PA - Design and Implementation of an EIT Electrode Placement Test Stand

Design und Aufbau eines Teststandes zur Elektrodenplatzierung für Elektrische Impedanztomographie

Introduction

Electrical Impedance Tomography (EIT) is a powerful imaging technique used in medical, industrial, and geophysical applications to reconstruct the conductivity distribution of a domain based on surface or internal electrode measurements. The quality of EIT reconstructions is highly dependent on the placement of electrodes, as it influences measurement sensitivity and image resolution.

This project aims to design and implement a modular test stand that allows for flexible electrode positioning within a controlled experimental setup. The test stand will enable systematic evaluation of different electrode configurations by allowing the user to place up to 32 electrodes at arbitrary locations within the domain. A current will be driven through two selected electrodes simultaneously while voltage measurements are taken from the remaining electrodes.

The test stand will serve as an experimental platform for studying optimal electrode placement strategies and validating numerical optimization methods, for improving EIT reconstruction accuracy.

Objectives

The primary objectives of this project are:

1. Design and fabricate a modular test stand that accommodates 32 electrodes and allows for flexible placement within a defined domain

2. Develop an electrode switching system that enables current injection through two electrodes at a time while collecting voltage measurements from the remaining electrodes.

3. Implement a control and data acquisition system to manage electrode switching and record measurement data.

4. Conduct experimental studies to compare different electrode configurations and evaluate their impact on EIT reconstructions.

5. Validate the test stand using numerical simulations and experimental data, demonstrating its effectiveness in optimizing electrode placement strategies.

Methodology

Test Stand Design

• Construct a physical setup using a non-conductive base (e.g., acrylic or 3D-printed material) where electrodes can be repositioned.

• Design modular electrode mounts to allow placement adjustments.

Electrode System

• Use 32 electrodes with secure connectors for stable contact.

• Implement a switching mechanism to dynamically select the two current-injecting electrodes and measuring electrode pairs

Current Injection and Measurement

• Use two current sources to parallelly inject predefined AC signals through a selected electrode triple.

• Measure voltage differences between non-current-carrying electrodes

Software and Data Processing

• Develop an interface for controlling the test stand, switching electrodes, and collecting data.

• Implement EIT reconstruction algorithms using existing libraries (e.g., EIDORS in MATLAB)

Experimental Validation

• Test different electrode placement strategies and compare reconstruction results.

• Evaluate the effectiveness of sensitivity-based electrode optimization by running experiments with and without optimized configurations.

• Analyze the effect of noise and environmental factors on measurement accuracy.

Expected Outcomes

1. A functional, modular EIT test stand allowing for flexible electrode placement.

2. A fully automated system for current injection, voltage measurement, and data acquisition.

3. Experimental validation of optimal electrode placement strategies based on sensitivity analysis.

4. A comparative study of different electrode configurations, demonstrating their impact on reconstruction accuracy.

5. A technical report and documentation detailing the system’s design, implementation, and results.

8. Conclusion

This project will provide hands-on experience in EIT hardware development and signal processing. The designed test stand will be a valuable tool for studying electrode placement strategies and improving EIT imaging accuracy.