Wideband Chirp Excitation Source for Bioelectrical Impedance Spectrum Tomography

摘要

Electrical impedance spectrum tomography (EIST) has become an important tool for biomedical and electrochemical research. Compared with the existing electrical impedance tomography, EIST can reveal the richer frequency information with higher resolution on the electrical properties analysis of biological materials, including amplitude and phase shift over a continuous frequency range. To achieve these functions, a dedicated hardware system must be developed to meet the requirement of wide frequency range and flat spectral characteristic. In this paper, a wideband chirp signal excitation source was designed to drive bioimpedance tissues. According to mathematical mechanism of a chirp signal, high quality chirp signal was generated with field programmable gate array and direct digital synthesis method. Furthermore, on the basis of single resistance calibration, experiments based on three elements impedance loads were executed to verify the feasibility and performance of the excitation source design. The measured results illustrate that the current excitation source has a qualified driving capability. Sensitive spectral response of amplitude and phase shift can be obtained by means of wideband chirp signal.