A Bioimpedance Spectroscopy Interface for EIM Based on IF-Sampling and Pseudo 2-Path SC Bandpass ∆Σ ADC

Area of Science:

• Biomedical Engineering
• Electrical Engineering
• Signal Processing

Background:

• Electrical Impedance Myography (EIM) requires accurate bioimpedance measurements.
• Existing interfaces face challenges in noise, power efficiency, and data throughput for detecting muscle contractions.

Purpose of the Study:

• To present a novel low-noise bioimpedance spectroscopy interface for EIM.
• To achieve high accuracy and efficiency in bioimpedance readings across a wide frequency range.
• To demonstrate the interface's capability for detecting muscle activity.

Main Methods:

• Utilized a direct-digital-synthesis (DDS) sinusoidal signal generator for accurate bioimpedance readings.
• Employed a quadrature low-intermediate frequency (IF) readout with low-gain IAs and bandpass ∆Σ ADCs.
• Implemented the interface in a 180 nm CMOS process.

Main Results:

• Achieved 0.7 mΩ/Hz sensitivity at 15.625 kHz and 105.8 dB SNR within a 4 Hz bandwidth.
• Demonstrated a figure-of-merit of 146.5 dB, indicating excellent performance.
• Successfully recorded EIM data during bicep brachii muscle contractions.

Conclusions:

• The proposed bioimpedance spectroscopy interface offers a low-noise, efficient solution for EIM.
• The system's performance is suitable for detecting muscle contractions in real-time.
• This technology holds significant potential for developing advanced wearable EIM systems.