Thesis (M.S.) -- University of Texas at Dallas, 2006. / Includes vita. Includes bibliographical references (leaves 50-55)

Thesis (Ph. D.)--Ohio State University, 2006. / Title from first page of PDF file. Includes bibliographical references (p. 139-143).

We have investigated and implemented several general strategies in the development of microfluidics-based chemical/biochemical sensing systems. The research in this dissertation covers the immobilization of biological reagents inside microfluidic channels using polystyrene (PS) microbeads and photopolymerizable hydrogel, electrochemical sensing via electrochemiluminescence (ECL) reporting with bipolar and two-electrode configurations, and integration of these general functions to realize multiplexing and networking on-chip. Photopolymerizable hydrogel based on Poly(ethylene glycol) (PEG) and streptavidin-coated polystyrene (PS) microbeads were employed as building blocks as well as functional components in microfluidic system. PEG hydrogels can be used to define local microenvironments at different locations in the same microchannel, which enables the introduction of multiple sensing events on the same device. Monitoring of DNA hybridization and enzyme/substrate interaction were realized thereafter by using either fluorescence or electrochemistry as the detection method. Electrogenerated chemiluminescence based on Ru(bpy)32+ (bpy = 2,2??-bipyridine) and tripropylamine (TPA) was used to photonically report various redox events in microfluidic systems. By using microfluidic electrochemical cells based on either two-electrode or bipolar electrode (one-electrode), electroactive species that undergo reduction can be electrically linked to this anodic ECL process and thus be reported by the latter. This ECL sensing scheme essentially broadens the spectrum of redox compounds that can be detected by ECL since the analytes are not required to directly participate into the light-generating processes. Microfluidics offers some unique technical advantages of performing electrochemistry over conventional methods. In particular, laminar flow allows multiple analyte streams to be brought together in parallel with little mixing. Moreover, electrochemical signals can be generally utilized as a convenient means to link individual microchannels together hence to realize microfluidic networking and cross-communication. Electrochemical microfluidic devices can be used to mimic general functions of microelectronic devices such as diodes, transistors, and logic gates. These novel functions rendered by electrochemistry are believed to bring us closer to the final goals of micro total analysis systems and lab-on-a-chip.

Nano-sensors, as an application of nanotechnology, are extremely important for environmental, medical and security applications. Terahertz science is an exciting new field that is set to impact the field of sensing to a large extent. I proposed to combine the fields of nanotechnology and terahertz science and develop a molecular nano-sensor that operates at terahertz frequencies. I focused our sensing on energetic materials, particularly nitromethane, and conducted an extensive analysis on its frequency spectrum. The study also focused on designing the nano-sensor and determining its terahertz operation characteristics. I subjected it to various conditions through the use of molecular dynamics simulations. Finally we analyzed the simulation results and provided a proof of the concept that we had a working molecular nano-sensor that operates at terahertz frequencies and senses energetic materials. The results from the frequency analysis of nitromethane showed that the frequency characteristics determined from our simulations were in close agreement with the ones determined experimentally. In addition to this we also successfully demonstrated the use of a Lennard Jones potential to model the CN bond scission of nitromethane. Finally, the results from the interactions between the nano-sensor and nitromethane showed that the presence of nitromethane causes sufficient change in the terahertz frequency characteristics of the nano-sensor providing a means to detect nitromethane.

