Comparative Study of Measurement Methods for Embedded Bioimpedance Spectroscopy Systems

Area of Science:

• Electrical Engineering
• Biomedical Engineering
• Signal Processing

Background:

• Bioimpedance spectroscopy (BIS) is crucial for analyzing impedance changes across frequencies.
• Various BIS measurement techniques exist, including gain phase detector (GPD), IQ demodulation, and fast Fourier transform (FFT).
• A systematic comparison of these BIS measurement methods is lacking.

Purpose of the Study:

• To systematically compare GPD, IQ demodulation, and FFT methods for BIS measurements.
• To evaluate performance based on accuracy, complexity, and power consumption.
• To identify the optimal BIS measurement technique for specific applications.

Main Methods:

• Simulations and experimental studies were conducted using identical signal generators and voltage-controlled current sources (VCCS).
• Three devices under test (DUTs) mimicking biological tissue impedance were used.
• Performance was assessed against a laboratory impedance analyzer, focusing on magnitude and phase accuracy, signal processing, hardware complexity, and power consumption.

Main Results:

• The FFT-based BIS system demonstrated superior accuracy in both amplitude and phase measurements.
• FFT also exhibited the lowest hardware complexity and power consumption.
• Conversely, the FFT method requires significantly higher software complexity compared to GPD and IQ demodulation.

Conclusions:

• The FFT method is highly accurate and efficient for bioimpedance spectroscopy, particularly regarding hardware and power.
• Despite higher software demands, the FFT approach presents a compelling option for advanced BIS applications.
• This comparative study provides valuable insights for selecting appropriate BIS measurement techniques.