Fluid behavior at the microscale exhibits large surface to volume ratios increasing the significance of interfacial phenomena. We have studied two microfluidic phenomena that utilize interplay between microstructure and chemical composition. The first one causes liquid droplets to roll off from surfaces with a very high contact angle. This phenomenon is called superhydrophobic behavior, can be controlled by several tuning parameters. The second one changes the wettability of liquids on a dielectric coated surface with electric potential. The experimental studies were done by first fabricating an ordered array of glass nanocones. Fiber drawing and differential glass etching processes were used to produce cone like structures with lattice constant of 40 μm down to 1.6 μm. The superhydrophobic behavior was first studied and modeled in a series of nanocone wafers of increasing aspect ratio from .3 to 15. The characterization was done by the measurement of the contact and rolling angles. The Wenzel to Cassie transition of wetting states was observed. The contact angles were calculated by using the ‘axisymmetric drop shape analysis’ approach. Next, the study of the electrowetting behavior of two broad categories of structured surfaces was done. One was a low aspect ratio surface exhibiting Wenzel wetting and the other was a high aspect ratio surface exhibiting Cassie wetting. The device for experimental study was prepared by coating additional layers, which included conductive gold and dielectric Parylene-C coatings. Studies were done using silicone oil and air as the ambient medium. Images of drops were taken at different voltages and the contact angles were calculated geometrically. Electrowetting on nanocone arrays was modeled using an energybased approach and the obtained theoretical curves were compared to the experimental ones. Oil helped in achieving a large contact angle change. A qualitative analysis of the electrowetting properties of the surfaces was done based on the voltage-contact angle curves.

The Scalable Parallel Random Number Generators library (SPRNG) is widely used due to its speed, quality, and scalability. Monte Carlo (MC) simulations often employ SPRNG to generate large quantities of random numbers. Thanks to fast Field-Programmable Gate Array (FPGA) technology development, this thesis presents Hardware Accelerated SPRNG (HASPRNG) for the Virtex-II Pro XC2VP30 FPGAs. HASPRNG includes the full set of SPRNG generators and provides programming interfaces which hide detailed internal behavior from users. HASPRNG produces identical results with SPRNG, and it is verified with over 1 million consecutive random numbers for each type of generator. The programming interface allows a developer to use HASPRNG the same way as SPRNG. HASPRNG introduces 4-70 times faster execution than the original SPRNG. This thesis describes the implementation of HASPRNG, the verification platform, the programming interface, and its performance.

This thesis investigates the reliability of ZigBee signal strength within a high-density wireless network, specifically looking at the Link Quality Indicator (LQI) as provided by the physical layer and accessible at the networking and application layers within the stack protocol. It also investigates methods by which LQI can be used for discovery, identification, and localization of nodes within a ZigBee wireless network. The thesis concentrates on practical approaches specifically as it would pertain to commissioning a high-density network for an application such as lighting control in building automation. There are seven potential algorithms proposed using factors such as minimum distance error, perceived confidence, and triangulation. Experiments, which explore the reliability of signal strength indicators, reveal that the fluctuations of the signal strength indicate that a simple, inexpensive algorithm is insufficient. Simulations, which explore varying conditions such as network layouts, node-count, and node-density, reinforce this notion; however, this thesis also shows that more complicated and expensive methods do show promising results. Using the simplest of methodologies, the experiments and simulations result in 30-35% accuracy. However, with the more complicated methodologies (using techniques such as reiteration, emulation, and cooperation), the results reveal accuracies of 80-90%. This thesis concludes from these results that a simple algorithm and methodology may not be sufficient but that there are approaches that can improve the results. However, the cost of these approaches may be deemed too high for practical use. Further exploration in these methodologies, though, should show promise that more sufficient accuracies without sacrificing too much cost are attainable.

The potential of micro-needles to provide an interconnection between the microscopic and the macroscopic worlds makes it one of the most revolutionary fields in health care, allowing for precise transdermal drug delivery of highly targeted small doses of the active compound. Current micro electro mechanical systems (MEMS) technologies, originally designed for the micro-electronics industry, have been utilized in the fabrication of different micro-needle designs and their integration with various micro-fabricated micro-fluidics devices. The target of this thesis is to achieve a micro-needle injection system to deliver several strains of pico-liter volumes of a fluid combination of transgenic virus and luminescent compound, to be injected into the visual cortex of mice in order to study the structure and function of the neural networks of the brain. Micro-needles having a body dimension of 10 mm x 10 mm and a shaft 1 mm wide and 3 mm long have been constructed from silicon wafers, using technologies originally developed for integrated circuit (IC) fabrication. Silicon wafers have also been used in the fabrication of the needle channels having a width of 4 μm and a total depth of 60 μm with a 20 μm deep channel at the base of the 40 μm trench. Both wet and dry bulk micromachining techniques have been used to create the needle bodies and channels. The optimum fabrication method has been found to be the deep reactive ion etching (DRIE) and SiO2 deposition using the plasma enhanced chemical vapor deposition (PECVD) has been used to seal the channels.

The advent of wireless sensor networks with emphasis on the information being routed, rather than routing information has redefined networking from that of conventional wireless networked systems. Demanding that need for contnt based routing techniques and development of low cost network modules, built to operate in large numbers in a networked fashion with limited resources and capabilities. The unique characteristics of wireless sensor networks have the applicability and effectiveness of conventional algorithms defined for wireless ad-hoc networks, leading to the design and development of protocols specific to wireless sensor network. Many network layer protocols have been proposed for wireless sensor networks, identifying and addressing factors influencing network layer design, this thesis defines a cross layer routing protocol (XLRP) for sensor networks. The submitted work is suggestive of a network layer design with knowledge of application layer information and efficient utilization of physical layer capabilities onboard the sensor modules. Network layer decisions are made based on the quantity of information (size of the data) that needs to be routed and accordingly transmitter power leels are switched as an energy efficient routing strategy. The proposed routing protocol switches radio states based on the received signal strength (RSSI) acquiring only relevant information and piggybacks information in data packets for reduced controlled information exchange. The proposed algorithm has been implemented in Network Simulator (NS2) and the effectiveness of the protocol has been proved in comparison with diffusion paradigm.

