Low-noise current excitation sub-system for medical EIT

Hugh Mccann, M. Rafiei-Naeini, H. McCann

    Research output: Contribution to journalArticlepeer-review

    Abstract

    Electrical impedance tomography (EIT) has many potential applications in medicine. The sensitivity and spatial resolution of EIT can be enhanced significantly by increasing the measurement signal-to-noise ratio (SNR), to which a significant contribution is made by the SNR of the current excitation sub-system. In this paper we present a prototype EIT current excitation sub-system with 80 dB SNR, exploiting both digital and analogue techniques. It uses digital waveform synthesis, a 16-bit DAC and subsequent reconstruction filter, to drive an enhanced Howland current source. Detailed analysis and testing of the current sub-system are presented. Its output impedance is 10 MΩ for different load impedances, varying slowly over the frequency range from 10 kHz up to 4 MHz. © 2008 Institute of Physics and Engineering in Medicine.
    Original languageEnglish
    Pages (from-to)S173-S184
    JournalPhysiological Measurement
    Volume29
    Issue number6
    DOIs
    Publication statusPublished - 1 Jun 2008

    Keywords

    • Analogue
    • Current source
    • Digital
    • EIT
    • Low-noise

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