Changes in biphasic electrode impedance with protein adsorption and cell growth

Newbold, Carrie; Richardson, Rachael T.; Millard, Rodney; Huang, Christie Q; Milojevic, Dusan; Shepherd, Robert K.; Cowan, Robert

doi:10.1088/1741-2560/7/5/056011

Cited by 60 publications

(76 citation statements)

References 36 publications

(78 reference statements)

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“…Also, unspecific fibrous tissue formation around the electrode increases the transitory resistance and interferes with an optimal nerve-electrode interaction. 10,11 Therefore, inhibition of connective tissue growth and minimizing of the distance between neuronal cells and electrode are major goals in auditory implant related research. Surface properties influence the implant-tissue interactions.…”

Section: Introductionmentioning

confidence: 99%

Directing neuronal cell growth on implant material surfaces by microstructuring

et al. 2012

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CitationDirecting neuronal cell growth on implant material surfaces by microstructuring. 2012, 100 (4) Abstract: For best hearing sensation, electrodes of auditory prosthesis must have an optimal electrical contact to the respective neuronal cells. To improve the electrode-nerve interface, microstructuring of implant surfaces could guide neuronal cells toward the electrode contact. To this end, femtosecond laser ablation was used to generate linear microgrooves on the two currently relevant cochlear implant materials, silicone elastomer and platinum. Silicone surfaces were structured by two different methods, either directly, by laser ablation or indirectly, by imprinting using laser-microstructured molds. The influence of surface structuring on neurite outgrowth was investigated utilizing a neuronal-like cell line and primary auditory neurons. The pheochromocytoma cell line PC-12 and primary spiral ganglion cells were cultured on microstructured auditory implant materials. The orientation of neurite outgrowth relative to the microgrooves was determined. Both cell types showed a preferred orientation in parallel to the microstructures on both, platinum and on molded silicone elastomer. Interestingly, microstructures generated by direct laser ablation of silicone did not influence the orientation of either cell type. This shows that differences in the manufacturing procedures can affect the ability of microstructured implant surfaces to guide the growth of neurites. This is of particular importance for clinical applications, since the molding technique represents a reproducible, economic, and commercially feasible manufacturing procedure for the microstructured silicone surfaces of medical implants. V C 2012 Wiley Periodicals, Inc.J Biomed Mater Res Part B: Appl Biomater 00B: 000-000, 2012.

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Section: Introductionmentioning

confidence: 99%

Directing neuronal cell growth on implant material surfaces by microstructuring

et al. 2012

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“…Conversely, despite the growth of tissue around and at a distance from the electrode, the far-field effects measured with access resistance are less affected by electrical stimulation. Previous work with an in vitro model of this system also showed an increase in impedance with cell growth and a reduction with stimulation of cell-covered electrodes [Newbold et al, 2010[Newbold et al, , 2011. The assessment of living cells during stimulation indicated that electropermeabilization of the cell membranes may have occurred [Newbold et al, 2011].…”

Section: Introductionmentioning

confidence: 75%

Electropermeabilization of Adherent Cells with Cochlear Implant Electrical Stimulation in vitro

Newbold¹,

Farrington²,

Peters

et al. 2014

Audiol Neurotol

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Cochlear implant stimulation creates a reduction in electrode impedance that returns to pre-stimulation levels following cessation of stimulation and is presumed to be associated with the fibrous tissue covering over the electrode array. This study assessed the possibility that transitory impedance reduction originates from a change in the membrane permeability of cells on the electrode (electropermeabilization). These changes can be recorded using the dye propidium iodide, which fluoresces upon entry into the leaky cell. The in vitro model used showed impedance reduction and dye uptake into adherent cells overlying planar gold electrodes stimulated with as little as 5 min of clinically relevant cochlear implant stimulation. The delayed additions of propidium iodide showed a similar dye uptake to those groups with concurrent dye addition, suggesting the electropermeabilization was not reversible. Further understanding of the mechanisms behind these impedance and cell permeability changes with cochlear implant electrical stimulation may provide opportunities for creating long-lasting reductions in electrode impedance.

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“…This has been studied before both in vivo and in vitro, (14,15) but not at such a high temporal resolution for extended periods of time in a preclinical model. This could potentially lead to improved outcomes for patients as knowledge of temporal changes in the electrodetissue interface and associated safety limitations improves.…”

Section: Discussionmentioning

confidence: 99%

A Flexible Wireless System for Preclinical Evaluation of Retinal Prosthesis

Thien¹,

Millard²,

Epp³

et al. 2018

Sensors and Materials

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In this paper, we present a novel stimulation controller and monitoring system for evaluating the safety and efficacy of implantable neuroprosthetic devices in a preclinical setting. It features a programmable controller designed to be worn in a custom backpack by freely moving feline subjects. A custom controller powered two, modified, 22-channel clinical stimulators simultaneously. The controller and stimulators together weighed 140 g and measured 85 × 70 × 35 mm 3 . Power was supplied from a 3350 mAh lithium-ion battery. A Bluetooth-enabled laptop-PC base station managed up to six systems and allowed the remote adjustment of the stimulation amplitude and automated collection of stimulator telemetry data. The initial application was for the chronic safety testing of a 44-channel retinal prosthesis. Thirteen feline subjects were implanted with a suprachoroidal electrode array, which was then stimulated or monitored continuously for an average of 54.5 d. Batteries were changed twice weekly and electrode impedances were recorded hourly. This allowed broken electrodes and other issues to be quickly identified and addressed. The ability to remotely control the stimulation amplitude minimised the amount of subject handling that was required, likely reducing subject stress. Existing preclinical evaluation systems are either designed for short-term experiments and have many features but limited battery life, or for long-term static stimulation and are long-lived, but with restricted stimulation parameters and channel counts. Here, we have described a system designed to improve the chronic safety testing of electrode arrays. While it was used here with a suprachoroidal retinal implant, it could be readily adapted for other preclinical models requiring continuous, deterministic stimulation over a prolonged period.

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Changes in biphasic electrode impedance with protein adsorption and cell growth

Cited by 60 publications

References 36 publications

Directing neuronal cell growth on implant material surfaces by microstructuring

Directing neuronal cell growth on implant material surfaces by microstructuring

Electropermeabilization of Adherent Cells with Cochlear Implant Electrical Stimulation in vitro

A Flexible Wireless System for Preclinical Evaluation of Retinal Prosthesis

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