• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 2
  • Tagged with
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Desenvolvimento de um protótipo de neuroestimulador bifásico para pacientes acometidos de dor crônica

Oliveira, Mileny Ximenes 22 August 2016 (has links)
Dissertação (mestrado)—Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Elétrica, 2016. / Submitted by Fernanda Percia França (fernandafranca@bce.unb.br) on 2016-11-25T15:03:01Z No. of bitstreams: 1 2016_MilenyXimenesOliveira.pdf: 101405168 bytes, checksum: ff0e47e95265c1b5f3854db1a12db020 (MD5) / Approved for entry into archive by Raquel Viana(raquelviana@bce.unb.br) on 2017-01-30T18:32:27Z (GMT) No. of bitstreams: 1 2016_MilenyXimenesOliveira.pdf: 101405168 bytes, checksum: ff0e47e95265c1b5f3854db1a12db020 (MD5) / Made available in DSpace on 2017-01-30T18:32:27Z (GMT). No. of bitstreams: 1 2016_MilenyXimenesOliveira.pdf: 101405168 bytes, checksum: ff0e47e95265c1b5f3854db1a12db020 (MD5) / A dor crônica é caracterizada por se estender durante um longo período de tempo e não apresentar respostas satisfatórias a terapias convencionais, como as medicamentosas. Neste contexto a Estimulação Medular Espinhal (EME) se apresenta como uma terapia invasiva que se baseia em substituir a experiência que o paciente tem de dor por outra sensação menos incômoda e debilitante. Hoje existem alguns dispositivos que realizam tal procedimento, no entanto, todos são importados e não oferecem qualquer documentação sobre seu funcionamento e como reagem a diferentes impedâncias do tecido estimulado eletricamente. Sendo assim, este trabalho expõe o desenvolvimento de um protótipo de neuroestimulador implantável, capaz de estimular diferentes cargas resistivas e utilizar parâmetros de amplitude de corrente, largura de pulso e frequência pré estabelecidas pelo usuário. Além do canal de estimulação, este documento apresenta também o desenvolvimento do dispositivo responsável pela comunicação sem fio dos parâmetros de estimulação ao estimulador. A topologia desenvolvida se baseia em uma fonte de corrente controlada por tensão, responsável por gerar um sinal de corrente contínua. E a tensão bifásica é obtida com chaveamento da corrente, executada com chaves analógicas. Nos experimentos in vitro foram observadas as formas de onda e o comportamento linear dos canais de estimulação para diferentes cargas resistivas, validando a metodologia utilizada. Durante o desenvolvimento da pesquisa fatores relacionados a consumo e dimensões reduzidas também foram considerados, no entanto a redução máxima destes aspectos ficam a cargo de trabalhos futuros, bem como testes realizados in vivo. / saChronic pain is characterized for extending over a long period of time and for not presenting satisfactory answers to conventional therapies, such as medicaments therapies. In this context, the Spinal Cord Stimulation (SCS) is an invasive therapy that is based on replacing the pain experience that the patient has for another sensation less troublesome and debilitating. Today there are some devices that perform such procedure, however, all of them are imported and do not offer any documentation about its behavior and how they react to different impedances of electrically stimulated tissue. Therefore, this work exposes the development of the implantable neurostimulator prototype, able to stimulate different resistive loads and use parameters pre-established by user, such as: current amplitude, pulse width and frequency. Besides the stimulation channel, this document also presents the development of the device responsible for the wireless communication of stimulation parameters to the stimulator. The topology developed is based on a voltagecontrolled current source, responsible for generating a direct current signal. The biphasic signal is obtained through current switching, performed by analog switches. The waveform and the linear behavior of the stimulation channels for different resistive loads were observed by in vitro experiments, validating the methodology used. Factors related to consumption and reduced dimensions were considered throughout the research, however the maximum reduction of these aspects shall be borne by future work, as well as in vivo tests.
2

Contribui??es para a an?lise de sinais neuronais e biom?dicos

Santos, V?tor Lopes dos 03 March 2011 (has links)
Made available in DSpace on 2014-12-17T14:55:49Z (GMT). No. of bitstreams: 1 VitorLS_DISSERT.pdf: 1833534 bytes, checksum: 72ebc7d9d8be6ba8ae53eaad106afa8d (MD5) Previous issue date: 2011-03-03 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / Following the new tendency of interdisciplinarity of modern science, a new field called neuroengineering has come to light in the last decades. After 2000, scientific journals and conferences all around the world have been created on this theme. The present work comprises three different subareas related to neuroengineering and electrical engineering: neural stimulation; theoretical and computational neuroscience; and neuronal signal processing; as well as biomedical engineering. The research can be divided in three parts: (i) A new method of neuronal photostimulation was developed based on the use of caged compounds. Using the inhibitory neurotransmitter GABA caged by a ruthenium complex it was possible to block neuronal population activity using a laser pulse. The obtained results were evaluated by Wavelet analysis and tested by non-parametric statistics. (ii) A mathematical method was created to identify neuronal assemblies. Neuronal assemblies were proposed as the basis of learning by Donald Hebb remain the most accepted theory for neuronal representation of external stimuli. Using the Marcenko-Pastur law of eigenvalue distribution it was possible to detect neuronal assemblies and to compute their activity with high temporal resolution. The application of the method in real electrophysiological data revealed that neurons from the neocortex and hippocampus can be part of the same assembly, and that neurons can participate in multiple assemblies. (iii) A new method of automatic classification of heart beats was developed, which does not rely on a data base for training and is not specialized in specific pathologies. The method is based on Wavelet decomposition and normality measures of random variables. Throughout, the results presented in the three fields of knowledge represent qualification in neural and biomedical engineering / Following the new tendency of interdisciplinarity of modern science, a new field called neuroengineering has come to light in the last decades. After 2000, scientific journals and conferences all around the world have been created on this theme. The present work comprises three different subareas related to neuroengineering and electrical engineering: neural stimulation; theoretical and computational neuroscience; and neuronal signal processing; as well as biomedical engineering. The research can be divided in three parts: (i) A new method of neuronal photostimulation was developed based on the use of caged compounds. Using the inhibitory neurotransmitter GABA caged by a ruthenium complex it was possible to block neuronal population activity using a laser pulse. The obtained results were evaluated by Wavelet analysis and tested by non-parametric statistics. (ii) A mathematical method was created to identify neuronal assemblies. Neuronal assemblies were proposed as the basis of learning by Donald Hebb remain the most accepted theory for neuronal representation of external stimuli. Using the Marcenko-Pastur law of eigenvalue distribution it was possible to detect neuronal assemblies and to compute their activity with high temporal resolution. The application of the method in real electrophysiological data revealed that neurons from the neocortex and hippocampus can be part of the same assembly, and that neurons can participate in multiple assemblies. (iii) A new method of automatic classification of heart beats was developed, which does not rely on a data base for training and is not specialized in specific pathologies. The method is based on Wavelet decomposition and normality measures of random variables. Throughout, the results presented in the three fields of knowledge represent qualification in neural and biomedical engineering

Page generated in 0.0682 seconds