Sistema eletrônico de aquisição de sinais de um eletrocardiograma

• Autor(a) principal: Vilela, Letícia Michele Dal’Cól
• Data de Publicação: 2020
• Tipo de documento: Trabalho de conclusão de curso
• Idioma: por
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://hdl.handle.net/11449/214070
• topic: Amplificadores eletrônicos; Eletrocardiografia; Engenharia biomédica; Filtros elétricos ativos

Electrocardiography is a health examination in the area of cardiology in which it is recorded the variation of the electrical potentials generated by the electrical activity of the heart, the Electrocardiogram (ECG). To perform this examination, electrodes are placed at specific points on the body in order to record the electrical activity caused by the variation in the cytosolic concentration of calcium, sodium and potassium ions. Subsequently, the diagnosis is made by the information of peak of waves and intervals of time of the obtained signal. The ECG can be obtained in a non-invasive way (external to the human body), with safe and low cost, and has as main advantage to provide quick and accurate information for analysis and diagnosis of cardiovascular anomalies. Once this electrical activity results in small amplitude waves (from 0.5 to 4 mV) and low frequency (0.05 to 100 Hz), the signal reading becomes prejudiced, because it is affected by multiple interference source. In the technical point of view, the instrumentation required for the acquisition, amplification and conditioning of the ECG signal consists in the classical pratical example in a instrumentation system. The system developed for the cardiac electrical activity acquisition consists in the utilization of electrodes, that are connected obeying the principle of Einthoven’s three derivations; instrumentation amplifier, INA 121; and finally the fourth Bessel topology, Notch and bandpass filters for noise removal, aiming the 0.5 Hz to 40 Hz monitoring. In these cases were utilized the operational amplifier LM 741. The instrumentation amplifier was utilized maintaining the elevated impedance input, elevated rejection to common mode signals, in addition to an adjustable differential gain, however in this case, the adopted gain is 100 V/V. The Notch filter was implemented for the removal of the 60 Hz noise from electric network and the bandpass filter for removal of the base line oscillation, in addition to biologic interference.