cryptography (ECC) has emerged as a promising public-key cryptography approach…
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▼ Elliptic curve cryptography (ECC) has emerged as a promising public-key cryptography approach for data protection. It is based on the algebraic structure of elliptic curves over finite fields. Although ECC provides high level of information security, it involves computationally intensive encryption/decryption process, which negatively affects its performance and energy-efficiency. Software implementation of ECC is often not amenable for resource-constrained embedded applications. Alternatively, hardware implementation of ECC has been investigated – in both application specific integrated circuit(ASIC) and field programmable gate array (FPGA) platforms – in order to achieve desired performance and energy efficiency. Hardware reconfigurable computing platforms such as FPGAs are particularly attractive platform for hardware acceleration of ECC for diverse applications, since they involve significantly less design cost and time than ASIC. In this work, we investigate efficient implementation of ECC in reconfigurable hardware platforms. In particular, we focus on implementing different ECC encryption algorithms in FPGA and a promising memory array based reconfigurable computing framework, referred to as MBC. MBC leverages the benefit of nanoscale memory, namely, high bandwidth, large density and small wire delay to drastically reduce the overhead of programmable interconnects. We evaluate the performance and energy efficiency of these platforms and compare those with a purely software implementation. We use the pseudo-random curve in the prime field and Koblitz curve in the binary field to do the ECC scalar multiplication operation. We perform functional validation with data that is recommended by NIST. Simulation results show that in general, MBC provides better energy efficiency than FPGA while FPGA provides better latency.
Advisors/Committee Members: Bhunia, Swarup.
Subjects: Electrical Engineering
Keywords: Elliptic curve cryptography; ECC; MAHA; MBC; FPGA; low-power; encryption; security
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29.
Lin, Chia-Hua.
A Microfabricated Deep Brain Stimulation Electrode.
Degree: MS, EECS - Electrical Engineering, 2009, Case Western Reserve University
► This work presents a novel 4-sided, 16-channel deep brain stimulation electrode with…
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▼ This work presents a novel 4-sided, 16-channel deep brain stimulation electrode with a flexible extension lead for connectivity with pulse generation electronics. The 3-dimensional electrode enables steering the current field circumferentially. The electrode is fabricated in pieces by microfabrication techniques; the pieces are then assembled mechanically, after which the lead is connected. The electrode is modeled by finite element analysis and tested in vitro to validate the design concept, i.e., targeted stimulation. With monopolar and bipolar configurations, the electric potential in front of the activated site is at least five times larger than that on the other not-activated sides within a 3 mm radius. The resistance of each channel is also measured. Finally, a pull test is performed to evaluate the mechanical strength of the epoxy used to attach the lead to the electrode. The samples withstood a force of 8.66 g at a 60° angle, thus exhibiting high robustness.
Advisors/Committee Members: Mehregany, Mehran.
Subjects: Biomedical research; Electrical engineering
Keywords: bioMEMS; Deep Brain Stimulation; internal electrode; MEM; microfabrication; DBS
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30.
Lin, Feng-Hsu.
An Integrated Rectifier/Regulator for a Wireless Battery Charging System.
Degree: MS, EECS - Electrical Engineering, 2009, Case Western Reserve University
► A wirelessly powered charging system for use in implanted biomedical applications is…
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▼ A wirelessly powered charging system for use in implanted biomedical applications is proposed. A sinusoidal ac voltage received through the magnetic inductive link, which is driven by a Class-E power amplifier, is input to an active rectifier, which converts it to an unregulated dc supply voltage. A regulator circuit then provides dc-dc conversion to produce a specific dc voltage to charge a miniature, bio-compatible pin-type Lithium-Ion battery. An integrated circuit, comprised of the active rectifier and the regulator, was designed to meet the requirements of the system and was fabricated in the AMI 0.5-μm CMOS process. Tests were performed to verify the functionality and performance of the circuit.
Advisors/Committee Members: Garverick, Steven.
Keywords: RECTIFIER/REGULATOR; Voltage; VAC; Active Rectifier; VSUP; Vp
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