A wireless sensor network (WSN) is comprised of a few hundred or thousand au-tonomous sensor nodes spatially distributed over a particular region. Each sensornode is equipped with a wireless communication device, a small microprocessor, anda battery-powered energy source. Typically, the applications of WSNs such as habitatmonitoring, re detection, and military surveillance, require data collection, process-ing, and transmission among the sensor nodes. Due to their energy constraints andhostile environments, the main challenge in the research of WSN lies in prolongingthe lifetime of WSNs.In this dissertation, we present four dierent topology management protocols forK-coverage and load balancing to prolong the lifetime of WSNs.First, we present a Randomly Ordered Activation and Layering (ROAL) protocolfor K-coverage in a stationary WSN. The ROAL suggests a new model of layer cov-erage that can construct a K-covered WSN using the layer information received fromits previously activated nodes in the sensing distance. Second, we enhance the faulttolerance of layer coverage through a Circulation-ROAL (C-ROAL) protocol. Us-ing the layer number, the C-ROAL can activate each node in a round-robin fashionduring a predened period while conserving reconguration energy. Next, MobilityResilient Coverage Control (MRCC) is presented to assure K-coverage in the presence of mobility, in which a more practical and reliable model for K-coverage with nodalmobility is introduced. Finally, we present a Multiple-Connected Dominating Set(MCDS) protocol that can balance the network trac using an on-demand routingprotocol. The MCDS protocol constructs and manages multiple backbone networks,each of which is constructed with a connected dominating set (CDS) to ensure a con-nected backbone network. We describe each protocol, and compare the performanceof our protocols with Dynamic Source Routing (DSR) and/or existing K-coveragealgorithms through extensive simulations.The simulation results obtained by the ROAL protocol show that K-coverage canbe guaranteed with more than 95% coverage ratio, and signicantly extend networklifetime against a given WSN. We also observe that the C-ROAL protocol provides abetter reconguration method, which consumes only less than 1% of the recongura-tion energy in the ROAL protocol, with a greatly reduced packet latency. The MRCCprotocol, considering the mobility, achieves better coverage by 1.4% with 22% feweractive sensors than that of an existing coverage protocol for the mobility. The resultson the MCDS protocol show that the energy depletion ratio of nodes is decreasedconsequently, while the network throughput is improved by 35%.

In this study, ZnO film bulk acoustic resonators (FBARs) are proposed to fabricate the mass sensor of high sensitivity. The acoustic cavity is achieved by potassium hydroxide (KOH) etching. The FBAR structures are made of highly C-axis-oriented piezoelectric ZnO thin films using the technique of two-step deposition method. The titanium (Ti) seeding layer, platinum (Pt) bottom electrode, and aluminum (Al) top electrode were deposited by DC sputtering system using a dual gun. Finally, The remnants of silicon and silicon nitride (SiNx) are removed by reactive ion etching (RIE) etching. Furthermore, the two resonant frequencies of longitudinal mode and shear mode had been obtained. From the experimental results of loading effect with titanium and molybdenum, the mass sensitivity of the longitudinal mode and the shear mode are about 3200 Hz cm /ng and 1100 Hz cm /ng respectively, which are larger than those of quartz resonator or other reports. The measurement system was composed of a thermoelectric cooling module to investigate the temperature coefficient of frequency (TCF) of the mass sensor, which is about -70.67 ppm/. Bisides, the positive TCF material, silicon dioxode (SiO2) is deposited on ZnO thin films for the purpose of improving the TCF of FBAR devices. For SiO2/ZnO FBAR devices, the SiO2 reveal the compensation of TCF.

Automated devices enabled by wireless communications are deployed for a variety of purposes. As they become more ubiquitous, their interaction becomes increasingly important for coexistence when sharing a scarce resource, and for leveraging potential cooperation to achieve larger design goals. This thesis investigates the use of game theory as a tool for design and analysis of networked systems of automated devices in the areas of naval defence, wireless environmental monitoring through sensor networks, and cognitive radio wireless communications. In the first part, decentralized operation of naval platforms deploying electronic countermeasures against missile threats is studied. The problem is formulated as a stochastic game in which platforms independently plan and execute dynamic strategies to defeat threats in two situations: where coordination is impossible due to lack of communications, and where platforms hold different objectives but can coordinate, according to the military doctrine of Network Enabled Operations. The result is a flexible, robust model for missile deflection for advanced naval groups. Next, the problem of cooperative environmental monitoring and communication in energy-constrained wireless sensor networks is considered from a game-theoretic perspective. This leads to novel protocols in which sensors cooperatively trade off performance with energy consumption with low communication and complexity overhead. Two key results are an on-line adaptive learning algorithm for tracking the correlated equilibrium set of a slowly varying sensor deployment game, and an analysis of the equilibrium properties of threshold policies in a game with noisy, correlated measurements. Finally, the problem of dynamic spectrum access for systems of cognitive radios is considered. A game theoretic formulation leads to a scheme for competitive bandwidth allocation which respects radios' individual interests while enforcing fairness between users. An on-line adaptive learning scheme is again proposed for negotiating fair, equilibrium resource allocations, while dynamically adjusting to changing conditions.

