Penetrating microelectrode arrays with low-impedance sputtered iridium oxide electrode coatings

Abstract

Sputtered iridium oxide (SIROF) is a candidate low-impedance coating for neural stimulation and recording electrodes. SIROF on planar substrates has exhibited a high charge-injection capacity and impedance suitable for indwelling cortical microelectrode applications. In the present work, the properties of SIROF electrode coatings deposited onto multi-shank penetrating arrays intended for intracortical and intraneural applications were examined. The charge-injection properties under constant current pulsing were evaluated for a range of pulsewidths and current densities using voltage transients to determine maximum potential excursions in an inorganic model of interstitial fluid at 37 degrees C. The charge-injection capacity of the SIROFs was significantly improved by the use of positive potential biasing in the interpulse period, but even without bias, the SIROFs reversibly inject higher charge than other iridium oxides or platinum. Typical deliverable charge levels of 25 to 160 nC/phase were obtained with 2000 mum(2) electrodes depending on pulsewidth and interpulse bias. Similar sized platinum electrodes could inject 3 to 8 nC/phase.

Neural Stimulation and Recording with Bidirectional, Soft Carbon Nanotube Fiber Microelectrodes

“…Finally, the mechanical mismatch between stiff metals and soft brain tissue causes inflammation and scarring, neuronal degeneration, and loss of recording functionality in chronic use. 10,11 Metallic and organic coatings on the electrode active site, such as poly(3,4ethylenedioxythiophene) (PEDOT) 12,13 and iridium oxide (IrOx), 14 have been shown to improve charge transfer and impedance properties. However, degradation and delamination of the coating materials still greatly limit electrode longevity and, thus, their chronic use.…”

“…Metallic and organic coatings on the electrode active site, such as poly(3,4-ethylenedioxythiophene) (PEDOT) , and iridium oxide (IrOx), have been shown to improve charge transfer and impedance properties. However, degradation and delamination of the coating materials still greatly limit electrode longevity and, thus, their chronic use. ,, Recently, carbon fibers have been used to fabricate subcellular scale size microelectrodes (4.5 to 7 μm in diameter) with improved performance in terms of biocompatibility and quality of chronic in vivo recordings. , However, the high impedance and low charge injection of carbon fibers make them unsuitable for chronic applications in neural stimulation.…”

Effects of central nervous system electrical stimulation on non-neuronal cells

“…It is beneficial for achieving dexterous prosthesis control for humans with sensorimotor dysfunction ( Fifer et al, 2020 ). ICMS employs microelectrodes with geometric surface areas typically less than 5,000 μm 2 ( Cogan et al, 2009 ; Wark et al, 2013 ; Pancrazio et al, 2017 ). The small electrode size enables high spatial selectivity which may allow for a wider range of stimulation parameters, evoking a wider range of perceived sensation in patients.…”

Electrochemically synthesized PANI-MnO_2 coatings and their effect on interface properties of neural microelectrode

“…The interface between neural microelectrodes and neural tissue plays a significant role in the longterm performance of these devices, which can ensure high quality record signal and effective charge conduction [5,6]. A certain charge density is required to generate neural activity during stimulation process using microelectrode arrays [7,8].…”