Trapping ability on a biochip device is useful for systematic cell addressing and real-time observation of single cells analysis, however, precise control over the cell movements remains challenging. This thesis addresses the problem of controlling movement of single cells on a biochip platform by a technique called the Dielectrophoretic (DEP) force. Existing researches showed that the DEP force offers precise control of cell movements through various microelectrode designs which generate strong polarization effects i.e., DEP forces, but with the expense of damaging cell’s structure. The thesis contribute three new microelectrode designs for trapping single cells: the dipole, the quadrupole and the adaptive octupole, structured on a metal-insulator-metal (multilayer) biochip platform called the Sandwiched Insulator with Back Contact (SIBC) biochip. Cores of the study lie on the microelectrode designs that are capable of generating strong DEP holding forces, the back contact to enhance trapping of single cells and the fabrication process of creating a metal-insulator-metal structure. This thesis also presents details on the experimental setups of the trapping experiments and the numerical analysis of the microelectrode designs. The SIBC biochip comprises of the back contact on the first metal layer, the microcavity (cell trap) on the insulator layer and the three microelectrodes on the second metal layer. Together, the three microelectrodes and the back contact generate DEP forces that attract particles/single cells toward microcavities and maintain their positioning in the traps. Prior to the fabrication, profiles of the DEP force generated by the microelectrodes are studied using COMSOL3.5a software. Simulation results suggest that the DEP trapping region can be created surrounding the microcavity if the microelectrode and the back contact are connected with AC signals that have different phases. The strongest DEP force can be obtained by setting the back contact and the microelectrodes with AC signals that have 180 degree phase difference. Evaluations on the trapping functionality for the three microelectrodes were conducted using polystyrene microbeads and Ishikawa cancer cells line suspended in various medium. Trapping capability of the three microelectrodes was demonstrated through experiments with 22 percent of the Ishikawa cancer cells and 17 percent of the polystyrene microbeads were successfully trapped. With these promising results, the new microelectrode designs together with the SIBC biochip structure have huge potentials for biomedical applications particularly in the field of diagnosis and identification of diseases.

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No description available.

Cavity flow-acoustic resonances may occur when a fluid stream flows past a recessed cavity in a wall. These resonances may lead to high unsteady pressure levels. The resonance involves a coupling between the instability wave which propagates downstream on the shear-layer that spans the open face of the cavity, and acoustic waves that propagate back upstream inside and outside the cavity. These waves are coupled by the scattering processes at the ends of the cavity. Previous theoretical research considered cavities in a wall that bounds an infinite stream. In many of the experiments on cavity resonances, however, the cavity is placed in a side wall of a wind tunnel. When the surrounding wind tunnel walls are not acoustically treated, the resonances can be very strong. My research is a theoretical investigation of the case of a cavity in a side wall of a wind tunnel. Recently, a mode trapping phenomenon has been proposed as an explanation for the very strong cavity resonances in the wind tunnel case. The mode trapping occurs when the critical frequency of a mode in the tunnel-cavity region is slightly lower than the critical frequency of the corresponding mode in the tunnel region. The region between these two critical frequencies is defined as a frequency window. Experiments show that very high pressure levels are observed in these frequency windows. The goal of my research is to develop a global theory of cavity resonances in the wind tunnel geometry. The global theory couples solutions for the instability wave and the acoustic waves through scattering analyses at the ends of the cavity. Resonance frequencies, spatial mode shapes and linear growth rates are predicted. The theoretical predictions are consistent with experimental measurements and demonstrate that the mode trapping phenomenon explains the experimentally observed behavior.

Para atingir o regime de condensação de Bose-Einstein (CBE) em gases de metais alcalinos são necessárias várias etapas: feixe desacelerado, aprisionamento magneto-óptico, aprisionamento magnético e por fim o resfriamento evaporativo. Como estamos interessados em atingir o regime de CBE precisamos nos preocupar com as várias etapas intermediárias. Neste trabalho apresentaremos a construção e caracterização de uma armadilha magnética para um gás de átomos neutros de sódio. O sistema optado por nós foi o \"folha de trevo\", com o qual conseguimos a seguinte configuração de campos magnéticos: 140 gauss de campo de fundo na direção axial, 117 gauss/cm de gradiente radial e 106 gauss/cm 2 de curvatura na direção axial. Para gerarmos esta configuração de campo e desligarmos estes campos em um tempo menor que um milisegundo foi necessária a construção de um sistema de chaveamento e controle que será descrito e caracterizado neste trabalho. Com este sistema em funcionamento observamos aproximadamente 10 8 átomos aprisionados e um tempo de 1 segundo. Além disso, observamos os átomos adaptando-se a diferentes formas de potenciais de aprisionamento / In order to obtain Bose- Einstein condensation ( BEC ) in alkali gases several steps are needed : slowing beam , magneto- optical trapping , trapping magnetic and finally evaporative cooling . Since, we are interested in achieving BEC regime we need to consider about the various intermediate steps . In this work, we present the construction and characterization of a magnetic trap for a gas neutral atom of sodium. The system we chose was the \" clover leaf \" , with which we got the following configuration of magnetic fields : 140 gauss field background in the axial direction , 117 gauss / cm radial gradient and 106 gauss / cm 2 of curvature axial direction . For generating this field configuration and disconnecting these fields in a time of less than one millisecond required the construction of a switching system and control that will be described and characterized in this work. With this system, noted in about 10 8 trapped atoms and a time of 1 second. Besides, we observe the atoms adapting to different forms of potential imprisonment

