Desenvolvimento de um aparelho de eletroencefalografia mobile de baixo custo
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Data
2019-04-30
Autores
Otoni, Julliano da Silva
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Universidade Estadual Paulista (Unesp)
Resumo
O objetivo deste trabalho foi produzir um dispositivo coletor de biopotenciais por EEG de baixo custo. Como características o protótipo apresentou alta imunidade a ruído, faixa de frequência de trabalho e tensão, seguindo as especificações necessárias para a coleta dos sinais EEG. O circuito eletrônico e o roteamento foram desenvolvidos no software Eagle R e então a placa foi construída pelo método fotográfico com posterior corrosão por percloreto de ferro e solda-gem manual dos componentes. O circuito montado é composto por: amplificadores diferenciais configurados com um ganho na ordem de 169,66, filtros de frequência intercalados e um mi-crocontrolador ESP32@ que munido de conversor analógico-digital foi configurado para uma amostragem de 356 amostras por segundo e resolução de 12 bits, o que possibilitou leituras com passos de 2,198x10-4 V. Os filtros foram projetados para atuar na redução de ruidos contidos na faixa de 50 a 60Hz. O funcionamento do dispositivo móvel microcontrolado teve seu funciona-mento comprovado através do método de detecção de ondas alfa, ondas estas que alteram suas intensidade quando nos encontramos concentrados com os olhos abertos ou fechados. A captura de ondas alfa compreendidas entre 8 a 13 Hz foi validada nas seguintes condições: 1 minuto com os olhos fechados (alta atividade) e 1 minuto com os olhos abertos (baixa atividade). O dispositivo produzido mostrou-se promissor como uma alternativa de baixo custo e com simpli-cidade de produção, quando comparado aos modelos disponíveis no mercado para captura de sinais EEG.
The objective of this work was to produce a low cost EEG biopotential collecting device. As characteristics the prototype presented high immunity to noise, working frequency range and voltage, following the specifications required for the collection of EEG signals. Electronic circuit and routing were developed in the Eagle R software and the plate was then constructed by the photographic method with subsequent iron perchloride corrosion and manual soldering of the components. The assembled circuit consists of: differential amplifiers configured with a gain of the order of 169.66, frequency filters interleaved and an ESP32 @ microcontroller which has an analog-to-digital converter configured for a sampling of 356 samples per second and resolution of 12 bits, which allowed for readings with steps of 2.198x10-4 V. The filters were designed to act in the reduction of noise contained in the range of 50 to 60Hz. The operation of the microcontrolled mobile device has proven its function through the method of detecting alpha waves, waves that change their intensity when we are concentrated with the eyes open or closed. The capture of alpha waves between 8 and 13 Hz was validated under the following conditions: 1 minute with eyes closed (high activity) and 1 minute with eyes open (low activity). The device produced was promising as a low-cost, simplified production alternative when compared to models available on the market for EEG signal capture.
The objective of this work was to produce a low cost EEG biopotential collecting device. As characteristics the prototype presented high immunity to noise, working frequency range and voltage, following the specifications required for the collection of EEG signals. Electronic circuit and routing were developed in the Eagle R software and the plate was then constructed by the photographic method with subsequent iron perchloride corrosion and manual soldering of the components. The assembled circuit consists of: differential amplifiers configured with a gain of the order of 169.66, frequency filters interleaved and an ESP32 @ microcontroller which has an analog-to-digital converter configured for a sampling of 356 samples per second and resolution of 12 bits, which allowed for readings with steps of 2.198x10-4 V. The filters were designed to act in the reduction of noise contained in the range of 50 to 60Hz. The operation of the microcontrolled mobile device has proven its function through the method of detecting alpha waves, waves that change their intensity when we are concentrated with the eyes open or closed. The capture of alpha waves between 8 and 13 Hz was validated under the following conditions: 1 minute with eyes closed (high activity) and 1 minute with eyes open (low activity). The device produced was promising as a low-cost, simplified production alternative when compared to models available on the market for EEG signal capture.
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Palavras-chave
Eletroencefalografia, Ondas Alfa, ESP32, Arduino, Electroencephalography, Alpha Waves