Amplificador de instrumentação aplicado na medicina: aquisição e tratamento de sinais

Abstract

Operational amplifiers (AOs) are integrated circuits designed to perform basic mathematical operations such as sum, subtraction, differentiation and integration using analog electronics. The technological advancement and new types of printed circuits developed in the last decades have provided incredible advances for the AO’s, which have made them smaller than their predecessors and with features much closer to the ideal, such as very high input impedance (approximately 1012Ω), and impedance approximately null with field effect transistor at the output, which isolates the voltage received by the circuit, making it a functional component. Therefore, due to the versatility of the AO’s, it is still used in digital circuit interfaces since it is a complete analogue interface, where it stands out its amplification efficiency for real-time signal processing, making the AO irreplaceable in several applications and successful in the electro/electronic areas. In physics applied to medicine, they aid in the measurement of bioelectrical signals, which can be analyzed and recorded, enabling us to know and follow the electrical signals that the body produces. Thus, this work was dedicated to the production of a biomedical amplifier composed of four operational amplifiers of two channels, which, together, form an instrumentation amplifier, with the purpose of acquiring, with the help of a bench oscilloscope, bioelectrical signals from the heart beats, simulated by a function generator with attenuation and treat noise by building a capacitive filter. Several measurements were made regarding the application and efficiency of the AO’s and then compared with the theory, which allowed us to conclude that the TL074CN operational amplifier is efficient for the amplification of the bioelectrical signals.