Laser patterning of platinum electrodes for safe neurostimulation

Green, Rylie A.; Matteucci, P; Dodds, C.; Palmer, Jonathan; Dueck, Wolfram F.; Hassarati, Rachelle T.; Byrnes-Preston, Philip; Lovell, Nigel H.; Suaning, Gregg J.

doi:10.1088/1741-2560/11/5/056017

Cited by 58 publications

(74 citation statements)

References 51 publications

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“…For the 0.06 cm 2 Medtronic 3387 or 3389 electrode , 30 µC/cm 2 corresponds to k of 1.73. For the St. Jude Brio system electrode , 30 µC/cm 2 corresponds to k of 1.77 if the electrode area is 0.065 cm 2 with the latter number being more likely to be used clinically. For the Neuropace RNS system , with electrode area of 0.08 cm 2 the software prevents programming above 25 µC/cm 2 , which corresponds to k of 1.69.…”

Section: Discussionmentioning

confidence: 99%

“…This approach is based on studies by McCreery et al performed in acute stimulation experiments in feline cortex (9,10) at a fixed frequency of 50 Hz and fixed biphasic 0.4 millisecond pulses. This model developed by Shannon (8) has become very popular among scholars (5,6,(11)(12)(13)(14)(15)(16). However, since the inception of the Shannon model, medical device manufacturers have performed a substantial number of studies to assess the safety of electrical stimulation in a number of animal models (pig, sheep, monkey, dog, goat); in different anatomical locations (deep brain structures, spinal cord, vagus nerve and other peripheral nerves); stimulation duration (several hours to years of chronic stimulation) with a range of frequencies (from 10 to 10,000 Hz); and a variety of pulse shapes and stimulation amplitudes.…”

Section: Introductionmentioning

confidence: 99%

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Public Regulatory Databases as a Source of Insight for Neuromodulation Devices Stimulation Parameters

Kumsa

Steinke

Molnar

et al. 2018

Neuromodulation: Technology at the Neural Interface

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Objective The Shannon model is often used to define an expected boundary between non-damaging and damaging modes of electrical neurostimulation. Numerous preclinical studies have been performed by manufacturers of neuromodulation devices using different animal models and a broad range of stimulation parameters while developing devices for clinical use. These studies are mostly absent from peer-reviewed literature, which may lead to this information being overlooked by the scientific community. We aimed to locate summaries of these studies accessible via public regulatory databases and to add them to a body of knowledge available to a broad scientific community. Methods We employed web search terms describing device type, intended use, neural target, therapeutic application, company name, and submission number to identify summaries for premarket approval (PMA) devices and 510(k) devices. We filtered these records to a subset of entries that have sufficient technical information relevant to safety of neurostimulation. Results We identified 13 product codes for 8 types of neuromodulation devices. These led us to devices that have 22 PMAs and 154 510(k)s and six transcripts of public panel meetings. We found one PMA for a brain, peripheral nerve, and spinal cord stimulator and five 510(k) spinal cord stimulators with enough information to plot in Shannon coordinates of charge and charge density per phase. Conclusions Analysis of relevant entries from public regulatory databases reveals use of pig, sheep, monkey, dog, and goat animal models with deep brain, peripheral nerve, muscle and spinal cord electrode placement with a variety of stimulation durations (hours to years); frequencies (10–10,000 Hz) and magnitudes (Shannon k from below zero to 4.47). Data from located entries indicate that a feline cortical model that employs acute stimulation might have limitations for assessing tissue damage in diverse anatomical locations, particularly for peripheral nerve and spinal cord simulation.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Public Regulatory Databases as a Source of Insight for Neuromodulation Devices Stimulation Parameters

Kumsa

Steinke

Molnar

et al. 2018

Neuromodulation: Technology at the Neural Interface

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“…Thereby a distinction between surface and bulk processes can be made. In the latter, the metallization of an electrode (bulk material) is selectively removed by laser roughening or metal etching, yielding an enlarged active surface area and respectively lower impedance compared to untreated surfaces of equal dimensions [11][12][13]. The surface modification in contrast relies on the additional deposition of either a material that provides a highly roughened surface (topographical approach) or a material that features additional electrochemical means to improve the impedance and charge delivery capacity (chemical approach).…”

Section: Introductionmentioning

confidence: 99%

Nanostructured platinum grass enables superior impedance reduction for neural microelectrodes

2015

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Micro-sized electrodes are essential for highly sensitive communication at the neural interface with superior spatial resolution. However, such small electrodes inevitably suffer from high electrical impedance and thus high levels of thermal noise deteriorating the signal to noise ratio. In order to overcome this problem, a nanostructured Pt-coating was introduced as add-on functionalization for impedance reduction of small electrodes. In comparison to platinum black deposition, all used chemicals in the deposition process are free from cytotoxic components. The grass-like nanostructure was found to reduce the impedance by almost two orders of magnitude compared to untreated samples which was lower than what could be achieved with conventional electrode coatings like IrOx or PEDOT. The realization of the Pt-grass coating is performed via a simple electrochemical process which can be applied to virtually any possible electrode type and accordingly shows potential as a universal impedance reduction strategy. Elution tests revealed non-toxicity of the Pt-grass and the coating was found to exhibit strong adhesion to the metallized substrate.

