Design of a Wearable Parallel Electrical Impedance Imaging System for Healthcare

TL;DR

This paper presents a portable, wireless EIT system using multiple AD5933 chips for real-time lung imaging, achieving high accuracy, synchronization, and low noise, suitable for healthcare applications.

Contribution

The novel parallel AD5933-based design enables high-speed, synchronized impedance imaging for real-time lung monitoring in a wearable system.

Findings

Signal-to-noise ratio > 50 dB

Relative standard deviation < 0.3%

Reciprocity error < 0.8%

Abstract

A wireless wearable Electrical Impedance Tomography (EIT) system has been developed utilizing the AD5933 chip to achieve real-time imaging of lung respiration. The system employs a voltage excitation method tailored to human impedance characteristics, injecting current by applying a known voltage and measuring the resulting current through the body. Additionally, specific measures have been implemented to effectively suppress signal oscillations and leakage currents caused by parasitic capacitances. To enhance data acquisition speed, the system employs five parallel AD5933 units, with multiple techniques implemented to ensure high synchronization during simultaneous measurements. Performance testing shows that the system achieves a signal-to-noise ratio greater than 50 dB, a relative standard deviation below 0.3%, and a reciprocity error under 0.8%. Imaging experiments using a water tank phantom, human lungs during breathing, and a resting human calf further demonstrate that this portable EIT system can accurately measure biological tissues with high precision and low cost.