An Electrochemical Investigation of the Impact of Microfabrication Techniques on Polymer-Based Microelectrode Neural Interfaces

Hara, Seth A.; Kim, Brian J.; Kuo, Jen-Tsai; Meng, Ellis

doi:10.1109/jmems.2015.2434827

Cited by 11 publications

(9 citation statements)

References 43 publications

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“…Prior to PEG encapsulation and insertion into the ZIF, hippocampal arrays were potentiostatically cleaned using cyclic voltammetry (CV) [41] and analyzed using electrochemical impedance spectroscopy (EIS). CV (−0.2 V to 1.2 V, scan rate of 250 mVs −1 ) was run on each individual electrode trace for 30 cycles in 0.5 M H 2 SO 4 purged with N 2 for five minutes prior to scanning.…”

Section: Materialsand Methodsmentioning

confidence: 99%

Acutein vivotesting of a conformal polymer microelectrode array for multi-region hippocampal recordings

Hirschberg

Scholten

et al. 2018

J. Neural Eng.

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Section: Materialsand Methodsmentioning

confidence: 99%

Acutein vivotesting of a conformal polymer microelectrode array for multi-region hippocampal recordings

Hirschberg

Scholten

et al. 2018

J. Neural Eng.

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“…Improved plasma systems or alternative techniques such as laser ablation [72] may be able to decrease oxidation during the deinsulation process. Novel neural electrode technologies incorporating PPX-C are constantly in development, and while common characterization techniques such as EIS have been used to assess heat treatment effects on impedance [73], we have not found impedance to be predictive of PPX-C stability during aging. In such cases, additional spectroscopic methods and RAA can provide deeper insight into possible changes to PPX-C chemistry due to high-temperature processing, as well as an indication of PPX-C resilience to aggressive environments encountered in vivo.…”

Section: Effect Of the Deinsulation Process On Ppx-cmentioning

confidence: 62%

Analytical characterization of Parylene-C degradation mechanisms on Utah arrays: evaluation of in vitro Reactive Accelerated Aging model compared to multiyearin vivoimplantation

Caldwell

Street

Sharma

et al. 2019

Preprint

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Implantable neural microelectrodes are integral components of neuroprosthetic technologies and can transform treatments for many neural-mediated disorders. However, dielectric material degradation during long-term (> 1 year) indwelling periods restricts device functional lifetimes to a few years. This comprehensive work carefully investigates in vivo material degradation and also explores the ability of in vitro Reactive Accelerated Aging (RAA) to evaluate implant stability. Parylene C-coated Utah electrode arrays (UEAs) implanted in feline peripheral nerve for 3.25 years were explanted and compared to RAA-processed devices, aged in phosphate buffered saline (PBS) + 20 mM H 2 O 2 at either 67 or 87 °C (28 or 7 days, respectively). Electron microscopy revealed similar physical damage characteristics between explants and RAA (87° C) devices. Parylene C degradation was overwhelmingly apparent for UEAs from both RAA cohorts. Controls aged in PBS alone displayed almost no damage. Spectroscopic characterization (EDX, XPS, FTIR) found clear indications of oxidation and chlorine abstraction for parylene C aged in vivo. While in vitro aging was also accompanied by signs of oxidation, changes in the chemistry in vivo and in vitro were statistically different. Analysis of RAAaged devices identified UEA fabrication approaches that may greatly improve device resistance to degradation. This work underscores the need for an improved understanding of in vivo damage mechanisms, to facilitate the critical need for representative in vitro accelerated testing paradigms for long-term implants.

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“…The problem with processing polymers as structural materials is their inability to withstand high temperatures that limits the use of some of the common microfabrication methods, i.e., certain deposition techniques (Kim and Meng, 2015 ). Certain microfabrication processes, such as thermoforming, electrochemical cleaning, or heat treatment can alter polymer electrodes' electrical properties, thus the methods should be chosen so that the final implant meets required electrical parameters (Hara et al, 2015 ). Polymers are characterized with water uptake that causes delamination, mechanical, and adhesion problems in vivo and can change probe's electrical performance over time (Jorfi et al, 2014 ).…”

Section: Polymer Microelectrodesmentioning

confidence: 99%

“…Moulding two patterned sheets of Parylene- C over tapered stainless steel wire template can be employed to form conical microchannel promoting neuronal ingrowth in novel sheath-electrodes (Figure 7E ) (Kim et al, 2013 ; Kuo et al, 2013 ; Hara et al, 2015 ). However, thermal treatment of Parylene-C induces changes in its crystallinity, and results in increased stiffness, tensile strength, and impedance of the probe (Kim et al, 2014 ; Hara et al, 2015 ). Most polymers can be patterned in a process of laser ablation in high power light Nd: YAG, CO 2 , or excimer lasers.…”

Section: Polymer Microelectrodesmentioning

confidence: 99%

Neural Interfaces for Intracortical Recording: Requirements, Fabrication Methods, and Characteristics

2017

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Implantable neural interfaces for central nervous system research have been designed with wire, polymer, or micromachining technologies over the past 70 years. Research on biocompatible materials, ideal probe shapes, and insertion methods has resulted in building more and more capable neural interfaces. Although the trend is promising, the long-term reliability of such devices has not yet met the required criteria for chronic human application. The performance of neural interfaces in chronic settings often degrades due to foreign body response to the implant that is initiated by the surgical procedure, and related to the probe structure, and material properties used in fabricating the neural interface. In this review, we identify the key requirements for neural interfaces for intracortical recording, describe the three different types of probes—microwire, micromachined, and polymer-based probes; their materials, fabrication methods, and discuss their characteristics and related challenges.

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An Electrochemical Investigation of the Impact of Microfabrication Techniques on Polymer-Based Microelectrode Neural Interfaces

Cited by 11 publications

References 43 publications

Acutein vivotesting of a conformal polymer microelectrode array for multi-region hippocampal recordings

Acutein vivotesting of a conformal polymer microelectrode array for multi-region hippocampal recordings

Analytical characterization of Parylene-C degradation mechanisms on Utah arrays: evaluation of in vitro Reactive Accelerated Aging model compared to multiyearin vivoimplantation

Neural Interfaces for Intracortical Recording: Requirements, Fabrication Methods, and Characteristics

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