Hydrogen ion-sensitive field effect transistor with sol-gel-derived La-modified lead titanate gate Department of Electrical Engineering, National Sun Yat-Sen University *Jen-Fu Su **Ying-Chung Chen Abstract In this thesis the amorphous lead lanthanum titanate (Pb1-xLaxTi1-x/4O3, PLT) membrane has been prepared by sol-gel method as a novel pH-sensitive layer. The lead lanthanum titanate membrane was directly deposited on the SiO2(1000Å)/p-Si substrate by spin-on coating to form the PLT/SiO2/Si EIS structure. The C-V measurement was used for examining the fabrication parameters and sensing properties. Moreover, the PLT membrane was grown onto the SiO2 gate ISFET as the PLT/SiO2 gate ISFET. The electrical properties with the different parameter conditions can be obtained by the I-V measurement. Experimental results show that the fabrication parameters and characteristics of the PLT membrane are determined at the La-modified content about 3 mol% and the firing temperature of 400¢J via the EIS structure. There exhibits the pH response of about 44-52 mV/pH in the range of pH 2-12. Furthermore, the nonideal factors, such as drift of 0.1-0.3 mV/h, hysteresis of 2-13 mV and lifetime decay of about 72 mV/pH-day, can be also obtained via the I-V properties of the ISFET. Finally, the hardware architecture of pH measuring system has been built up. The system makes use of constant current and voltage bias technique to ensure that the variations of the output voltage can give directly the variations of pH value. For the purpose of achieving the function of data calibration and driving the liquid crystal display (LCD), the 8051 microprocessor is employed. Keywords: ISFET, Sol-gel, Lead lanthanum titanate, Drift, Hysteresis, pH meter * Student ** Advisor

[pt] Os medidores de pH existentes no mercado indicam valores confiáveis, dentro de uma incerteza declarada para cada modelo fabricado. Entretanto, normalmente, não é citada a especificação em termos do tempo necessário para alcançar estes valores, devido ao tempo de resposta do instrumento. Esta dissertação de mestrado tem como objetivo desenvolver uma metodologia teórico-experimental para avaliar o desempenho do transdutor em condições transientes, indicando alguns valores típicos para medidores comerciais, e sua resposta na medição de pH, a partir do modelo testado em uma reação experimental, sendo o mesmo simulado em outras reações químicas para diferentes velocidades de reação.Através deste modelo qualificado, foram avaliados os erros devidos às respostas permanentes e transientes, mostrando em que condições o medidor de pH pode ser usado, a partir da comparação entre valores de pH real e valores de pH registrados pelo medidor, levando em consideração a temperatura e o tempo de reação. / [en] The electrochemical analysers available in the market assert trustworthy values applicable in a specific uncertainty range, which varies depending on the unit`s model.Nevertheless, rarely is given any information on the time necessary to reach these values, which depend on the answer of the instrument. This Master`s dissertation aims to develop an experimental theoretical methodology to evaluate the performance of the transducer in transient conditions, and obtain some typical values for commercial analysers, and its answer in the pH measurements in simulated chemical reactions in various reaction velocities. Through the qualified model, the errors due to the permanent and transient answers were evaluated, establishing the conditions pH electronic units can be used, in a pre-set controlled error, from the comparison between real pH values and displayed pH values in the analysers, considering the temperature and the reaction time.

