Electrochemical Roughening of Thin-Film Platinum Macro and Microelectrodes

Ivanovskaya, Anna; Belle, Anna M.; Yorita, Allison; Qian, Fang; Chen, Supin; Tooker, Angela; Lozada, R.; Dahlquist, Dylan; Tolosa, Vanessa

doi:10.3791/59553

Cited by 2 publications

(3 citation statements)

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“…To maintain sufficient SNR and increase electrode charge storage capacity and charge injection efficiency for stimulation, deposition parameters for the PtIr metal electrode were optimized to provide low impedance, high charge-storage capacitance and high doublelayer capacitance without requiring post-fabrication surface modifications. Untreated thin-film Pt is reported to have a double-layer capacitance (Q) of 0.01-0.06 mF cm −2 [25,34] while post-processed surface roughening of thin-film Pt contacts achieved a Q of 2 mF cm −2 , or approximately 40 times higher than that of untreated Pt film [25]. The co-sputter process developed here (60% Pt and 40% Ir) resulted in a measured Q of approximately 3.1 mF cm −2 , at least 50 times increase without post-processing when fit with the same model.…”

Section: Array Fabricationmentioning

confidence: 99%

“…However, PEDOT:PSS coatings can suffer from cracks and delaminate from their metallic substrates during prolonged periods of charge-balanced biphasic electrical stimulation [23]. Additional manufacturing processes (such as surface roughening) improve coating lifetime [22,24,25] and work is continuing to improve the lifetime of PEDOT:PSS. However, with an eye towards rapid translation to clinical and research use, we sought to use alternative materials, such as co-deposited platinum-iridium which does not require additional surface processing and still provides lower impedance and higher charge-transfer capacity properties compared to an untreated platinum surface.…”

Section: Introductionmentioning

confidence: 99%

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Thin-film microfabrication and intraoperative testing of µECoG and iEEG depth arrays for sense and stimulation

et al. 2021

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Objective. Intracranial neural recordings and electrical stimulation are tools used in an increasing range of applications, including intraoperative clinical mapping and monitoring, therapeutic neuromodulation, and brain computer interface control and feedback. However, many of these applications suffer from a lack of spatial specificity and localization, both in terms of sensed neural signal and applied stimulation. This stems from limited manufacturing processes of commercial-off-the-shelf (COTS) arrays unable to accommodate increased channel density, higher channel count, and smaller contact size. Approach. Here, we describe a manufacturing and assembly approach using thin-film microfabrication for 32-channel high density subdural micro-electrocorticography (µECoG) surface arrays (contacts 1.2 mm diameter, 2 mm pitch) and intracranial electroencephalography (iEEG) depth arrays (contacts 0.5 mm × 1.5 mm, pitch 0.8 mm × 2.5 mm). Crucially, we tackle the translational hurdle and test these arrays during intraoperative studies conducted in four humans under regulatory approval. Main results. We demonstrate that the higher-density contacts provide additional unique information across the recording span compared to the density of COTS arrays which typically have electrode pitch of 8 mm or greater; 4 mm in case of specially ordered arrays. Our intracranial stimulation study results reveal that refined spatial targeting of stimulation elicits evoked potentials with differing spatial spread. Significance. Thin-film, μECoG and iEEG depth arrays offer a promising substrate for advancing a number of clinical and research applications reliant on high-resolution neural sensing and intracranial stimulation.

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Section: Array Fabricationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Thin-film microfabrication and intraoperative testing of µECoG and iEEG depth arrays for sense and stimulation

et al. 2021

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“…Increasing the electrochemical capacitance of metal electrodes is typically accomplished either by roughening the electrode surface [17] or adding a coating. A variety of materials that fulfill this role have risen to the fore including iridium oxide, platinum black, titanium nitride, hydrogels [18] and a range of exotic conducting polymers [19].…”

Section: Introductionmentioning

confidence: 99%

Electrically conducting diamond films grown on platinum foil for neural stimulation

et al. 2019

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Objective. With the strong drive towards miniaturization of active implantable medical devices and the need to improve the resolution of neural stimulation arrays, there is keen interest in the manufacture of small electrodes capable of safe, continuous stimulation. Traditional materials such as platinum do not possess the necessary electrochemical properties to stimulate neurons safely when electrodes are very small (i.e. typically less than about 300 µm (78 400 µm2)). While there are several commercially viable alternative electrode materials such as titanium nitride and iridium oxide, an attractive approach is modification of existing Pt arrays via a high electrochemical capacitance material coating. Such a composite electrode could still take advantage of the wide range of fabrication techniques used to make platinum-based devices. The coating, however, must be biocompatible, exhibit good adhesion and ideally be long lasting when implanted in the body. Approach. Platinum foils were roughened to various degrees with regular arrays of laser milled pits. Conducting diamond films were grown on the foils by microwave plasma chemical vapor deposition. The adhesion strength of the films to the platinum was assessed by prolonged sonication and accelerated aging. Electrochemical properties were evaluated and compared to previous work. Main results. In line with previous results, diamond coatings increased the charge injection capacity of the platinum foil by more than 300% after functionalization within an oxygen plasma. Roughening of the underlying platinum substrate by laser milling was required to generate strong adhesion between the diamond and the Pt foil. Electrical stress testing, near the limits of safe operation, showed that the diamond films were more electrochemically stable than platinum controls. Significance. The article describes a new method to protect platinum electrodes from degradation in vivo. A 300% increase in charge injection means that device designers can safely employ diamond coated platinum stimulation electrodes at much smaller sizes and greater density than is possible for platinum.

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Electrochemical Roughening of Thin-Film Platinum Macro and Microelectrodes

Cited by 2 publications

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Thin-film microfabrication and intraoperative testing of µECoG and iEEG depth arrays for sense and stimulation

Thin-film microfabrication and intraoperative testing of µECoG and iEEG depth arrays for sense and stimulation

Electrically conducting diamond films grown on platinum foil for neural stimulation

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