Impedance-Readout Integrated Circuits for Electrical Impedance Spectroscopy: Methodological Review

Area of Science:

• Electrical Engineering
• Biomedical Engineering
• Materials Science

Background:

• Electrical impedance spectroscopy (EIS) systems are increasingly integrated into portable, wearable, and implantable devices for the Internet-of-Things (IoT) era.
• The performance of on-chip EIS systems is critically dependent on the integrated circuit (IC) responsible for impedance readout.
• Key performance metrics, including frequency range, power consumption, accuracy, detection range, and throughput, are significantly influenced by the readout IC design.

Approach:

• This review examines state-of-the-art impedance-readout ICs, focusing on techniques that enhance energy efficiency, frequency range, accuracy, dynamic range, low noise, and throughput.
• It discusses advancements addressing the trend towards miniaturization and convenience, including the use of two-electrode or dry electrode configurations instead of traditional four-electrode wet electrode systems.
• The review analyzes the principles, advantages, and disadvantages of various technologies developed to ensure reliable impedance measurements at challenging electrode interfaces.

Key Points:

• Achieving high energy efficiency is paramount for the widespread adoption of EIS in battery-powered portable and wearable applications.
• The shift to two-electrode and dry electrode configurations necessitates novel IC designs to maintain measurement accuracy and reliability.
• High input impedance is crucial for accurate measurements, especially when dealing with low-conductivity biological tissues or dry electrodes.

Conclusions:

• Advancements in impedance-readout ICs are crucial for the future development of sophisticated EIS systems for IoT and biomedical applications.
• Future research should focus on further improving energy efficiency, expanding the frequency range, and enhancing the robustness of readout ICs for diverse electrode interfaces.
• The integration of high-performance impedance-readout ICs will enable more accessible and powerful point-of-care diagnostics and health monitoring solutions.