Excimer-laser deinsulation of Parylene-C coated Utah electrode array tips

Yoo, Ji Hye; Sharma, Asha; Tathireddy, Prashant; Rieth, Loren; Solzbacher, Florian; Song, Jung‐Han

doi:10.1016/j.snb.2012.03.073

Cited by 14 publications

(18 citation statements)

References 12 publications

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“…The laser pulses were 5 ns in duration, with a repetition rate of 100 Hz, and the laser fluence was 1500 mJ/cm 2 . The details of the laser ablation system are reported in Yoo et al (2012a).…”

Section: Methodsmentioning

confidence: 99%

“…In UEAs, oxygen plasma etching (OPE) with an aluminium foil mask has conventionally been used to etch an insulation material, Parylene-C, from the electrode tip. The demand for the development of microelectrodes that exhibit sophisticated geometries with different electrode heights (Bhandari et al, 2008) in UEAs is leading a shift of deinsulation methods from oxygen plasma etching using an aluminium foil mask to laser etching, as laser etching makes the deinsulation of individual tips in the UEA possible (Yoo et al, 2012a). Furthermore, the laser deinsulation process is attractive for the large-scale production of microelectrode arrays because it is less time consuming and highly reproducible.…”

Section: Introductionmentioning

confidence: 99%

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

Yoo

Negi

Tathireddy

et al. 2013

Journal of Neuroscience Methods

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Implantable microelectrodes provide a measure to electrically stimulate neurons in the brain and spinal cord and record their electrophysiological activity. A material with a high charge capacity such as activated or sputter-deposited iridium oxide film (AIROF or SIROF) is used as an interface. The Utah electrode array (UEA) uses SIROF for its interface material with neural tissue and oxygen plasma etching (OPE) with an aluminium foil mask to expose the active area, where the interface between the electrode and neural tissue is formed. However, deinsulation of Parylene-C using OPE has limitations, including the lack of uniformity in the exposed area and reproducibility. While the deinsulation of Parylene-C using an excimer laser is proven to be an alternative for overcoming the limitations, the iridium oxide (IrOx) suffers from fracture when high laser fluence (>1000 mJ/cm2) is used. Iridium (Ir), which has a much higher fracture resistance than IrOx, can be deposited before excimer laser deinsulation and then the exposed Ir film area can be activated by electrochemical treatment to acquire the AIROF. Characterisation of the laser-ablated Ir film and AIROF by surface analysis (X-ray photoelectron spectroscopy, scanning electron microscope, and atomic force microscope) and electrochemical analysis (electrochemical impedance spectroscopy, and cyclic voltammetry) shows that the damage on the Ir film induced by laser irradiation is significantly less than that on SIROF, and the AIROF has a high charge storage capacity. The results show the potential of the laser deinsulation technique for use in high performance AIROF-coated UEA fabrication.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Yoo

Negi

Tathireddy

et al. 2013

Journal of Neuroscience Methods

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“…Test structures and UEA devices were fabricated to investigate the deinsulation of the process, following the procedures outlined above, and in previous reports [22, 29, 37]. The first step in the deinsulation process is to ablate the Parylene layer, using an excimer laser micromachining system.…”

Section: Resultsmentioning

confidence: 99%

“…SIROF test structures were deinsulated by using 100 laser pulses with fluence of 1500 mJ/cm 2 with pulse duration of 5 ns and frequency of 100 Hz, adopted from Yoo et al . [29]. …”

Section: Methodsmentioning

confidence: 99%

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Self-aligned tip deinsulation of atomic layer deposited Al₂O₃and parylene C coated Utah electrode array based neural interfaces

Xie¹,

Rieth²,

Negi³

et al. 2014

J. Micromech. Microeng.

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The recently developed alumina and Parylene C bi-layer encapsulation improved the lifetime of neural interfaces. Tip deinsulation of Utah electrode array based neural interfaces is challenging due to the complex 3D geometries and high aspect ratios of the devices. A three-step self-aligned process was developed for tip deinsulation of bilayer encapsulated arrays. The deinsulation process utilizes laser ablation to remove Parylene C, O2 reactive ion etching to remove carbon and Parylene residues, and buffered oxide etch to remove alumina deposited by atomic layer deposition, and expose the IrOx tip metallization. The deinsulated iridium oxide area was characterized by scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, and electrochemical impedance spectroscopy to determine the morphology, surface morphology, composition, and electrical properties of the deposited layers and deinsulated tips. The alumina layer was found to prevent the formation of micro cracks on iridium oxide during the laser ablation process, which has been previously reported as a challenge for laser deinsulation of Parylene films. The charge injection capacity, charge storage capacity, and impedance of deinsulated iridium oxide were characterized to determine the deinsulation efficacy compared to Parylene-only insulation. Deinsulated iridium oxide with bilayer encapsulation had higher charge injection capacity (240 vs 320 nC) and similar electrochemical impedance (2.5 vs 2.5 kΩ) compared to deinsulated iridium oxide with only Parylene coating for an area of 2 × 10−4 cm2. Tip impedances were in the ranges of 20 to 50 kΩ, with median of 32 KΩ and standard deviation of 30 kΩ, showing the effectiveness of the self-aligned deinsulation process for alumina and Parylene C bi-layer encapsulation. The relatively uniform tip impedance values demonstrated the consistency of tip exposures.

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3D silicone rubber interfaces for individually tailored implants

Stieghorst

Bondarenkova

Burblies

et al. 2015

Biomed Microdevices

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For the fabrication of customized silicone rubber based implants, e.g. cochlear implants or electrocortical grid arrays, it is required to develop high speed curing systems, which vulcanize the silicone rubber before it runs due to a heating related viscosity drop. Therefore, we present an infrared radiation based cross-linking approach for the 3D-printing of silicone rubber bulk and carbon nanotube based silicone rubber electrode materials. Composite materials were cured in less than 120 s and material interfaces were evaluated with scanning electron microscopy. Furthermore, curing related changes in the mechanical and cell-biological behaviour were investigated with tensile and WST-1 cell biocompatibility tests. The infrared absorption properties of the silicone rubber materials were analysed with fourier transform infrared spectroscopy in transmission and attenuated total reflection mode. The heat flux was calculated by using the FTIR data, emissivity data from the infrared source manufacturer and the geometrical view factor of the system.

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Excimer-laser deinsulation of Parylene-C coated Utah electrode array tips

Cited by 14 publications

References 12 publications

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

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

Self-aligned tip deinsulation of atomic layer deposited Al₂O₃and parylene C coated Utah electrode array based neural interfaces

3D silicone rubber interfaces for individually tailored implants

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Excimer-laser deinsulation of Parylene-C coated Utah electrode array tips

Cited by 14 publications

References 12 publications

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

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

Self-aligned tip deinsulation of atomic layer deposited Al2O3and parylene C coated Utah electrode array based neural interfaces

3D silicone rubber interfaces for individually tailored implants

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Self-aligned tip deinsulation of atomic layer deposited Al₂O₃and parylene C coated Utah electrode array based neural interfaces