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Repeated voltage biasing improves unit recordings by reducing resistive tissue impedances
Matthew D Johnson1, Kevin J Otto, Daryl R Kipke
1Biomedical Engineering Department, University of Michigan, Ann Arbor, MI 48109, USA. mdjzz@umich.edu
Summary
Microelectrode "rejuvenation" using a brief voltage pulse improves long-term neural recording stability. This method reduces tissue encapsulation, enhancing signal quality and extending microelectrode functionality for chronic implants.
Area of Science:
- Neuroscience
- Biomedical Engineering
- Materials Science
Background:
- Chronic microelectrode implantation leads to tissue encapsulation, impairing neural recording.
- Reactive tissue growth around electrodes increases impedance and reduces signal-to-noise ratio (SNR).
Purpose of the Study:
- Investigate the duration and efficacy of a
- rejuvenation
- intervention for encapsulated microelectrode sites.
- Determine the impact of single and multiple voltage bias sessions on electrode performance.
Main Methods:
- Electrophysiological recordings to assess neural signals.
- Cyclic voltammetry and impedance spectroscopy for interface characterization.
- Equivalent circuit modeling to analyze electrode-tissue interface parameters.
Main Results:
- Rejuvenation improved SNR for 1-7 days, peaking within 24 hours.
- Reduced root-mean-square (RMS) noise and adsorbed tissue resistance (Ren) were observed.
- Longer-lasting SNR improvements correlated with reduced extracellular tissue resistance (Rex) and cellular membrane area (Am).
Conclusions:
- Rejuvenation effectively mitigates tissue encapsulation effects on microelectrodes.
- Repeated rejuvenation sessions can restore electrode performance to near-surgical levels.
- This intervention strategy shows promise for prolonging the functional lifetime of chronically implanted microelectrodes.