A micro Electrical Impedance Tomography System for Vessel Studies

Abstract

Electrical Impedance Tomography (EIT) is a real-time imaging modality that measures and reconstructs the spatial impedance distributions inside an object under test. Based on the injection of small well know alternating currents (AC) and the measurement of resulting voltages, EIT has no known hazards and is even painless for human beings. Advantages of EIT over other classical imaging modalities are functional real-time imaging and portability, without utilizing ionic radiation. Until now EIT is mainly used as medical imaging technique, as well as for industrial and geophysical applications.This paper describes a micro EIT system which is capable to measure impedance distributions inside a small vessel and allows spatial impedance spectroscopic characterization of the vessel containments in a frequency range of 10 kHz to 250 kHz. The vessel is filled with saline or another conducting medium and is equipped with 32 electrodes. The system allows arbitrary excitation signals, generated via Direct Digital Synthesis (DDS) techniques. An embedded Field Programmable Gate Array (FPGA) System on Chip (SoC) controls the data acquisition and is able to preprocess measurement data, before the transmission via a fast USB 2.0 interface to a host PC for further analysis and image reconstruction.Keywordsmulti-frequency EITField-Programmable Gate-Array (FPGA) System on Chip (SoC)Direct Digital Synthesis