A FPGA-Based Broadband EIT System for Complex Bioimpedance Measurements -- Design and Performance Estimation

TL;DR

This paper introduces an FPGA-based broadband EIT system capable of complex, multi-frequency bioimpedance measurements with high sample rates, suitable for real-time imaging and human studies.

Contribution

The work presents a novel FPGA-based multi-frequency EIT system with high measurement speed and flexible excitation signals for bioimpedance imaging.

Findings

Successfully measured impedance spectra from phantoms and human thorax.

Achieved up to 3480 spectra per second sample rate.

Demonstrated system's capability with various excitation signals.

Abstract

Electrical impedance tomography (EIT) is an imaging method that is able to estimate the electrical conductivity distribution of living tissue. This work presents a field programmable gate array (FPGA)-based multi-frequency EIT system for complex, time-resolved bioimpedance measurements. The system has the capability to work with measurement setups with up to 16 current electrodes and 16 voltage electrodes. The excitation current has a range of about 10 $\mu$A to 5 mA, whereas the sinusoidal signal used for excitation can have a frequency of up to 500 kHz. Additionally, the usage of a chirp or rectangular signal excitation is possible. Furthermore, the described system has a sample rate of up to 3480 impedance spectra per second (ISPS). The performance of the EIT system is demonstrated with a resistor-based phantom and tank phantoms. Additionally, first measurements taken from the human thorax during a breathing cycle are presented.