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Active current electrodes for in vivo electrical impedance tomography
J Jossinet1, C Tourtel, R Jarry
1Institut National de la Santé et de la Recherche Médicale INSERM U281, Lyon, France.
Physiological Measurement
|May 1, 1994
Summary
This study presents active current electrodes for precise electrical impedance tomography measurements. These broad-band electrodes improve accuracy at high frequencies, enabling better tissue characterization.
Area of Science:
- Biomedical Engineering
- Electrical Engineering
- Medical Imaging
Background:
- Accurate impedance measurements are crucial for electrical impedance tomography (EIT).
- High frequencies are often required for effective tissue characterization using EIT.
- Existing electrode designs can be limited by lead capacitances at higher frequencies.
Purpose of the Study:
- To design and fabricate broad-band, active current electrodes for in vivo EIT measurements.
- To overcome limitations of lead capacitances in sourcing electrodes.
- To develop a method for creating reliable current sources for EIT applications.
Main Methods:
- Active current electrodes were designed and fabricated to eliminate lead capacitances.
- Resistor values were computed using a protocol considering application constraints and component availability.
- Component selection was optimized to minimize variability in circuit performance.
Main Results:
- The designed active electrodes are usable at frequencies exceeding 1 MHz.
- They support differential load impedances up to 2000 omega.
- The parallel output conductance is 0.85 microS +/- 2% for each electrode.
Conclusions:
- The developed design method enables the creation of broad-band active current electrodes for EIT.
- These electrodes are suitable for in vivo measurements at high frequencies.
- The design is adaptable for various applications and electrode configurations.