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 language | English |
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Pages (from-to) | S173-S184 |
Journal | Physiological Measurement |
Volume | 29 |
Issue number | 6 |
DOIs | |
Publication status | Published - 1 Jun 2008 |
Keywords
- Analogue
- Current source
- Digital
- EIT
- Low-noise