An implantable microelectrode array for chronic in vivo epiretinal stimulation of the rat retina

Yoon, Eugene; Koo, Beomseo; Wong, Jordan; Elyahoodayan, Sahar; Weiland, James D.; Lee, C D; Petrossians, Artin; Meng, Ellis

doi:10.1088/1361-6439/abbb7d

Cited by 12 publications

(8 citation statements)

References 47 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In published work thus far, Parylene thermoforming has been used to produce devices with thermoformed functional regions (i.e. regions with thin film metal features) 1-5 mm in curvature diameter [1,[10][11][12][13][14] or non-functional regions (i.e. regions with bare Parylene) down to 0.25 mm in curvature diameter (with visible Parylene cracking) [1,13].…”

Section: Discussionmentioning

confidence: 99%

“…Thermoformed Parylene C has been used in numerous microfabricated medical devices [1,[10][11][12][13][14][15] with various geometries. Of note is the helix geometry, which can be used for strain relief, to interface with anatomical features such as nerves, muscle fibers, or blood vessels, or can be wrapped around cylindrical supports (such as catheters, stents, and probes) to produce 3D MEMS devices.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Characterization of thin film Parylene C device curvature and the formation of helices via thermoforming

Thielen

Meng

2023

J. Micromech. Microeng.

Self Cite

View full text Add to dashboard Cite

In microfabricated biomedical devices, flexible, polymer substrates are becoming increasingly preferred over rigid, silicon substrates because of their ability to conform to biological tissue. Such devices, however, are fabricated in a planar configuration, which results in planar devices that do not closely match the shape of most tissues. Thermoforming, a process which can permanently reshape thermoplastic polymers, can be used to transform flat, thin film, polymer devices with patterned metal features into complex three-dimensional (3D) geometries. This process extends the use of planar microfabrication to achieve 3D shapes which can more closely interface with the body. Common shapes include spheres, which can conform to the shape of the retina, cones, which can be used as a sheath to interface with an insertion stylet, and helices, which can be wrapped around nerves, blood vessels, muscle fibers, or be used as strain relief feature. This work characterizes the curvature of thin film Parylene C devices with patterned metal features built with varying Parylene thicknesses and processing conditions. Device curvature is caused by film stress in each Parylene and metal layer, which is characterized experimentally and by a mathematical model which estimates the effects of device geometry and processing on curvature. Using this characterization, an optimized process to thermoform thin film Parylene C devices with patterned metal features into 0.25 mm diameter helices while preventing cracking in the polymer and metal was developed.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Characterization of thin film Parylene C device curvature and the formation of helices via thermoforming

Thielen

Meng

2023

J. Micromech. Microeng.

Self Cite

View full text Add to dashboard Cite

show abstract

“…First, electrode size should be on the sub-micron scale for sensing of single vesicles or in small brain regions, such as Drosophila, which has brain regions that are less than 10 micrometers. [2,[4][5][6] Second, the electrode needs to have a long and thin tip for easy implantation with little damage. Third, the electrode material needs to have good electrochemical performance to ensure rapid sensing.…”

Section: Introductionmentioning

confidence: 99%

3D‐Printed Carbon Nanoneedle Electrodes for Dopamine Detection in Drosophila

Shao,

Zhao,

Dunham

et al. 2024

Angewandte Chemie

View full text Add to dashboard Cite

In vivo electrochemistry in small brain regions or synapses requires nanoelectrodes with long straight tips for submicron scale measurements. Nanoelectrodes can be fabricated using a Nanoscribe two‐photon printer, but annealed tips curl if they are long and thin. We propose a new pulling‐force strategy to fabricate a straight carbon nanoneedle structure. A micron‐width bridge is printed between two blocks. The annealed structure shrinks during pyrolysis, and the blocks create a pulling force to form a long, thin, and straight carbon bridge. Parameterization study and COMSOL modeling indicate changes in the block size, bridge size and length affect the pulling force and bridge shrinkage. Electrodes were printed on niobium wires, insulated with aluminum oxide, and the bridge cut with focused ion beam (FIB) to expose the nanoneedle tip. Annealed needle diameters ranged from 400 nm to 5.25 µm and length varied from 50.5 µm to 146 µm. The electrochemical properties are similar to glassy carbon, with good performance for dopamine detection with fast‐scan cyclic voltammetry. Nanoelectrodes enable biological applications, such as dopamine detection in a specific Drosophila brain region. Long and thin nanoneedles are generally useful for other applications such as cellular sensing, drug delivery, or gas sensing.

show abstract

“…Because of the manufacturing processes and geometrical characteristics, these implants lack important features, such as a high electrode density to improve spatial resolution [25], and low implant stiffness to match the elastic modulus of the neural tissue [26]. These limitations have motivated researchers and newly-founded neurotechnology ventures to focus on flexible thin polymer-based neural interfaces, which conform to curved surfaces and are mechanically compliant with the neural tissue [27][28][29][30][31][32][33]. Polyimide (PI), parylene-C and SU-8 are widely used in neural implants because they are biochemically and thermally stable, and processable with silicon-based microfabrication technologies [34][35][36].…”

Section: Introductionmentioning

confidence: 99%

Conformable neural interface based on off-stoichiometry thiol-ene-epoxy thermosets

Borda

Leccardi

Zollinger

et al. 2022

Preprint

View full text Add to dashboard Cite

Off-stoichiometry thiol-ene-epoxy (OSTE+) thermosets have recently gained attention for the rapid prototyping of microfluidic chips because they show low permeability to gases and little absorption of dissolved molecules, they allow direct low-temperature dry bonding without surface treatments, they have a low Young's modulus, and they can be manufactured via UV polymerisation. The compatibility with standard clean-room processes and the outstanding mechanical properties make OSTE+ an excellent candidate as a novel material for neural implants. Here we exploit OSTE+ to manufacture a conformable multilayer micro-electrocorticography array with 16 platinum electrodes coated with platinum black. The mechanical properties allow device conformability to curved surfaces such as the brain. The low permeability and strong adhesion between layers improve the stability of the device. Acute experiments in mice show the multimodal capacity of the array to record and stimulate the neural tissue by smoothly conforming to the mouse cortex. Devices are not cytotoxic, and immunohistochemistry stainings reveal only modest foreign body reaction after two and six weeks of implantation. This work introduces OSTE+ as a promising material in the field of implantable neural interfaces.

show abstract

An implantable microelectrode array for chronic in vivo epiretinal stimulation of the rat retina

Cited by 12 publications

References 47 publications

Characterization of thin film Parylene C device curvature and the formation of helices via thermoforming

Characterization of thin film Parylene C device curvature and the formation of helices via thermoforming

3D‐Printed Carbon Nanoneedle Electrodes for Dopamine Detection in Drosophila

Conformable neural interface based on off-stoichiometry thiol-ene-epoxy thermosets

Contact Info

Product

Resources

About