Excimer laser deinsulation of Parylene-C on iridium for use in an activated iridium oxide film-coated Utah electrode array

Yoo, Ji Hye; Negi, Sandeep; Tathireddy, Prashant; Solzbacher, Florian; Song, Jung‐Han; Rieth, Loren

doi:10.1016/j.jneumeth.2013.02.010

Cited by 18 publications

(12 citation statements)

References 30 publications

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“…Laser ablation has been used previously to selectively remove parylene-C from electrode tips of the UTAH (Blackrock Microsystems) neural recording array. [42] In that instance, the electrodes themselves remained intact following laser treatment. Using LCGO fibres as the electrode material, low laser powers (230-250 mW) cut through both the coating and the fibre.…”

Section: Electrode Fabricationmentioning

confidence: 97%

Soft, Flexible Freestanding Neural Stimulation and Recording Electrodes Fabricated from Reduced Graphene Oxide

Apollo

Maturana

Tong

et al. 2015

Adv Funct Materials

131

148

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. (2015). Soft, flexible freestanding neural stimulation and recording electrodes fabricated from reduced graphene oxide. Advanced Functional Materials, 25 (23), 3551-3559. Soft, flexible freestanding neural stimulation and recording electrodes fabricated from reduced graphene oxide AbstractThere is an urgent need for conductive neural interfacing materials that exhibit mechanically compliant properties, while also retaining high strength and durability under physiological conditions. Currently, implantable electrode systems designed to stimulate and record neural activity are composed of rigid materials such as crystalline silicon and noble metals. While these materials are strong and chemically stable, their intrinsic stiffness and density induce glial scarring and eventual loss of electrode function in vivo. Conductive composites, such as polymers and hydrogels, have excellent electrochemical and mechanical properties, but are electrodeposited onto rigid and dense metallic substrates. In the work described here, strong and conductive microfibers (40-50 μm diameter) wet-spun from liquid crystalline dispersions of graphene oxide are fabricated into freestanding neural stimulation electrodes. The fibers are insulated with parylene-C and laser-treated, forming "brush" electrodes with diameters over 3.5 times that of the fiber shank. The fabrication method is fast, repeatable, and scalable for high-density 3D array structures and does not require additional welding or attachment of larger electrodes to wires. The electrodes are characterized electrochemically and used to stimulate live retina in vitro. Additionally, the electrodes are coated in a water-soluble sugar microneedle for implantation into, and subsequent recording from, visual cortex. AbstractThere is an urgent need for conductive neural interfacing materials that exhibit mechanicallycompliant properties while also retaining high strength and durability in physiological conditions. Currently, implantable electrode systems designed to stimulate and record neural activity are comprised of rigid materials such as crystalline silicon and noble metals. While these materials are strong and chemically stable, their intrinsic stiffness and density induce glial scarring and eventual loss of electrode function in vivo. Conductive composites, such as polymers and hydrogels, have excellent electrochemical and mechanical properties, but are electrodeposited onto rigid and dense metallic substrates. In the work described here, strong and conductive microfibres (40-50 µm diameter) wet-spun from liquid crystalline dispersions of graphene oxide are fabricated into freestanding neural stimulation electrodes. The fibres were insulated with parylene-C and laser-treated, forming "brush" electrodes with diameters over 3.5 times that of the fibre shank. The fabrication method is fast, repeatable, and scalable for high density 3-D array structures and does not require additional welding or attachment of larger electrodes to wires. The electrodes are characterized electroch...

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Section: Electrode Fabricationmentioning

confidence: 97%

Soft, Flexible Freestanding Neural Stimulation and Recording Electrodes Fabricated from Reduced Graphene Oxide

Apollo

Maturana

Tong

et al. 2015

Adv Funct Materials

131

148

View full text Add to dashboard Cite

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“…Due to platinum and gold’s faradaic nature, their limitations of charge delivery capacity remain a great challenge, especially for the electrodes with small geometric surface areas. With weak or no faradaic reaction charge transduction, the contribution of double-layer capacitive coupling in charge delivery is often limited [ 83 ]. Thus, materials with higher electroactivity and ability to support reversible faradaic reactions are needed to promote the charge transfer in the electrode–tissue interface.…”

