Zugl.: Aachen, Techn. Hochsch., Diss., 2007.

Regensburg, Univ., Diss., 2008

Zugl.: München, Techn. Univ., Diss., 2008

Includes bibliographical references (p. 115-121).

Chemnitz, Techn. Univ., Diplomarb., 2007.

Universiẗat, Diss., 2000--Tübingen.

abstract: This work demonstrates the integration of a wearable particulate detector and a wireless chemical sensor into a single portable system. The detection philosophy of the chemical sensor is based on highly selective and sensitive microfabricated quartz tuning fork arrays and the particle detector detects the particulate level in real-time using a nephelometric (light scattering) approach. The device integration is realized by carefully evaluating the needs of flow rate, power and data collection. Validation test has been carried out in both laboratory and in field trials such as parking structures and highway exits with high and low traffic emissions. The integrated single portable detection system is capable of reducing the burden for a child to carry multiple devices, simplifying the task of researchers to synchronize and analyze data from different sensors, and minimizing the overall weight, size, and cost of the sensor. It also has a cell phone for data analysis, storage, and transmission as a user-friendly interface. As the chemical and particulate levels present important exposure risks that are of high interests to epidemiologists, the integrated device will provide an easier, wearable and cost effective way to monitor it. / Dissertation/Thesis / M.S. Electrical Engineering 2012

O objeto de estudo deste trabalho é caracterizar um transdutor magnético de posição absoluto de longo percurso e robusto quanto à sua resposta dinâmica. O transdutor foi concebido na dissertação de mestrado do autor e denominada de ¨Régua Magnética¨na qual foi estudada a sua resposta estática. Diferentemente de outros transdutores magnéticos este tem como princípio de funcionamento a divisão do fluxo magnético entre dois caminhos distintos, cujas dimensões variam em função da movimentação da bobinas de excitação. Neste estudo analisa-se então a resposta dinâmica do transdutor, pois, quando o seu carro se desloca com velocidade constante, há uma modificação na grandeza física que é responsável pelo sinal de saída correlacionado à posição daquele carro. O estudo foi desenvolvido em dois transdutores de aproximadamente 2 m de comprimento confeccionados com lâminas de Fe-Si cortadas a laser. Os sinais de tensão induzida nas culatras, corrente e fluxo magnético no eletro-ímã do carro bem como o sinal de posição deste são coletados por um dispositivo digital e processados em um computador de modo a se poder obter as curvas estáticas e dinâmicas e assim compará-las. Com este propósito, foi desenvolvida uma bancada original de ensaio de transdutores de posição lineares para a medição da diferença dos sinais entre o caso estático e o dinâmico, denominado de diferença dinâmica, na qual foi empregado um transdutor de posição resistivo para a referência de posição, um sistema de aquisição de sinais para a medição das grandezas envolvidas no processo e um conjunto movimentador e servomotor para controle da velocidade e posição da parte móvel do transdutor. No final deste trabalho são comparados os resultados analíticos e experimentais obtidos como antes descritos. / The aim of this work is to characterize a long-span absolute magnetic position transducer that presents a robust dynamic response. The transducer was conceived by the MSc studies of the author and is called named “Magnetic Ruler” by which its static response was studied. Unlike other magnetic transducers, the magnetic ruler is based on the principle of the division of magnetic flux between two distinct magnetic paths that depends on the linear position of its movable part along the span of the transducer. This present study examines the dynamic response of the transducer when its movable part or car is moving with constant speed. Under such conditions, there is a change in the signal output that is correlated to the position of that car. The study was conducted by means of two transducers of approximately 2-m long laminations of Si-Fe that were laser cut. The voltage signals induced through the search coils on the end yokes, current and magnetic flux in the excitation coil on car, and the position are acquired by a digital device and processed by a computer. That is done to obtain the static and the dynamic curves and, thus, to allow the comparison between the two behaviors. With this objective, a specially built and unique test bench was developed to test linear position transducers under static and dynamic cases. The difference between the two results is called dynamic difference. That test bench employs a resistive position transducer to provide position reference, a signal acquisition system for measuring the quantities involved in the process, and a controlled traction system based on a servo system to control the speed and the position of the moving part of the transducer under test. At the end this work the analytical and experimental results obtained as described above are compared.

In the first study, a new µ-HPLC column was developed using a monolithic silica gel as a column substrate for chiral separation by covalently modifying with (S, S)-Whelk-O1 chiral selector. The monolithic stationary phase was generated through a sol-gel process and prepared in situ in a 100 µm i.d. fused silica capillary tubing. The chromatographic performance was characterized in terms of retention factor, column efficiency, enantioselectivity and resolution, as well as the kinetics parameters affecting the separation. Comparison with a commercial particle packed HPLC column demonstrates a promising enantioselective resolving ability of the monolithic Whelk-O1 capillary column. The second project focuses on characterization of fluorescent sensor for zinc detection. In this work, we have examined the photophysical properties of the fluorescent probe sensor that has been developed in our laboratory for Zn2+ recognition via a photo-induced electron transfer (PET) sensing mechanism. To characterize the fundamental function of sensor, response curves have been conducted, using acetone/methanol (199:1), 1,4-dioxane, acetone, methanol and aqueous buffer as the solvent system. Similar to prior work from our group, the sensor was found to respond selectively to Zn2+ ions with fluorescence enhancement. The fluorescence properties and binding response were evaluated in the presence of water and a Lewis base, which we found to have a marked effect on the fluorescence signal. The selectivity of the sensor for Zn2+ was also observed and compared to other divalent metal such as Ca2+, Mg2+, Cu2+ and Hg2+ with the goal of learning fundamental information on the system that can aid in the development of future PET based sensors.

