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A fully parallel multi-frequency EIT system with flexible electrode configuration: KHU Mark2.
MedLine Citation:
PMID:  21646706     Owner:  NLM     Status:  In-Data-Review    
Abstract/OtherAbstract:
We report the development of a new multi-frequency electrical impedance tomography (EIT) system called the KHU Mark2. It is descended from the KHU Mark1 in terms of technical details such as digital waveform generation, Howland current source with multiple generalized impedance converters and digital phase-sensitive demodulators. New features include flexible electrode configurations to accommodate application-specific requirements, multiple independent current sources and voltmeters for fully parallel operations, improved data acquisition speeds for faster frame rates and compact mechanical design. Given an electrode configuration, we can design an analog backplane in such a way that both current injections and voltage measurements can be done without using any switch. The KHU Mark2 is based on an impedance measurement module (IMM) comprising a current source and a voltmeter. Using multiple IMMs, we can construct a multi-channel system with 16, 32 or 64 channels, for example. Adopting a pipeline structure, it has the maximum data acquisition speed of 100 scans s(-1) with the potential to detect fast physiological changes during respiration and cardiac activity. Measuring both in-phase and quadrature components of trans-impedances at multiple frequencies simultaneously, the KHU Mark2 is apt at spectroscopic EIT imaging. In this paper, we describe its design, construction, calibration and performance evaluation. It has about 84 dB signal-to-noise ratio and 0.5% reciprocity error. Time-difference images of an admittivity phantom are presented showing spectroscopic admittivity images. Future application studies using the KHU Mark2 are briefly discussed.
Authors:
Tong In Oh; Hun Wi; Do Yub Kim; Pil Joong Yoo; Eung Je Woo
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Publication Detail:
Type:  Journal Article     Date:  2011-06-07
Journal Detail:
Title:  Physiological measurement     Volume:  32     ISSN:  1361-6579     ISO Abbreviation:  Physiol Meas     Publication Date:  2011 Jul 
Date Detail:
Created Date:  2011-06-07     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9306921     Medline TA:  Physiol Meas     Country:  England    
Other Details:
Languages:  eng     Pagination:  835-49     Citation Subset:  IM    
Affiliation:
Impedance Imaging Research Center and Department of Biomedical Engineering, Kyung Hee University, Korea.
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