Section: Metals and Their Derivativesmentioning

confidence: 99%

Advanced Metallic and Polymeric Coatings for Neural Interfacing: Structures, Properties and Tissue Responses

et al. 2021

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Neural electrodes are essential for nerve signal recording, neurostimulation, neuroprosthetics and neuroregeneration, which are critical for the advancement of brain science and the establishment of the next-generation brain–electronic interface, central nerve system therapeutics and artificial intelligence. However, the existing neural electrodes suffer from drawbacks such as foreign body responses, low sensitivity and limited functionalities. In order to overcome the drawbacks, efforts have been made to create new constructions and configurations of neural electrodes from soft materials, but it is also more practical and economic to improve the functionalities of the existing neural electrodes via surface coatings. In this article, recently reported surface coatings for neural electrodes are carefully categorized and analyzed. The coatings are classified into different categories based on their chemical compositions, i.e., metals, metal oxides, carbons, conducting polymers and hydrogels. The characteristic microstructures, electrochemical properties and fabrication methods of the coatings are comprehensively presented, and their structure–property correlations are discussed. Special focus is given to the biocompatibilities of the coatings, including their foreign-body response, cell affinity, and long-term stability during implantation. This review article can provide useful and sophisticated insights into the functional design, material selection and structural configuration for the next-generation multifunctional coatings of neural electrodes.

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“…Carbon nanomaterials achieve this mainly by increasing the electrochemical surface area (ESA), whereas PEDOT–PSS and IrO x introduce a dominant faradaic charge transfer mechanism. However, premature delamination and cracking during prolonged studies as well as large variability between samples has been reported repeatedly in the literature. , A widely accepted electrode material for chronic recording and stimulation applications in implantable devices is iridium oxide films: either sputtered iridium oxide films (SIROF) or activated iridium oxide films (AIROF). − Cogan et al have studied the properties of AIROF and SIROF in detail by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). AIROF electrodes are fabricated on iridium metal by cyclic oxidation and reduction of the metal surface after the electrode array has been fabricated.…”

Section: Introductionmentioning

confidence: 99%

Integration of High-Charge-Injection-Capacity Electrodes onto Polymer Softening Neural Interfaces

Arreaga-Salas

Avendano-Bolivar

Simon

et al. 2015

ACS Appl. Mater. Interfaces

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Softening neural interfaces are implanted stiff to enable precise insertion, and they soften in physiological conditions to minimize modulus mismatch with tissue. In this work, a high-charge-injection-capacity iridium electrode fabrication process is detailed. For the first time, this process enables integration of iridium electrodes onto softening substrates using photolithography to define all features in the device. Importantly, no electroplated layers are utilized, leading to a highly scalable method for consistent device fabrication. The iridium electrode is metallically bonded to the gold conductor layer, which is covalently bonded to the softening substrate via sulfur-based click chemistry. The resulting shape-memory polymer neural interfaces can deliver more than 2 billion symmetric biphasic pulses (100 μs/phase), with a charge of 200 μC/cm(2) and geometric surface area (GSA) of 300 μm(2). A transfer-by-polymerization method is used in combination with standard semiconductor processing techniques to fabricate functional neural probes onto a thiol-ene-based, thin film substrate. Electrical stability is tested under simulated physiological conditions in an accelerated electrical aging paradigm with periodic measurement of electrochemical impedance spectra (EIS) and charge storage capacity (CSC) at various intervals. Electrochemical characterization and both optical and scanning electron microscopy suggest significant breakdown of the 600 nm-thick parylene-C insulation, although no delamination of the conductors or of the final electrode interface was observed. Minor cracking at the edges of the thin film iridium electrodes was occasionally observed. The resulting devices will provide electrical recording and stimulation of the nervous system to better understand neural wiring and timing, to target treatments for debilitating diseases, and to give neuroscientists spatially selective and specific tools to interact with the body. This approach has uses for cochlear implants, nerve cuff electrodes, penetrating cortical probes, spinal stimulators, blanket electrodes for the gut, stomach, and visceral organs and a host of other custom nerve-interfacing devices.

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Excimer laser deinsulation of Parylene-C on iridium for use in an activated iridium oxide film-coated Utah electrode array

Cited by 18 publications

References 30 publications

Soft, Flexible Freestanding Neural Stimulation and Recording Electrodes Fabricated from Reduced Graphene Oxide

Soft, Flexible Freestanding Neural Stimulation and Recording Electrodes Fabricated from Reduced Graphene Oxide

Advanced Metallic and Polymeric Coatings for Neural Interfacing: Structures, Properties and Tissue Responses

Integration of High-Charge-Injection-Capacity Electrodes onto Polymer Softening Neural Interfaces

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