Submitted by Ranilson Angelo da Silva null (ranilsonangelo@yahoo.com.br) on 2016-10-03T13:42:06Z No. of bitstreams: 1 Tese Doutorado_Ranilson_Final.pdf: 16582757 bytes, checksum: de5b3924045b0020ea737e76aa06ee18 (MD5) / Approved for entry into archive by Ana Paula Grisoto (grisotoana@reitoria.unesp.br) on 2016-10-05T19:07:16Z (GMT) No. of bitstreams: 1 silva_ra_dr_araiq.pdf: 16582757 bytes, checksum: de5b3924045b0020ea737e76aa06ee18 (MD5) / Made available in DSpace on 2016-10-05T19:07:16Z (GMT). No. of bitstreams: 1 silva_ra_dr_araiq.pdf: 16582757 bytes, checksum: de5b3924045b0020ea737e76aa06ee18 (MD5) Previous issue date: 2016-06-29 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / A eficiência dos materiais semicondutores óxidos metálicos utilizados em dispositivos sensores, depende fortemente de parâmetros morfológicos e estruturais. É de grande interesse que os materiais apresentem um elevado grau nos parâmetros de medidas que definem um bom sensor, como: sinal, sensibilidade, seletividade. Devido a isso, métodos de sínteses adequados têm grande influência no desempenho dos dispositivos, já que interferem diretamente na morfologia e estrutura dos materiais semicondutores. Através dessa perspectiva, nesse trabalho, morfologias do composto semicondutor óxido metálico ZnO foram superficialmente modificadas com o intuito de realizar melhorias para aplicações em sensores de gás e de radiação luminosa (fotocondução) na faixa do ultravioleta. Dois métodos de sínteses foram utilizados: i) evaporação térmica por redução carbotérmica e ii) hidrotermal assistido por micro-ondas, responsáveis por obter morfologias tipo tetrapés e estrelas multipontas, respectivamente. Processos de evaporação térmica por redução carbotérmica tem a grande vantagem de obter estruturas com morfologias unidimensionais, em contrapartida, o método hidrotermal assistido por micro-ondas pode sintetizar uma enorme gama de diferentes morfologias com a vantagem de ser um processo rápido e de baixos custos energéticos. Técnicas como microscopia eletrônica de varredura, microscopia eletrônica de transmissão, difração de raios-X, espectroscopia ultravioleta visível e infravermelho, foram utilizadas para caracterizar o material em seu aspecto morfológico e estrutural. Análises em gases como NO2, CO e H2, e da radiação eletromagnética na região ultravioleta, foram realizadas com a finalidade de se obter parâmetros relevantes como, sinal do sensor (para aplicação em sensor de gás) e responsividade (para aplicação em fotocondução), e verificar a performance do ZnO puro e decorado nesses dois seguimentos de aplicação. Através dos resultados e possível observar que houve boa uniformidade das partículas metálicas aderidas à superfície do ZnO. Com relação as respostas do sensor de gás para os materiais puros e decorados houve um aumento do sinal para decoração com Ag na presença do gás H2. Na presença do gás NO2 o material puro obteve um maior sinal, para ambas morfologias. Já para o gás CO, somente é observado uma resposta do sensor para as estrelas multipontas decoradas com platina. A responsividade das amostras de tetrapés foram elevadas em comparação as amostras de estrelas multipontas com valor da ordem de 0,8 A/W. Os resultados obtidos são de fundamental importância para contribuição científica e levanta margem para um foco ainda mais profundo para o desenvolvimento de dispositivos sensores de alto desempenho. / Efficiency of the metal oxide semiconductor materials used in sensor devices, relies heavily on morphological and structural parameters. Is of great interest that the materials have a high degree in the measurement parameters that define a good sensor, such as signal sensitivity, selectivity. Methods suitable synthesis have great influence on the performance of the devices, since they directly affect the morphology and structure of the semiconductor materials. Therefore, in this work, morphologies of the compound semiconductor metal oxide ZnO were surface modified in order to make improvements for applications in gas sensors and light radiation (photoconduction) in the ultraviolet range. Two methods of synthesis were used: i) thermal evaporation by carbothermal reduction and ii) hydrothermal assisted by microwave, responsible for obtaining morphologies type tetrapods and stars multi-point, respectively. Thermal evaporation processes by reduction carbothermic, has the great advantage of obtaining structures with one-dimensional morphology, however, the hydrothermal method assisted by microwave can synthesize a wide range of different morphologies with the advantage of being a quick process and lower costs energy. Techniques such as scanning electron microscopy, transmission electron microscopy, X-ray diffraction, ultraviolet–visible spectroscopy and infrared, were used to characterize the material in its morphological and structural aspect. Analysis of gases such as NO2, CO and H2, and electromagnetic radiation in the ultraviolet region were performed in order to obtain relevant parameters as sensor signal (for use in gas sensor) and responsivity (for use in photoconduction) and check the performance of ZnO and decorated ZnO, in these two application segments. From the results it is observed that there was good uniformity of metal particles adhered to the surface of ZnO. In relation the responses of the gas sensor for pure and decorated material, there was an increase signal for decoration with Ag in the presence of H2 gas. In the presence of NO2 gas, there was a higher signal to both morphologies of pure ZnO. For CO gas, a response to the multi-point stars decorated with platinum is observed. The responsivity of the tripods samples was high compared with multi-point stars, with value of the order of 0.8 A / W. The results are of fundamental importance for scientific contribution and raises margin for an even deeper focus to developing high-performance sensor devices.