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

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 µA 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. OPEN ACCESSElectronics 2015, 4 508

Galvanically Decoupled Current Source Modules for Multi-Channel Bioimpedance Measurement Systems

“…Since the quantitative impact of this effect is not predictable and changes over time, it has to be prevented. An often implemented solution for this problem is the compartmentation in time domain by multiplexing the excitation currents [1,7]. A major advantage of this realization is that just one current source circuit is necessary.…”

“…Transient measurements can, for example, be executed for respiration monitoring or detection of muscle contractions [5,6]. Additionally, in some applications, such as the electrical impedance tomography (EIT) imaging technique [7,8], multi-channel measurement devices are required. One further application is the detection of the arterial pulse wave at different positions of the human body to obtain information about its velocity and changes in pulse morphology [1,[9][10][11].…”

Design and development of electrical impedance tomography system with 32 electrodes and microcontroller

“…The signal transmission over the system is bidirectional [5]. Firstly, in the initialization step, the configuration data from the user interface is transferred to the microcontroller.…”

FPGA and SoC Devices Applied to New Trends in Image/Video and Signal Processing Fields

“…However, the introduced EIT system measures the complete spectrum ranging from 10 to 380 kHz for each transfer impedance over time, achieving an additional dimension of information for the subsequent image reconstruction. In [5], the authors present a FPGA-based multi-frequency EIT system for time-resolved measurements of conductivity distributions in living tissue. The system acquires complex impedance values very precisely.…”