Non-contact manipulation technologies present a useful and powerful means of handling particles or cells. Such techniques are of interest in regenerative medicine applications, and in particular the scalability of these techniques is an area of active research. Optical trapping is a precise and dextrous method of manipulating particles with the forces exerted by a laser beam, while acoustic trapping is a scalable technique capable of exerting a force on particles through standing wave resonance. These complimentary modalities can be utilised in a hybrid system to give a resultant technique that borrows from the strengths of each individual method. In this thesis, methods of force balancing, using optics and acoustics, are explored, both independently and in combination with each other. A technique for 3D acoustic trapping in glass capillaries is shown, utilising the two pairs of opposing channel walls and the air-water interfaces of two air bubbles as acoustic reflectors. Standing waves set up between these surfaces show discrete acoustic trapping sites for varying lengths of fluid cavity. A method of optical radiation force balancing is observed in a 3D potential energy landscape, using similar principles as seen in particle trapping with counter-propagating beams. Tuning of the radiation force balance in this system allows particles to, instead of being pinned to the surface by the radiation force from the optical pattern, become localised at discrete planes of trapping sites throughout the fluid volume. A hybrid force balance separation method using the optical and acoustic forces is devised using a single laser beam as the primary deflection mechanism with acoustic trapping providing both localisation and a force balance with the optics. Separation of different sized particles is observed, with larger scale optical deflection mechanisms and their resultant thermal effects demonstrated.

The Kizler North Field is near the western flank of the Forest City Basin in Lyon Co., Kansas, USA and produces oil from the Hunton Formation, Viola Formation and Simpson Group reservoirs. The structure strikes NW through the field that is part of a larger wrench fault system. This modern prospect analysis of the Kizler North Field, aids in understanding the reservoir properties of the Hunton Formation, Viola Formation and Simpson Group rocks, the play mechanism of the field, and provides recommendations for additional drilling locations.

In broad terms, this thesis is concerned with the measurement and interpretation of carrier lifetimes in multicrystalline silicon. An understanding of these lifetimes in turn leads to a clearer picture of the limiting mechanisms in solar cells made with this promising material, and points to possible paths for improvement. The work falls into three broad categories: gettering, trapping and recombination. A further section discusses a powerful new technique for characterising impurities in semiconductors in general, and provides an example of its application. Gettering of recombination centres in multicrystalline silicon wafers improves the bulk lifetime, often considerably. Although not employed deliberately in most commercial cell processes, gettering nevertheless occurs to some extent during emitter formation, and so may have an important impact on cell performance. However, the response of different wafers to gettering is quite variable, and in some cases is non-existent. Work in this thesis shows that the response to gettering is best when the dislocation density is low and the density of mobile impurities is high. For Eurosolare material these conditions prevail at the bottom and to a lesser extent in the middle of an ingot. However, these conclusions can not always be applied to multicrystalline silicon produced by other manufacturers. Low resistivity multicrystalline silicon suffers from a concurrent thermally induced degradation of the lifetime. This had previously been attributed to the dissolution of precipitated metals, although we note that the crystallographic quality also appears to deteriorate. The thermal degradation effect results in an optimum gettering time for low resistivity material. Edge-defined Film-fed Growth (EFG) ribbon silicon was also found to respond to gettering, and even more so to bulk hydrogenation. Evidence for Cu contamination in the as-grown EFG wafers is presented. Multicrystalline silicon is often plagued by trapping effects, which can make lifetime measurement in the injection-level range of interest very difficult, and sometimes impossible. An old model based on centres that trap and release minority carriers, but do not interact with majority carriers, was found to provide a good explanation for these effects. These trapping states were linked with the presence of dislocations and also with boron-impurity complexes. Their annealing behaviour and lack of impact on device parameters can be explained in terms of the models developed. The trapping model allowed a recently proposed method for correcting trap-affected data to be tested using typical values of the trapping parameters. The correction method was found to extend the range of useable data to approximately an order of magnitude lower in terms of carrier density than would be available otherwise, an improvement that could prove useful in many practical cases. High efficiency PERL and PERC cells made on gettered multicrystalline silicon resulted in devices with open circuit voltages in the 640mV range that were almost entirely limited by bulk recombination. Furthermore, the injection-level dependence of the bulk lifetime resulted in decreased fill factors. Modelling showed that these effects are even more pronounced for cells dominated by interstitial iron recombination centres. Analysis of a commercial multicrystalline cell fabrication process revealed that recombination in the emitter created the most stringent limit on the open circuit voltage, followed by the bulk and the rear surface. The fill factors of these commercial cells were mostly affected by series resistance, although some reduction due to injection-level dependent lifetimes seems likely also. Secondary Ion Mass Spectroscopy on gettered layers of multicrystalline silicon revealed the presence of Cr and Fe in considerable quantities. Further evidence strongly implied that they resided almost exclusively as precipitates. More generally, injection-level dependent lifetime measurements offer the prospect of powerful contamination-monitoring tools, provided that the impurities are well characterised in terms of their energy levels and capture cross-sections. Conversely, lifetime measurements can assist with this process of characterising impurities, since they are extremely sensitive to their presence. This possibility is explored in this thesis, and a new technique, dubbed Injection-level Dependent Lifetime Spectroscopy (IDLS) is developed. To test its potential, the method was applied to the well-known case of FeB pairs in boron-doped silicon. The results indicate that the technique can offer much greater accuracy than more conventional DLTS methods, and may find applications in microelectronics as well as photovoltaics.

