Design, Fabrication, and Evaluation of a Parylene Thin-Film Electrode Array for Cochlear Implants

Xu, Yuchen; Luo, Chuan; Zeng, Fan‐Gang; Middlebrooks, John C.; Lin, Harrison W.; You, Zheng

doi:10.1109/tbme.2018.2850753

Cited by 17 publications

(12 citation statements)

References 38 publications

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“…Alternatively, some studies measured spatial spreads at different dB levels above threshold for different modalities, for example 20 and 6 dB above threshold for acoustic and electric stimulation, respectively ( Snyder et al, 2004 ). More recent studies that have evaluated novel stimulation modalities and compared them to acoustic and/or electric responses compared spatial spreads at a given response strength, typically at cumulative d ′ values of 2–4 ( Middlebrooks and Snyder, 2007 ; Bierer et al, 2010 ; Moreno et al, 2011 ; Richter et al, 2011 ; George et al, 2015 ; Xu et al, 2019 ; Dieter et al, 2019 ; Keppeler et al, 2020 ). Thus, to remain consistent with these previous studies, we also compared spectral spreads from acoustic, magnetic, and electric stimulation at cumulative discrimination indexes of 2 and 4.…”

Section: Methodsmentioning

confidence: 99%

Magnetic stimulation allows focal activation of the mouse cochlea

Lee

Seist

McInturff

et al. 2022

eLife

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Cochlear implants (CIs) provide sound and speech sensations for patients with severe to profound hearing loss by electrically stimulating the auditory nerve. While most CI users achieve some degree of open set word recognition under quiet conditions, hearing that utilizes complex neural coding (e.g., appreciating music) has proved elusive, probably because of the inability of CIs to create narrow regions of spectral activation. Several novel approaches have recently shown promise for improving spatial selectivity, but substantial design differences from conventional CIs will necessitate much additional safety and efficacy testing before clinical viability is established. Outside the cochlea, magnetic stimulation from small coils (micro-coils) has been shown to confine activation more narrowly than that from conventional microelectrodes, raising the possibility that coil-based stimulation of the cochlea could improve the spectral resolution of CIs. To explore this, we delivered magnetic stimulation from micro-coils to multiple locations of the cochlea and measured the spread of activation utilizing a multielectrode array inserted into the inferior colliculus; responses to magnetic stimulation were compared to analogous experiments with conventional microelectrodes as well as to responses when presenting auditory monotones. Encouragingly, the extent of activation with micro-coils was ~60% narrower compared to electric stimulation and largely similar to the spread arising from acoustic stimulation. The dynamic range of coils was more than three times larger than that of electrodes, further supporting a smaller spread of activation. While much additional testing is required, these results support the notion that magnetic micro-coil CIs can produce a larger number of independent spectral channels and may therefore improve auditory outcomes. Further, because coil-based devices are structurally similar to existing CIs, fewer impediments to clinical translational are likely to arise.

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Section: Methodsmentioning

confidence: 99%

Magnetic stimulation allows focal activation of the mouse cochlea

Lee

Seist

McInturff

et al. 2022

eLife

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“…At present, the implantable power supplies and speech processors are already available in clinical products, but the implantable microphones are the difficult point for a breakthrough. In recent years, various forms of fully implantable microphones and electrode arrays are reported, such as the MEMS array system composed of several individual active piezoresistive thin diaphragms and actuated by acoustic waves (Figure 7c), [ 217 ] spiral‐shaped piezoelectric MEMS cantilever array system (Figure 7d), [ 30 ] parylene thin‐film cochlear implant electrode arrays (Figure 7e), [ 218 ] etc. However, to be accepted as a mainstream alternative, many efforts should be spent to provide cochlear implant patients with similar or higher sound quality to their external counterparts.…”

Section: Device Configurations and Applicationsmentioning

confidence: 99%

mentioning

confidence: 99%

Materials and Biomedical Applications of Implantable Electronic Devices

Liu

et al. 2022

Adv Materials Technologies

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The implantable electronic devices have attracted great attention for solving clinical problems ranging from monitoring psychological states to electro‐organ transplantation. The ongoing challenges are the selection of suitable materials in a target device configuration for biomedical applications. To address the ongoing challenges, there are several interesting questions: what types of electronic materials can be used as the implantable electrodes? What types of materials can be used as the substrates for the implantable electronic devices? What types of materials can be used as membranes and encapsulations? What types of device configurations are there for implantable biomedical applications? What types of applications are for implantable electronic devices? This review will highlight the attempts for addressing these questions. This review will explore the fundamentals and practical aspects of a variety of materials and their biomedical applications in implantable electronic devices. It is anticipated that this review could provide new opportunities for the construction of future implantable electronic devices, as well as related applications for disease diagnosis and therapy.

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“…Parylene C (poly(2-chloro- p -xylylene)) was the first type to rate the USP class VI in the family, and it is impermeable to water and air, chemically inert, biocompatible, insulating and optical transparent [ 1 ]. Due to these excellent properties, it is widely applied to protect and insulate biomedical devices, such as neural interfaces [ 2 ], biomedical sensors [ 3 , 4 ] and implantable prostheses [ 5 , 6 ], as well as to modify culture substrates [ 7 , 8 ]. Implantable neural electrodes, the common tools for neural stimulation and neural recording, also require insulating materials, such as Parylene, as uniform coatings which provide insulation and protect against corrosion [ 9 , 10 ].…”

Section: Introductionmentioning

confidence: 99%

Parylene C as an Insulating Polymer for Implantable Neural Interfaces: Acute Electrochemical Impedance Behaviors in Saline and Pig Brain In Vitro

Zhang

Song

et al. 2022

Polymers

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Parylene is used as encapsulating material for medical devices due to its excellent biocompatibility and insulativity. Its performance as the insulating polymer of implantable neural interfaces has been studied in electrolyte solutions and in vivo. Biological tissue in vitro, as a potential environment for characterization and application, is convenient to access in the fabrication lab of polymer and neural electrodes, but there has been little study investigating the behaviors of Parylene in the tissue in vitro. Here, we investigated the electrochemical impedance behaviors of Parylene C polymer coating both in normal saline and in a chilled pig brain in vitro by performing electrochemical impedance spectroscopy (EIS) measurements of platinum (Pt) wire neural electrodes. The electrochemical impedance at the representative frequencies is discussed, which helps to construct the equivalent circuit model. Statistical analysis of fitted parameters of the equivalent circuit model showed good reliability of Parylene C as an insulating polymer in both electrolyte models. The electrochemical impedance measured in pig brain in vitro shows marked differences from that of saline.

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Design, Fabrication, and Evaluation of a Parylene Thin-Film Electrode Array for Cochlear Implants

Abstract: The present TFEA and micro-fabrication method represent a step closer towards an automated process replacing the labor-intensive and expensive manual assembly of electrode arrays in most neural prostheses including the cochlear implant.

Cited by 17 publications

References 38 publications

Magnetic stimulation allows focal activation of the mouse cochlea

Magnetic stimulation allows focal activation of the mouse cochlea

Materials and Biomedical Applications of Implantable Electronic Devices

Parylene C as an Insulating Polymer for Implantable Neural Interfaces: Acute Electrochemical Impedance Behaviors in Saline and Pig Brain In Vitro

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