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“…For reference, charge injection limits for carbon nanotube array electrodes, 36 titanium nitride electrodes 37 and thick Pt roughened with a 250x area increase were extracted from literature and added to Figure 4b. Roughened thin-films have greater charge injection limits than laser roughened Pt foil electrodes (∼0.2 mC/cm 2 for pulse widths 0.8-1 ms), 9 comparable charge injection limits to TiN 37 ( Figure 4b) and limits just below carbon nanotubebased material (Figure 4b). 36 Surprisingly, despite the lower achieved roughness, thin-film Pt roughened with a 44x area increase had greater charge injection limits than the thick Pt roughened with 250x area increase for pulse widths below 0.3 ms.…”

Section: Resultsmentioning

confidence: 98%

Electrochemical Roughening of Thin-Film Platinum for Neural Probe Arrays and Biosensing Applications

Ivanovskaya

Belle

Yorita

et al. 2018

J. Electrochem. Soc.

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We report a method for electrochemical roughening of thin-film platinum (Pt) electrodes that increases active surface area, decreases electrode impedance, increases charge injection capacity, increases sensitivity of biosensors and improves adhesion of electrochemically deposited films. First, a well-established technique for electrochemical roughening of thick Pt electrodes (wires and foils) by oxidation-reduction pulses was modified for use on thin-film Pt. Optimal roughening of thin-film Pt electrodes with this established protocol in a sulfuric acid solution was found to occur at about four times lower frequency than that typically used for thick Pt. This modification in established procedure created a 21x surface area increase but showed nanoscale cracks from inter-grain Pt dissolution that compromised film integrity. A crack free surface with Pt nanocrystal re-deposition (20-30 nm in size) and higher enhancement in surface area (44x) was obtained when the electrolyte was switched to a non-adsorbing perchloric acid solution. These electrochemically roughened electrodes have charge injection limits comparable to titanium nitride and just below carbon nanotube-based materials. Roughened microelectrodes showed a 2.8x increase in sensitivity to hydrogen peroxide detection, indicative of improved enzymatic biosensor performance. Platinum iridium and iridium oxide coatings on these roughened surfaces showed an improvement in adhesion. Microfabrication techniques have enabled the bulk fabrication of robust, reproducible neural interfaces. 1,2 These neural interfaces typically contain conductive metal electrodes that serve as the 'interface' between the device and the tissue. 3 When microfabricated, these electrodes are typically thin films of metal, a few hundred nanometers thick and recent advances show these interfaces to be constructed on thin flexible substrates, further improving the ability of electrodes to interface with tissue. 4-7 While these thin film electrodes generally act very similar to bulk metal found in non-microfabricated neural interfaces, they can be more delicate than bulk metal, 8 especially when fabricated on a flexible substrate. Both bulk and thin film metal interfaces demand highest performance to ensure that they can properly interface with tissue without causing damage to the tissue. Often, electrode surface modifications are needed to enhance performance.Enhanced electrode performance can be accomplished by 1) roughening the electrode surface to increase the effective surface area; 9-11 or, 2) depositing a thin-film coating of a material with enhanced electrochemical activity. [12][13][14][15] When depositing a different thin film electroactive material over the electrode to improve performance, there is often poor adhesion of the deposited film to the electrode surface. 9,16 Poor film adhesion compromises the mechanical robustness of an implantable device which may result in immediate delamination or decreased lifetime of the electrode upon implantation, ultimately deteriorating sens...

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Laser patterning of platinum electrodes for safe neurostimulation

Cited by 58 publications

References 51 publications

Public Regulatory Databases as a Source of Insight for Neuromodulation Devices Stimulation Parameters

Public Regulatory Databases as a Source of Insight for Neuromodulation Devices Stimulation Parameters

Nanostructured platinum grass enables superior impedance reduction for neural microelectrodes

Electrochemical Roughening of Thin-Film Platinum for Neural Probe Arrays and Biosensing Applications

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