This research advances the current understanding of the carbonation reaction in porous materials by investigating pH changes during the hardening process of lime, the role of pore-water in the dissolution process of calcium hydroxide and the effects of pore size on precipitation of calcium carbonate solid phases. To achieve this, carbonation is studied within a thin film of an aqueous solution of calcium hydroxide, that simulates the conditions existing in porous media once most of the liquid water has evaporated. The research introduces novel approaches such as the use of specially manufactured micro-electrodes used to measure pH variations during the carbonation process. The effect of pore size on the solid phases precipitated by carbonation is investigated using a novel lime based material called nano-lime. Influence of pore-water on the hardening process of lime is studied in formulated lime using impedance spectroscopy: an electrochemical technique which is new in the study of lime based materials. Overall, results demonstrate that the micro-electrodes can operate reliably in very alkaline environments such as those produced by the dissolution of lime. Their potentiometric response, in fact, was found to be Nernstian up to pH 14. Furthermore, the electrode response proved to be sufficiently sensitive and reproducible to differentiate, on the basis of pH, between the formation of calcite and vaterite. It is likely that these micro-electrodes are currently the only analytical tools capable of monitoring high pHs in confined places and, for this reason, they can be considered highly valuable for the study of chemical processes involving very alkaline waters. The study on the role of pore-water in the hardening process of formulated lime has, instead, demonstrated the potential of impedance spectroscopy as a non-destructive technique for real time in situ monitoring of the reaction between lime and hydraulic additives.

[pt] O objetivo dessa dissertação é propor um modelo alternativo para a implementação de Sistema de Gestão da Qualidade em laboratórios de ensaios químicos que operam no ambiente universitário. O modelo proposto foi validado para o caso do Laboratório de Caracterização de Águas (LABAGUAS) do Departamento de Química da PUC-Rio. A motivação do trabalho para implementação de Sistema de Gestão da Qualidade no LABAGUAS propõe um padrão que possa ser utilizado como referência para laboratórios de ensaios químicos em ambiente universitário. A metodologia inclui revisão bibliográfica, a pesquisa documental e um estudo de caso para avaliar a implementação do Sistema Gestão da Qualidade em laboratórios de ensaios químicos em ambiente universitário, através do uso das normas gerais, de ferramentas da qualidade e de métodos de ensaios, propondo, assim, uma avaliação e melhoria dos ensaios gerenciada pelo ciclo PDCA (Planejar, Executar, Checar, Agir corretamente) na busca da melhoria contínua. Como resultados, têm-se o caso prático o ensaio determinação de pH em água a fim de avaliar as incertezas de medições analíticas, calculadas de acordo com o Guia EURACHEM e proporcionar evidências objetivas de um sistema para a garantia da qualidade. Procura-se evidenciar através de uma pesquisa, as universidades brasileiras e latinoamericanas que têm um Sistema de Gestão da Qualidade implementado em laboratórios de ensaios químicos. As principais conclusões do trabalho sinalizam que a implantação deste projeto cria oportunidades para o desenvolvimento de uma política de qualidade no Departamento de Química da PUC-RIO, estimulando o crescimento profissional e melhores condições de segurança e conforto ambiental do pessoal técnico envolvido, de forma que o laboratório possa implementar o Sistema de Gestão da Qualidade naturalmente na cultura local, sem que a liberdade acadêmica seja impactada. / [en] This work has the objective of proposing an alternative model that serves as reference for the implementation of a Quality Management System in a chemical testing lab inside universities. The proposed model was validated for the case of the Characterization Laboratory Water - LABAGUAS, belonging to the chemistry department - PUC-RIO. The motivation of the work for an implementation of a Quality Management System at LABAGUAS proposes a standard which can be used as reference for chemical testing lab inside universities. Its methodology includes a bibliographic review, research documents and the study of a case in order to evaluate the implementation of a Quality Management System in a university environment, through the use of general standards of quality tools and methods of testing, proposing an evaluation and improvement of tests managed by the PDCA (Planning, Execution, Checking and Acting), in the search of a continuous improve. As results, we have the practical case for the determination of the pH, in order to evaluate the uncertainties of analytical measurements, calculated according to the EURACHEM guide and providing objectives evidences of a system for quality assurance. The dissertation seeks to demonstrate through a survey, that the Brazilians and Latin-Americans universities which have a Quality Management System implemented in a chemical testing lab inside a university environment. The main conclusions of the study show that the implementation of this project creates opportunities for the development of a quality policy in the chemistry department of PUC-RIO, encouraging professional growth and better standards of environmental safety and comfort of the technical staff involved so that the laboratory can implement the Quality Management System course in local culture, without wich the academic freedom is impacted.