published_or_final_version / Physiology / Doctoral / Doctor of Philosophy

This thesis describes novel microel ectromechanical system (MEMS) based electrochemical gas sensors and methods of fabrication. This thesis presents the research in two parts. In the first part, a method to handle a thin silicon wafer using an electrochemically active adhesive is described. Handling of a thin silicon wafer is an important issue in 3D-IC manufacturing where through silicon vias (TSVs) is an enabling technology. Thin silicon wafers are flexible and fragile, therefore difficult to handle. In addressing the need for a reliable solution, a method based on an electrochemically active adhesive was developed. In this method, an electrochemically active adhesive was diluted and spin coated on a 100 mm diameter silicon wafer (carrier wafer) on which another silicon wafer (device wafer) was bonded. Device wafer was subjected to post processing fabrication technique such as wafer thinning. Successful debonding of the device wafer was achieved by applying a voltage between the two wafers. In another part of the research, a fabrication process for developing a functional nanoporous material using atomic layer deposition is presented. In order to realize a nanoporous electrode, a nanoporous anodized aluminum oxide (AAO) substrate was used, which was functionalized with very thin layers (~ 10 nm) of platinum (Pt) and aluminum oxide (Al2O3) using atomic layer deposition. Nanoporous material when used as an electrode delivers high sensitivity due to the inherent high surface area and is potentially applicable in fuel cells and in electrochemical sensing. The second part of the thesis addresses the need for a high performance gas sensor that is applicable for asthma monitoring. Asthma is a disease related to the inflammation in the airways of the lungs and is characterized by the presence of nitric oxide gas in the exhaled breath. The gas concentration of above approximately 50 parts-per-billion indicates a likely presence of asthma. A MEMS based electrochemical gas sensor was successfully designed and developed to meet the stringent requirements needed for asthma detection. Furthermore, to enable a hand held asthma measuring instrument, a miniaturized sensor with integrated electrodes and liquid electrolyte was developed. The electrodes were assembled at a wafer-level to demonstrate the feasibility towards a high volume fabrication of the gas sensors. In addition, the designed amperometric gas sensor was successfully tested for hydrogen sulphide concentration, which is a bio marker for bad breath. / <p>QC 20150907</p>

Male-typical copulatory behaviors such as mounting and intromission are dependent on testicular androgens in most vertebrates, being eliminated by castration and re-instated by administration of exogenous testosterone. Testosterone implants in the preoptic area (POA) can re-instate behavior as effectively as systemic testosterone replacement, implicating this area as a critical locus of hormonal gating. The cellular mechanisms underlying this gating phenomenon are not well understood, but according to one model, testosterone induces an up-regulation of nitric oxide synthase (NOS) in the POA, increasing nitric oxide synthesis following exposure to a sexual stimulus. Nitric oxide in turn, possibly through its effect on catecholamine turnover, influences the way the stimulus is processed and enables the appropriate copulatory behavioral response. The experiments described in this Dissertation were designed to test this model as it pertains to hormonal gating in Cnemidophorus lizards. Specifically, experiments were conducted to test the predictions that nitric oxide synthesis inhibition would suppress the expression of behavior; that preoptic nitric oxide synthesis would be greater in animals expressing copulatory behavior; and that preoptic NOS expression, at both the mRNA and the protein levels, would be greater in animals exposed to testosterone than in animals deprived of hormone. All three of these predictions were upheld, offering support to the model as described. / text

published_or_final_version / Medical Sciences / Master / Master of Medical Sciences

published_or_final_version / Medical Sciences / Master / Master of Medical Sciences

published_or_final_version / Physics / Master / Master of Philosophy

published_or_final_version / Medicine / Master / Master of Philosophy

published_or_final_version / Electrical and Electronic Engineering / Doctoral / Doctor of Philosophy

No description available.

No description available.