Implementa??o de um sistema de eletrodos microfabricados para registro e estimula??o neural extracelular in vitro

• Main Author: Vidor, Carolina de Barros
• Other Authors: Papal?o, Ricardo Meurer
• Format: Others
• Language: Portuguese
• Published: Pontif?cia Universidade Cat?lica do Rio Grande do Sul 2015
• Subjects: ENGENHARIA DE MATERIAIS; MICROELETR?NICA; MICROSCOPIA ELETR?NICA; MICROSCOPIA ?PTICA; ELETROFISIOLOGIA; EPILEPSIA; CNPQ::ENGENHARIAS
• Online Access: http://tede2.pucrs.br/tede2/handle/tede/3260

Made available in DSpace on 2015-04-14T13:59:08Z (GMT). No. of bitstreams: 1 459620.pdf: 5079443 bytes, checksum: 08c93370bfca9d36a99775d85a58b7d2 (MD5) Previous issue date: 2014-06-03 === The main goal of this work was to implement a microfabricated electrode system for in vitro neural stimulation and recording. The MEA biosensor structural characterization was obtained by optical and scanning electrical microscopy images. Qualitative analysis of the chemical composition was made through energy-dispersive X-ray spectroscopy. Analysis of the noise level was conducted by evaluating the RMS value of the potentials recorded with sensors filled with standard saline solution. An electronic interface between a MEA and a conventional data acquisition system with eight channels was constructed and performance tests of the built interface were conducted. Installation of a MEA commercial system was carried out and preliminary tests were performed by experimenting with rodent neuronal cell culture and brain slices. An attempt was made to adapt a conventional perfusion system by peristaltic pump to the MEA system; however, the results were unsatisfactory due to the high noise level of the recordings. Experimental procedures related to the proper handling of MEAs were defined, and the influence of different parameters involved in experimentation with MEAs was investigated. Finally, the data analysis of cell culture recordings indicated detection of local field potentials (LFPs) of greater amplitude, higher counts of spikes and higher spike frequency in the records obtained with standard culture medium compared to those obtained with extracellular electrophysiological solution. The data analysis of cortical slices recordings indicated the detection of a greater number of spikes per minute, higher spike frequency and greater peak-to-peak spikes amplitudes by the microelectrodes that have captured LFPs of greater magnitude. === O objetivo principal deste trabalho foi implementar um sistema de eletrodos microfabricados para registro e estimula??o neural extracelular in vitro. A estrutura dos arranjos de microeletrodos (MEAs) foi caracterizada atrav?s de imagens por microscopia ?ptica e por microscopia eletr?nica de varredura. A an?lise qualitativa da composi??o qu?mica foi feita por espectroscopia de raios X por energia dispersiva e a an?lise do n?vel de ru?do foi realizada atrav?s da avalia??o do valor RMS dos potenciais registrados com os sensores preenchidos com solu??o salina padr?o. Uma interface eletr?nica entre um MEA e um sistema de aquisi??o de dados convencional com oito canais foi constru?da e testes de desempenho foram realizados. Um sistema MEA comercial foi instalado e validado atrav?s de experimenta??o com cultura neuronal e fatias de c?rebro de roedor. A tentativa de adapta??o de um sistema convencional de perfus?o por bomba perist?ltica ao sistema MEA mostrou-se insatisfat?ria devido ao alto n?vel de ru?do dos registros. Procedimentos experimentais relacionados ao correto manuseio dos MEAs foram definidos, e investigou-se a influ?ncia de diferentes par?metros sobre a atividade detectada com os sensores. Finalmente, a an?lise dos dados com cultura celular indicou detec??o de potenciais de campo locais (PCLs) de maior amplitude, maior contagem de spikes e maior freq??ncia de atividade nos registros obtidos com meio de cultura padr?o. Os dados com fatias de tecido indicaram a detec??o de maior n?mero de spikes por minuto, de maior freq??ncia de atividade e de maior amplitude pico-a-pico dos spikes nos microeletrodos que captaram PCLs de maior amplitude.