Isoelectric trapping (IET) in multicompartment electrolyzers (MCE) has been widely used for the electrophoretic separation of ampholytic compounds such as proteins. In IET, the separation occurs in the buffering membranes that form a step-wise pH gradient in the MCE. Typically, buffering membranes have been made by copolymerizing acrylamide with Immobiline compounds, which are acidic and basic acylamido buffers. One major problem, however, is that these buffering membranes are not stable when exposed to high concentrations of acid and base due to hydrolysis of the amide bonds. Poly(vinyl alcohol)-based, or PVA-based, membranes were made as an alternative to the polyacrylamide-based membranes since they provide more hydrolytic and mechanical stability. Four mid-pH, PVA-based buffering membranes that contain single ampholytes were synthesized. These buffering membranes were used to trap small molecular weight pI markers for up to three hours, and were also used in desalting experiments to remove strong electrolytes from a solution of ampholytes. Additionally, the membranes were used in IET experiments to separate mixtures of pI markers, and to fractionate the major proteins in chicken egg white. The membranes did not show any degradation when stored in 3 M NaOH for up to 6 months and were shown to tolerate current densities as high as 16 mA/cm2. In addition, six series of PVA-based membranes, whose pH values can be tuned over the 3 < pH < 10 range, were synthesized by covalently binding aminodicarboxylic acids, and monoamines or diamines to the PVA matrix. These tunable buffering membranes were used in trapping experiments to trap ampholytes for up to three hours, and in desalting experiments to remove strong electrolytes from a solution of ampholytes. These tunable buffering membranes were also used in IET experiments to separate proteins, some with pI values that differ by only 0.1 pH unit. The tunable buffering membranes did not show any signs of degradation when exposed to 3 M NaOH for up to 3 months, and could be used in IET experiments with current densities as high as 20 mA/cm2. These tunable buffering membranes are expected to broaden the application areas of isoelectric trapping separations.

Biologists often trap animals to obtain information on them. If trapping is selective toward some animals, the information may be inaccurate. Most mammalogists know or suspect that their trapping techniques (reviewed by Hayne, 1949; and Stickel, 1954) contain sources of bias. Since trapping remains the only feasible way to obtain information on many animals, researchers have tried to discover sources of sampling error and refine their techniques. They have found that one major source of difficulty may lie in the behavior of animals. Individual animals seem to respond differently to trapping, both initially and through learning (Geis, 1955; Crowcroft and Jeffers, 1961; and others). However, researchers seldom observe the behavioral responses of animals to traps. They infer information from capture data. Perhaps an empirical approach would shed more light on the relationship between behavior and trapping. The present study is such an approach. The study concerns the behavioral responses of adult Uinta ground squirrels, Citellus armatus, to trapping. I based the study on the direct observations of known individuals in a wild population. My primary objective was to learn how animals respond to a trap, to capture, and to recapture. My approach was both that of a population ecologist interested in factors affecting trapping success and that of a behaviorist interested in the effect of trapping procedures on the behavior of animals. I conducted a broad ecological and behavioral study of the population (Balph and Stokes, 1963) before beginning the research on trap response, which helped me select parameters and develop procedures. I also conducted a pilot study on deer mice, Peromyscus maniculatus, in the laboratory to test some procedures and the design of the trap-response investigation.