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Updated: Jun 1, 2026
09:36
In Situ Lithiated Reference Electrode: Four Electrode Design for In-operando Impedance Spectroscopy
Published on: September 12, 2018
Front end with offset-free symmetrical current source optimized for time domain impedance spectroscopy.
Uwe Pliquett1, Markus Schönfeldt, Andreas Barthel
1Institut für Bioprozess- und Analysenmesstechnik eV, Rosenhof D-37308 Heilbad Heiligenstadt, Germany. uwe.pliquett@iba-heiligenstadt.de
Physiological Measurement
|June 8, 2011
Summary
This study introduces an active front end for fast impedance measurements using a voltage-controlled current source. It minimizes electrode polarization and noise, achieving a wide bandwidth for accurate time-domain analysis.
Area of Science:
- Electrical Engineering
- Biomedical Engineering
- Instrumentation
Background:
- Fast impedance measurements often use broad bandwidth signals in the time domain.
- Minimizing harmonic distortion and compensating for electrode polarization and noise are critical challenges, especially at low frequencies.
Purpose of the Study:
- To develop an active front end for fast impedance measurements.
- To enable accurate measurements across a wide range of impedances by compensating for parasitic capacitances and circuit asymmetries.
Main Methods:
- Utilizing a voltage-controlled current source with feedback for parasitic capacitance compensation.
- Employing a current conveyor and voltage inverter for a symmetric, offset-free output.
- Implementing an independent feedback loop for offset compensation and ensuring current source stability with small electrodes.
Main Results:
- Achieved a bandwidth from DC to 20 MHz for impedance magnitudes below 5 kΩ.
- Demonstrated compensation for parasitic capacitances and circuit asymmetries.
- Ensured stability of the current source for measurements in aqueous solutions using small metal electrodes.
Conclusions:
- The developed active front end is suitable for fast time-domain impedance measurements.
- The design effectively minimizes noise and electrode polarization effects.
- The system provides accurate and stable measurements across a broad frequency range.
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