In fluorescence correlation spectroscopy and dynamic light scattering, digital correlators acquire the autocorrelation function of detected photons to measure diffusional dynamics of biomolecules and small particles. Multi-channel data from different wavelengths or scattering angles provide increased information for resolving multiple species. Similarly, in single-molecule spectroscopy and in experiments on photon entanglement, there is a need to acquire time stamps of photons from multiple detectors. To enable such advances, a cost-effective Multichannel Time-Correlator (MTC) and a Multichannel Hardware Simulator (MHS) were developed, each based on a reconfigurable digital input/output card, recently available from National Instruments. The field-programmable-gate-array (FPGA) cores of the cards are programmed to implement counters and first-infirst- out (FIFO) buffers for data transfer by direct-memory-access (DMA). The MTC scans 16 digital inputs each 12.5 nanoseconds to detect voltage pulses coming from a multichannel single-photon detector. Whenever one or more pulses are detected, the timing, which is recorded as a 32-bit timestamp, and a 16-bit flag that specifies the channel(s) are sent to the host computer (PC) for further analysis and storage to a binary file. The DMA data transfer to or from the host PC allows a sustained photon rate of >10 million per second among the 16 channels. An algorithm simultaneously calculates all 16x16 autocorrelation and cross-correlation functions for logarithmically spaced delays directly from the timestamps and channel flags. The MHS reads simulated timestamp and channel data from a binary file and sends the information by DMA to the FPGA card, which uses the received data to generate voltage pulses at 16 digital outputs to thereby simulate the signal from a 16-channel single-photon detector. When the MHS is connected to the MTC, each within a separate PC, the recovered timestamp data is correct to within the expected digital error of +/- 1 timing count.

This thesis examines the temperature effects on an ultracapacitor’s equivalent series resistance using a constant voltage source. Previous research has focused on developing models using constant current source. However, as the ultracapacitor technology develops, allowing for the expansion of these devices into new power applications, it is important to understand how ultracapacitors will perform in various temperatures and charging and discharging methods. By predicting the ultracapacitor behavior, systems can be optimized for efficiency and minimize internal circuit losses. For this thesis, Matlab was used to plot the experimental data and to provide best fit curves with their respective coefficients to allow for resistance measurements for one RC time constant to be performed. The research presented in this thesis shows the ultracapacitor’s series resistance was more dependent on change in current than temperature variations. The resistance was did show a minor dependence on temperature, however it was insignificant compared to the change in current levels. The analysis of the resistance values allowed for the development of a resistance equation that accounted for the variations in current and temperature. These resistive equations were compared to the calculated resistance measurements. Sufficient agreement was shown between the developed resistance equations and the calculated resistance values.

Medical care has been significantly improved in recent years due to tremendous technological advancement in the field of CMOS technology. Among those improvements, integrated circuit design and sensing techniques have brought to the doctors more flexibility and accuracy of examinations of their patients. For example, a diabetic patient needs to visit a hospital on a regular basis for the examination and proper treatment. However, with the tremendous advancement in electronic technology, a patient can soon monitor his or her own blood glucose level at home or at office with an implantable sensor which can also trigger insulin pump attached to the body. The insulin delivery system can be precisely controlled by the electronics embedded in the implantable device. In this thesis, a low power integrated circuit for the implantable biosensor incorporating an on-chip FSK modulator is presented. This design has been fabricated using AMI 0.5-μm CMOS process available through MOSIS. The simulation and test results are also presented to verify its operation.

AC electrokinetics (ACEK) is a promising technique to manipulate micro/bio-fluids and particles. It has many advantages over DC electrokinetics for its low applied voltage, portability and compatibility for integration into lab-on-a-chip devices. This thesis focuses on the design of a multi-functional orthogonal microelectrode system that induces ACEK effect for manipulation of microfluids and particles. Orthogonal electrode configuration used in this research can achieve maximum non-uniform electric field distribution, resulting in strong fluid and particle motion. In the experiments, three types of microflow fields were observed by changing the applied electric signals. Three ACEK processes, capacitive electrode polarization, Faradaic polarization, and AC electrothermal effect are proposed to explain the different flow patterns, respectively. Equivalent circuit model extracted from the impedance measurement helps to determine the optimal condition for ACEK implementation. Both numerical simulation and experimental results are presented and discussed in this thesis. Well controlled ACEK flow help transport target cells to the trapping site, which greatly enhanced the trapping efficiency by dielectrophoresis (DEP), thus long range particle manipulation can be achieved. Together with ACEK effect and pressure driven mechanism, a flow-through system based on orthogonal electrodes is created, which can be used to pump fluids and concentrate bio-particles so as to be able to handle solutions in large volume with low concentration. This simple and easily fabricated setup can be integrated as one component to form potential lab-on-a-chip devices.

A high voltage transformer connected to an atmospheric plasma generator is driven as a current-fed push-pull parallel resonant system, switched by a resonant lamp controller integrated circuit from Texas Instruments (UC3872) in such a manner as to be automatically maintained at resonance. The frequency range of interest is the audio range, which creates a particularly uniform glow discharge in atmospheric pressure air. Frequency control is achieved by a specially constructed high voltage variable capacitor connected parallel to the secondary, in conjunction with a variable parallel primary inductance. Voltage control is achieved by variation of the input DC current amplitude.