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Mousavi H, Dauly G, Dieuset G, El Merhie A, Ismailova E, Wendling F, Al Harrach M. Tuning Microelectrodes' Impedance to Improve Fast Ripples Recording. Bioengineering (Basel) 2024; 11:102. [PMID: 38275582 PMCID: PMC11154299 DOI: 10.3390/bioengineering11010102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Revised: 01/11/2024] [Accepted: 01/19/2024] [Indexed: 01/27/2024] Open
Abstract
Epilepsy is a chronic neurological disorder characterized by recurrent seizures resulting from abnormal neuronal hyperexcitability. In the case of pharmacoresistant epilepsy requiring resection surgery, the identification of the Epileptogenic Zone (EZ) is critical. Fast Ripples (FRs; 200-600 Hz) are one of the promising biomarkers that can aid in EZ delineation. However, recording FRs requires physically small electrodes. These microelectrodes suffer from high impedance, which significantly impacts FRs' observability and detection. In this study, we investigated the potential of a conductive polymer coating to enhance FR observability. We employed biophysical modeling to compare two types of microelectrodes: Gold (Au) and Au coated with the conductive polymer poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) (Au/PEDOT:PSS). These electrodes were then implanted into the CA1 hippocampal neural network of epileptic mice to record FRs during epileptogenesis. The results showed that the polymer-coated electrodes had a two-order lower impedance as well as a higher transfer function amplitude and cut-off frequency. Consequently, FRs recorded with the PEDOT:PSS-coated microelectrode yielded significantly higher signal energy compared to the uncoated one. The PEDOT:PSS coating improved the observability of the recorded FRs and thus their detection. This work paves the way for the development of signal-specific microelectrode designs that allow for better targeting of pathological biomarkers.
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Affiliation(s)
- Hajar Mousavi
- Bioelectronics Department, Ecoles des Mines de Saint Etienne, CMP-EMSE, MOC, 13541 Gardanne, France; (H.M.); (A.E.M.); (E.I.)
| | - Gautier Dauly
- INSERM, LTSI-U1099, University of Rennes, 35000 Rennes, France; (G.D.); (G.D.); (F.W.)
| | - Gabriel Dieuset
- INSERM, LTSI-U1099, University of Rennes, 35000 Rennes, France; (G.D.); (G.D.); (F.W.)
| | - Amira El Merhie
- Bioelectronics Department, Ecoles des Mines de Saint Etienne, CMP-EMSE, MOC, 13541 Gardanne, France; (H.M.); (A.E.M.); (E.I.)
- Laboratoire Matière et Systèmes Complexes, Université Paris Cité, CNRS UMR 7057, 10 Rue Alice Domon et Léonie Duquet, 75013 Paris, France
| | - Esma Ismailova
- Bioelectronics Department, Ecoles des Mines de Saint Etienne, CMP-EMSE, MOC, 13541 Gardanne, France; (H.M.); (A.E.M.); (E.I.)
| | - Fabrice Wendling
- INSERM, LTSI-U1099, University of Rennes, 35000 Rennes, France; (G.D.); (G.D.); (F.W.)
| | - Mariam Al Harrach
- INSERM, LTSI-U1099, University of Rennes, 35000 Rennes, France; (G.D.); (G.D.); (F.W.)
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