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BioMed Research International
Volume 2014, Article ID 143461, 8 pages
http://dx.doi.org/10.1155/2014/143461
Research Article

Development of a Stair-Step Multifrequency Synchronized Excitation Signal for Fast Bioimpedance Spectroscopy

1Department of Precision and Instrumentation Engineering, Xi’an University of Technology, Xi’an 710048, China
2Department of Electronic Engineering, Xi’an University of Technology, Xi’an 710048, China
3Department of Instrumentation Science and Technology, Hunan University, Changsha 410082, China

Received 19 November 2013; Revised 8 January 2014; Accepted 8 January 2014; Published 19 February 2014

Academic Editor: Ali Khraibi

Copyright © 2014 Yuxiang Yang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Wideband excitation signal with finite prominent harmonic components is desirable for fast bioimpedance spectroscopy (BIS) measurements. This work introduces a simple method to synthesize and realize a type of periodical stair-step multifrequency synchronized (MFS) signal. The Fourier series analysis shows that the p-order MFS signal has constant 81.06% energy distributed equally on its p   th primary harmonics. The synthesis principle is described firstly and then two examples of the 4-order and 5-order MFS signals, and , are synthesized. The method to implement the MFS waveform based on a field-programmable gate array (FPGA) and a digital to analog converter (DAC) is also presented. Both the number and the frequencies of the expected primary harmonics can be adjusted as needed. An impedance measurement experiment on a RC three-element equivalent model is performed, and results show acceptable precision, which validates the feasibility of the MFS excitation.