Desenvolvimento de um sistema microcontrolado para a aquisição de bioimpedância

Abstract

This work presents the development of a microcontrolled system for the acquisition of bioimpedance of post-mortem animal tissue. I also presents the concepts related to bioimpedance and the electrical characteristics of biological tissues and bioimpedance measurement techniques, which are concepts essential for understanding the proposed system. From these features, a microcontroller from STMicroelectronics STM32F4 family was chosen because of its availability and its performance characteristics, which is necessary to calculate the Discrete Fourier Transform with less time and cost for this computer system. Through DFT it is obtained the frequency components of the excitation signal and response of the bioelectrical impedance. From these phasors it is possible to calculate the bioimpedance. Experiments were conducted using models of bioimpedance in order to evaluate the response of the proposed measurement system. From these experiments it was obtained the analyzer measurement range, comprising frequencies from 30 to 300 kHz, impedance module from 100 Ω to 900 K Ω and phase angle from 0° to 180°, with less measurement error than 4%, and phase error of up to 10% for phase lower than 1° and modulus above 200 kΩ. Finally, results are presented and commented.