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Doctoral Thesis
DOI
https://doi.org/10.11606/T.18.2023.tde-22062023-081037
Document
Author
Full name
Amélia Moreira Santos
Institute/School/College
Knowledge Area
Date of Defense
Published
São Carlos, 2023
Supervisor
Committee
Altafim, Ruy Alberto Correa (President)
Fernandes, Ricardo Augusto Souza
Flauzino, Rogério Andrade
Ribeiro, Cacilda de Jesus
Santos, Lucas Fugikawa
Title in Portuguese
Sensor de corrente baseado na tecnologia de magneto-piezoeletretos termoformados
Keywords in Portuguese
magnetoeletretos
piezoeletricidade
polímeros
sensores
Abstract in Portuguese
Os piezoeletretos, conhecidos também como filmes eletromecânicos (Emfit), receberam considerável atenção após a demonstração de que poderiam exibir alta piezoeletricidade. Neste contexto, o escopo desta tese foi desenvolver uma nova categoria de sensores de correntes elétricas a partir da modelagem de piezoeletretos com canaletas termoformadas, porém com características magnéticas como aperfeiçoamento. Esta característica magnética originou uma nova classe de piezoeletretos denominada Magneto-Piezoeletretos Termoformados (MPTs). A primeira fase desta pesquisa foi direcionada ao desenvolvimento, escolha dos materiais a serem utilizados e na construção dos MPTs. A segunda fase foi direcionada aos ensaios experimentais para as análises das propriedades físicas, do Método Berlincourt e para os ensaios de sensibilidade em campos magnéticos produzidos por ímãs e correntes elétricas. Os resultados comprovaram que o MPTs interagiram com campos magnéticos proporcionais aos ímãs e às correntes elétricas aplicadas. Assim, confirmou-se que houve geração de cargas elétricas devida à polarização macroscópica entre o MPTs e os campos magnéticos, bem como a constatação do efeito piezoelétrico direto. Por fim, constatou-se que a camada de material magnetoestritivo adicional não apenas otimizou a piezoeletricidade nos MPTs, aumentando consideravelmente os coeficientes piezoelétricos e piezo-magnéticos, como também permitiu que estes respondessem a campos magnéticos externos.
Title in English
Current sensor based on magneto-piezoelectret thermoformed technology
Keywords in English
magnetoelectrets
piezoelectricity
polymers
sensors
Abstract in English
Piezoelectrets, also known as electromechanical films (Emfit), received considerable attention after demonstrating that they could exhibit high piezoelectricity. In this context, the scope of this thesis was to develop a new category of electrical current sensors from the modeling of piezoelectrets with thermoformed channels, but with magnetic characteristics as an improvement. This magnetic characteristic gave rise to a new class of piezoelectrets called Thermoformed Magneto-Piezoelectrets (MPTs). The first phase of this research was directed toward the development, choice of materials to be used, and construction of the MPTs. The second phase involved experimental tests for the analysis of physical properties, the Berlincourt Method, and sensitivity tests in magnetic fields produced by magnets and electric currents. The results proved the MPTs interacted with magnetic fields proportional to the magnets and applied electric currents. It was confirmed that electric charges were generated because of the macroscopic polarization between the MPTs and the magnetic fields, as well as the observation of the direct piezoelectric effect. Lastly, it was found that the additional magnetostrictive material layer not only optimized the piezoelectricity in the MPTs, supersizing the piezoelectric and piezomagnetic coefficients, but also allowed them to respond to external magnetic fields.
 
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Publishing Date
2023-06-23
 
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