This work explores some of the considerations for the design and operation of a fungal spore sensor using Magnetic Resonance Force Microscopy (MRFM). This work starts by introducing the physics, components and theory of operation which make MRFM a favourable method for detecting the presence of fungal spores, which have physical dimensions in the range of a few microns to a few hundred microns. MATLAB was used to simulate changes in the dipole magnetic force which acts between a mold spore and a MEMS cantilever beam during a MRFM experiment. The dimensions, characteristics and response of the cantilever beam is estimated using MATLAB and re ned with multiple simulations in COMSOL Multiphysics. The results are two cantilever models, one made using silicon and the other silicon nitride, have approximate quality factors of 30, spring constants around 80 10^6 N/m and resonance frequencies close to 10 kHz. This work also discusses the proposed manufacturing process and considerations for the MEMS cantilever structure and the additional components of the intended prototype sensor. A sequence of operation for the initial calibration and typical operation of the spore sensor is also included in this work. The fungal spore itself is adhered within the sensing range of the sensor by using an antibody selectively chosen to bind with the targeted spore. This work concentrates on the detection of the Botryris cinerea fungal spore, however the results from this work can be easily expanded on to detect additional fungal spores by changing the monoclonal antibody used to target the other spore types

The importance of monitoring physical and environmental conditions increases day by day and, therefore, so is the necessity of having a reliable wireless sensor network (WSN). The need to overcome challenges in WSN deployment and operation arises due to WSN's nature and characteristics such as possible nodes' mobility, limited radio and processing power, available storage and physical effects of the environment (particularly harsh environments) and balancing energy consumption has motivated us to investigate solutions to those problems. By studying related work, it was possible to observe that techniques such as the use of a good link estimator and the deployment of a suitable topology are essential features for a WSN. The core idea is to capture link connectivity dynamically and use it on routing decisions to gain reliability and estimate the whole network connectivity. The three main steps for deployment of a reliable WSN are the following: -         Link estimator -         Routing and neighbor information -         Suitable routing algorithms In addition, self-organization is an important capability that WSNs need to present. They should be reliable, scalable and energy efficient during the network lifetime and self-organization plays a key role in this context. Summing up all these aspects, it comes to the point that reliable connectivity is an important characteristic of a WSN. The goal of this work is to contribute with the research in the subject by means of implementing a suitable topology management and evaluating the network connectivity by the means of quantitative metric for the network as whole. Practical experiments results are presented and discussed.

This is a master thesis of the Master of Science degree program in Applied Physics and Electrical Engineering at Linköping University. The goal of this thesis is to find out how the Microsoft Kinect can be used as a part of a camera rig to create accurate 3D-models of an indoor environment. The Microsoft Kinect is marketed as a touch free game controller for the Microsoft Xbox 360 game console. The Kinect contains a color and a depth camera. The depth camera works by constantly projecting a near infrared dot pattern that is observed with a near infrared camera. In this thesis it is described how to model the near infrared projector pattern to enable external near infrared cameras to be used to improve the measurement precision. The depth data that the Kinect output have been studied to determine what types of errors it contains. The finding was that the Kinect uses an online calibration algorithm that changes the depth data.