Dependencia térmica de las propiedades eléctricas del tejido pulmonar a frecuencias entre 10 Hz y 100 kHz.

One of the main challenges in the study of the interaction of electromagnetic fields with biological tissues is the precise knowledge of the electric (permittivity and electrical conductivity) and thermal (rate of heat transfer, thermal conductivity, heat production rate, and mass density) parameters of these. They determine the ways in which current flows and heat depositions takes place and thus represent crucial input data for the modeling and simulation of electromagnetic fields and its thermal effect on tissues. In this work they are presented for the first time the results of the characterization of the thermal dependence of the electric parameters of the porcine lung tissue during its heating in vitro from 37 to 70 °C with a heating rate of 5 °C/min in the frequency range from 10 Hz to 100 kHz. For this, it was built and validated an experimental setup based on a Lock-in amplifier, coupled to a computer, and they were developed the corresponding data acquisition and processing software. It was observed that up to a temperature of about 50 °C the conductivity of the tissue increases linearly with the temperature for all the frequencies with an average rate of 1.810%/°C, while the permittivity decreases with an average rate of -0.563%/°C, at frequencies above 100 Hz, and increases with an average rate of 6.100%/°C, at frequencies below 1 kHz. [ABSTRACT FROM AUTHOR]