Long-term implants of Parylene-C coated microelectrodes

Schmidt, Edward M.; McIntosh, J.S.; Bak, Martin

doi:10.1007/bf02441836

Cited by 224 publications

(135 citation statements)

References 8 publications

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“…14 Parylene C is a highly biocompatible material, which has a long history of use in the field of medical implants and microdevices, such as pacemakers, 15 sensors, 16 and microelectrodes. 17 Besides biocompatibility, the material has been widely used for encapsulation due to its excellent electrical, thermal, and physical properties. These inherent properties, however, are thickness dependent, [18][19][20] which is attributed to a transition from an amorphous to a semicrystalline structure as thickness increases.…”

Section: Introductionmentioning

confidence: 99%

Surface Chemistry and Microtopography of Parylene C Films Control the Morphology and Microtubule Density of Cardiac Myocytes

Trantidou

Humphrey

Poulet

et al. 2016

Tissue Engineering Part C: Methods

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Cell micropatterning has certainly proved to improve the morphological and physiological properties of cardiomyocytes in vitro; however, there is little knowledge on the single cell-scaffold interactions that influence the cells' development and differentiation in culture. In this study, we employ hydrophobic/hydrophilic micropatterned Parylene C thin films (2-10 mm) as cell microscaffolds that can control the morphology and microtubule density of neonatal rat ventricular myocytes (NRVM) by regulating their adhesion area on Parylene through a thickness-dependent hydrophobicity. Structured NRVM on thin films tend to bridge across the hydrophobic areas, demonstrating a more spread-out shape and sparser microtubule organization, while cells on thicker films adopt a cylindrical (in vivo-like) shape (contact angles at the level of the nucleus are 64.51°and 84.73°, respectively) and a significantly ( p < 0.05) denser microtubule structure. Ion scanning microscopy on NRVM revealed that cells on thicker membranes were significantly ( p < 0.05) smaller in volume, but more elongated. The cylindrical shape and a significantly denser microtubule structure indicate the ability to influence cardiomyocyte phenotype using patterning and manipulation of hydrophilicity. These combined bioengineering strategies are promising tools in the generation of more representative cardiomyocytes in culture.

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Section: Introductionmentioning

confidence: 99%

Surface Chemistry and Microtopography of Parylene C Films Control the Morphology and Microtubule Density of Cardiac Myocytes

Trantidou

Humphrey

Poulet

et al. 2016

Tissue Engineering Part C: Methods

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“…(14) Oxidative degradation, including thermal and photooxidation, has been reported to cause failures in Parylene films. (15,16) Shaw et al have suggested that annealing films directly after Parylene deposition would result in a film that is more resistant to oxidation.…”

Section: Introductionmentioning

confidence: 99%

Effect of Thermal and Deposition Processes on Surface Morphology, Crystallinity, and Adhesion of Parylene-C

Hsu

Rieth

Kammer

et al. 2008

Sensors and Materials

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Neural interface devices have been developed for neural science and neuroprosthetics applications to record and stimulate neural signals. Chemical-vapor-deposited Parylene-C films were studied as an encapsulation material for such an implantable device. The surface morphology of an implant affects its biocompatibility; thus, the Parylene-C surface morphology was investigated as a function of the precursor sublimation rate by atomic force microscopy. We found that high precursor sublimation rates resulted in slightly higher root-mean-square surface roughnesses (from 5.78 to 9.53 nm for deposition rates from 0.015 to 0.08 g/min). The crystallinity affects the physical properties of semicrystalline polymers, and various heat treatments were found to modify the crystallinity of Parylene-C films, as assessed by X-ray diffraction (XRD). The XRD peak at 2θ = ~14.5° increased in intensity and decreased in full width at half maximum with increasing annealing temperature, indicating an increase in film crystallinity. Poor adhesion would compromise the protection offered by Parylene-C coatings. The adhesion between Parylene-C and silicon, amorphous silicon carbide, and boron silicate glass substrates were evaluated using the standard tape adhesion test from the American Society for Testing and Materials (ASTM) in an attempt to minimize the occurrence of delamination failures. The tape adhesion tests indicated strong adhesion for all the as-deposited Parylene films with the application of an adhesion promoter (Silquest A-174 ® silane). However, annealing the deposited films at temperatures from 85 to 150°C in air for 20 min reduced film adhesion, and also the adhesion testing procedure used significantly affects the results obtained. Supporting evidence suggested that the thermal stress generated in the films weakened the adhesive force. We concluded that 88 Sensors and Materials, Vol. 20, No. 2 (2008) the Parylene-C film properties (surface morphology, crystallinity, and adhesion) changed during deposition and thermal annealing, suggesting that the Parylene-C film properties can be tailored and that, with care, failure due to film delamination can be avoided.

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“…More importantly, its pinhole-free conformal coating ability enables fabrication of high-aspect-ratio hollow tubes in a single material layer. Microfabricated parylenebased devices have been reported in applications such as implantable microelectrodes, neurocages, neuroprobes and retinal prostheses [14][15][16][17][18][19]. These examples support utilization of parylene for flexible and implantable biomedical microdevices.…”

Section: Materials Selectionmentioning

confidence: 91%

Implantable micromechanical parylene-based pressure sensors for unpowered intraocular pressure sensing

Chen

Rodger

Agrawal

et al. 2007

J. Micromech. Microeng.

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This paper presents the first implantable, unpowered, parylene-based microelectromechanical system (MEMS) pressure sensor for intraocular pressure (IOP) sensing. From in situ mechanical deformation of the compliant spiral-tube structures, this sensor registers pressure variations without electrical or powered signal transduction of any kind. Micromachined high-aspect-ratio polymeric hollow tubes with different geometric layouts are implemented to obtain high-sensitivity pressure responses. An integrated device packaging method has been developed toward enabling minimally invasive suture-less needle-based implantation of the device. Both in vitro and ex vivo device characterizations have successfully demonstrated mmHg resolution of the pressure responses. In vivo animal experiments have also been conducted to verify the biocompatibility and functionality of the implant fixation method inside the eye. Using the proposed implantation scheme, the pressure response of the implant can be directly observed from outside the eye under visible light, with the goal of realizing convenient, direct and faithful IOP monitoring in glaucoma patients.

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Long-term implants of Parylene-C coated microelectrodes

Cited by 224 publications

References 8 publications

Surface Chemistry and Microtopography of Parylene C Films Control the Morphology and Microtubule Density of Cardiac Myocytes

Surface Chemistry and Microtopography of Parylene C Films Control the Morphology and Microtubule Density of Cardiac Myocytes

Effect of Thermal and Deposition Processes on Surface Morphology, Crystallinity, and Adhesion of Parylene-C

Implantable micromechanical parylene-based pressure sensors for unpowered intraocular pressure sensing

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