On the application of frequency selective common mode feedback for multifrequency EIT

Area of Science:

• Electrical Engineering
• Biomedical Engineering
• Signal Processing

Background:

• Common mode voltages pose significant challenges in electrical impedance tomography (EIT) and bioimpedance analysis.
• Imbalances in current drives, electrode connections, and body impedance to ground contribute to these common mode effects.

Purpose of the Study:

• To analyze common mode feedback for current drives in bioimpedance applications.
• To investigate the effectiveness of frequency-selective narrowband common mode feedback.
• To demonstrate multifrequency application capabilities.

Main Methods:

• Formalized analysis of current and voltage feedback mechanisms.
• Consideration of common mode effects from various sources of imbalance.
• Experimental demonstration of narrowband feedback for dual simultaneous current drives.

Main Results:

• Achieved a 62 dB reduction in current feedback.
• Achieved a 31 dB reduction in voltage feedback.
• Demonstrated effective feedback across frequencies from 50 kHz to 1 MHz.

Conclusions:

• Narrowband common mode feedback effectively mitigates common mode voltages in EIT.
• The experimental results validate the proposed feedback strategy for multifrequency bioimpedance measurements.
• Standard components can be utilized to achieve substantial noise reduction.