Precision constant current source for electrical impedance tomography

Author

Lee, Jeong Whan ; Oh, Tong In ; Paek, Sang Min ; Lee, Jae Sang ; Woo, Eung Je

Author_Institution

Coll. of Electron. & Inf., Kyung Hee Univ., Seoul, South Korea

Volume

2

fYear

2003

fDate

17-21 Sept. 2003

Firstpage

1066

Abstract

In electrical impedance tomography (EIT), we inject currents through electrodes placed on the surface of a subject and try to reconstruct cross-sectional resistivity images. This requires a precision constant current source. In this paper, we present a design and performance analysis of a constant current source using an FPGA-based waveform generator and improved Rowland current pump circuit. The designed current source was implemented and tested to verify the total harmonic distortion of 0.0907% and amplitude stability of 0.2361%. The output impedance of the current source was bigger than 64 MΩ at dc and smaller than 500 KΩ at 50 KHz. We need to further improve the output impedance at the frequency of 50 KHz or higher employing a better method of stray capacitance cancellation.

Keywords

biomedical electrodes; constant current sources; electric impedance imaging; field programmable gate arrays; harmonic distortion; image reconstruction; waveform generators; 50 KHz; 500 Kohm; 64 Mohm; Rowland current pump circuit; cross-sectional resistivity image; electrical impedance tomography; output impedance; performance analysis; precision constant current source; stray capacitance cancellation; total harmonic distortion; Circuit testing; Conductivity; Electrodes; Image reconstruction; Performance analysis; Signal generators; Surface impedance; Surface reconstruction; Tomography; Total harmonic distortion;

fLanguage

English

Publisher

ieee

Conference_Titel

Engineering in Medicine and Biology Society, 2003. Proceedings of the 25th Annual International Conference of the IEEE

ISSN

1094-687X

Print_ISBN

0-7803-7789-3

Type

conf

DOI

10.1109/IEMBS.2003.1279429

Filename

1279429