Low-noise current excitation sub-system for medical EIT

Area of Science:

• Biomedical Engineering
• Medical Imaging Technology

Background:

• Electrical impedance tomography (EIT) offers diverse medical applications.
• Enhancing EIT's sensitivity and spatial resolution is crucial for improved diagnostic capabilities.
• The signal-to-noise ratio (SNR) of the current excitation sub-system significantly impacts overall EIT performance.

Purpose of the Study:

• To develop and characterize a high-SNR current excitation sub-system for EIT.
• To improve the SNR of EIT systems by optimizing the current excitation sub-system.
• To demonstrate the feasibility of achieving 80 dB SNR in an EIT current excitation sub-system.

Main Methods:

• Utilized a combination of digital and analogue techniques for high SNR.
• Employed digital waveform synthesis with a 16-bit DAC and reconstruction filter.
• Drove an enhanced Howland current source with the synthesized waveform.

Main Results:

• Achieved an 80 dB SNR in the prototype EIT current excitation sub-system.
• The sub-system demonstrated a high output impedance of 10 MOmega across various load impedances.
• Stable performance was observed over a frequency range from 10 kHz to 4 MHz.

Conclusions:

• The developed EIT current excitation sub-system significantly enhances SNR.
• This high-performance sub-system is expected to improve EIT sensitivity and spatial resolution.
• The prototype validates the effectiveness of combined digital and analogue techniques for advanced EIT instrumentation.