PA/MA - Design and Implementation of an active electrode for EIT measurements

Entwurf und Implementierung einer aktiven Elektrode für EIT Messungen

Design and Implementation of an active electrode for EIT measurements

Motivation and Objective

Electrical Impedance Tomography (EIT) is an imaging technique used for process monitoring by reconstructing conductivity distributions within a medium. Traditional EIT systems use passive electrodes, which can suffer from signal degradation due to cable transmission losses and external noise. To improve signal quality and robustness, this thesis aims to design and implement an active electrode system.

The goal of this thesis is to develop small, active printed circuit boards (PCBs) that are placed directly at each electrode. These PCBs will include a current source for excitation and a single-ended to differential amplifier circuit, enabling differential signal transmission to the main measurement electronics. The key challenges involve circuit design, PCB layout, noise minimization, and optimizing the signal-to-noise ratio (SNR) over cable transmission.

System Requirements

• Excitation (and measurement) frequency range: 1 kHz to 100 kHz.

• Voltage amplitudes: from millivolts to several volts.

• Excitation current range: 10 µA to 10 mA.

• Signals may contain DC offsets, which should be removed (e.g., using a high-pass filter).

• Differential signal transmission to minimize noise and improve SNR.

Scope of Work

1. Literature Research

• Review state-of-the-art active electrode designs in EIT and related fields.

• Study noise sources and mitigation techniques in industrial process monitoring.

• Evaluate different current source designs for EIT excitation.

• Investigate signal transmission methods and differential amplification strategies.

2. Concept Development

• Define system requirements and design specifications.

• Develop block diagrams and functional descriptions of the active electrode system.

• Choose suitable electronic components based on performance criteria.

• Identify a suitable cable interface for robust signal transmission.

3. Circuit Design and PCB Layout

• Design the current source for controlled excitation.

• Develop a single-ended to differential amplifier for noise-resistant signal transmission.

• Implement a high-pass filter to remove DC offsets from the signal.

• Optimize power supply requirements and grounding strategies.

• Design the PCB layout with a focus on minimizing electromagnetic interference (EMI) and ensuring signal integrity.

4. Electrode Interface and Connectivity

• Develop a mechanical and electrical interface between the active electrodes and the main measurement unit.

• Design a suitable cable connection for reliable differential signal transmission.

• Implement shielding and grounding strategies to minimize noise pickup.

5. Implementation and Prototyping

• Manufacture and assemble the designed PCBs.

• Validate circuit performance through bench testing.

• Optimize power consumption and thermal management.

6. Measurements and Evaluation

• Characterize the electrical performance of the active electrodes.

• Assess the noise performance and compare with traditional passive electrode setups.

• Measure and optimize the SNR over cable transmission.

• Evaluate the effectiveness of the active electrode system in an EIT-based process monitoring setup.

Zeitplanung:

Checklist

• Introduction / tour in M4

• Urheberrechtsvereinbarung signed: https://www.tuhh.de/t3resources/sls/pdf/ZPA/Formulare_oeffentlich/Rechte_an_Abschlussarbeiten.pdf

• if applicable: signed confidential agreement

• official registration

Helpful links:

• Thesis Work / Studentische Arbeiten 

• Criteria for the evaluation of Bachelor's and Master's theses, handout version

• Laborordnung

• Spotlights / Kurzvorträge

• Templates (Latex, ppt etc.)

Document Upload Final Thesis / Dokumentenabgabe Abschlussdokument

File of final presentation / Dokumentenabgabe Abschlusspräsentation

Link for further files / Link für weitere Dokumente