POLYRETINA restores light responses in vivo in blind Göttingen minipigs

Vagni, Paola; Leccardi, Marta Jole Ildelfonsa Airaghi; Vila, Charles-Henri; Zollinger, Elodie Geneviève; Sherafatipour, Golnaz; Wolfensberger, Thomas J.; Ghezzi, Diego

doi:10.1038/s41467-022-31180-z

Cited by 34 publications

(30 citation statements)

References 41 publications

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“…Further to ensuring initial cellular adhesion and growth support, the long-term biocompatibility and tissue response to the presence of a foreign object is an important consideration for any long-term success of such devices in vivo. [180][181][182] There are two major challenges associated with in vivo implanted electrodes; the initial insertion or implantation, which can cause trauma and damage to the surrounding tissue, and ongoing shear stress damage due to the inherent mechanical mismatch between the soft brain tissue (1-100 kPa) and a semi-conductor electrode (i.e. diamond with Young's modulus B1000 GPa).…”

Section: Long-term Implant Biocompatibilitymentioning

confidence: 99%

Semiconducting electrodes for neural interfacing: a review

et al. 2023

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Section: Long-term Implant Biocompatibilitymentioning

confidence: 99%

Semiconducting electrodes for neural interfacing: a review

et al. 2023

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“…[ 68–77 ] This approach has found application predominantly in retinal prostheses since the eye transparency allows the projection of patterned light to activate stimulators with high channel count and at high spatial resolution (Figure 3b). [ 32,78–83 ]…”

Section: Figurementioning

confidence: 99%

“…[68][69][70][71][72][73][74][75][76][77] This approach has found application predominantly in retinal prostheses since the eye transparency allows the projection of patterned light to activate stimulators with high channel count and at high spatial resolution (Figure 3b). [32,[78][79][80][81][82][83] While in retinal stimulation, the photovoltaic approach provided a solution to large-scale high-density stimulation, [78] challenges are still open for cortical interfaces. [84] Typically these challenges are in the area of electrical engineering, including low-power design, power transfer efficiency, high-data-rate telemetry, and data compression.…”

mentioning

confidence: 99%

Engineering Materials for Neurotechnology

Ghezzi

2023

Adv Eng Mater

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A crucial issue for a neural interface is the chronic foreign body reaction (FBR) upon implantation. [1][2][3] Avoiding the FBR, or at least reducing its severity, is necessary to preserve the long-term functioning of neural interfaces. [4][5][6] Yet, this is still an open research question. The FBR is traditionally described as a passive barrier encapsulating the device, altering the neural interface, and impairing implant-to-cell communication. [2,7,8] Besides acting as a passive insulating barrier, soluble factors released during the inflammatory and fibrotic process can accelerate device degradation and electrode corrosion. [9] The FBR is inevitable whenever any material becomes in contact with body fluids. [10] In contrast, materials engineering and advanced fabrication processes can minimize its severity, for example, by improving the mechanical compliance of the implant, decreasing the device size, and reducing implantation and chronic trauma. [3] One of the most common limitations of neural interfaces is the mechanical mismatch between the stiff neural implant and the soft neural tissue. This mismatch intensifies the neural damage and FBR caused by insertion, compression, and motion. [11] The neural tissue is curved, soft, dynamic, and subject to deformations caused, for example, by blood pulsation, respiratory pressure, and natural body movements. [11,12] By contrast, most neural interfaces are static and struggle to conform to neural tissue in static and dynamic conditions. A large body of research in neural interfaces addresses this issue using flexible, conformable, or stretchable neural interfaces (Figure 1).Polyimide (PI), parylene-C, and SU-8 are widely used materials in flexible neural interfaces. [13][14][15][16][17][18][19][20][21][22] The advantages of these materials are their biochemical and thermal stability, and their compatibility with clean-room microfabrication processes. [23][24][25] However, they exhibit high Young's modulus (GPa range) and limited elastic deformation (<3%). [26] Ultra-thin neural interfaces made of these materials still reach low bending stiffness if sufficiently thin (<15 μm) despite the high Young's modulus. [27] They can conform to a cylindrical body such as a nerve or a smooth brain surface (Figure 1a), thus reducing the FBR severity. [23] Moreover, ultra-thin neural interfaces with a small cross-sectional area also can minimize tissue damage during penetration (Figure 1b). [22,24,28] Conformability to cylindrical or smooth surfaces is sufficient in rodents, but more is needed for large and complex surfaces with gyri, like in primates, where spherical conformability is required. Because of the limited elastic deformation, conformability to convoluted surfaces is difficult to achieve with these materials. Compliance with neural macro-and micro-movements is also reduced. [26] Elastomers exhibit a lower Young's modulus of at least three orders of magnitude (MPa range) and a much broader elastic regime under strain (>20%). Bending stiffness is influenced by both thick...

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“…This guideline limits the size of a retinal array. Experimental arrays of larger size (up to 14 mm diameter) can be folded for insertion, then unfolded to cover greater peripheral areas 9 – 13 but require additional development before use in humans. Thus, there is a need to continue development of novel retinal arrays that incorporate new materials to meet the demands imposed by implantation (folded array for insertion through an eyewall incision) and function (large array to stimulate both central and peripheral retina).…”

Section: Introductionmentioning

confidence: 99%

Full-field, conformal epiretinal electrode array using hydrogel and polymer hybrid technology

Zhou¹,

Young²,

Valle³

et al. 2023

Sci Rep

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Shape-morphable electrode arrays can form 3D surfaces to conform to complex neural anatomy and provide consistent positioning needed for next-generation neural interfaces. Retinal prostheses need a curved interface to match the spherical eye and a coverage of several cm to restore peripheral vision. We fabricated a full-field array that can (1) cover a visual field of 57° based on electrode position and of 113° based on the substrate size; (2) fold to form a compact shape for implantation; (3) self-deploy into a curvature fitting the eye after implantation. The full-field array consists of multiple polymer layers, specifically, a sandwich structure of elastomer/polyimide-based-electrode/elastomer, coated on one side with hydrogel. Electrodeposition of high-surface-area platinum/iridium alloy significantly improved the electrical properties of the electrodes. Hydrogel over-coating reduced electrode performance, but the electrodes retained better properties than those without platinum/iridium. The full-field array was rolled into a compact shape and, once implanted into ex vivo pig eyes, restored to a 3D curved surface. The full-field retinal array provides significant coverage of the retina while allowing surgical implantation through an incision 33% of the final device diameter. The shape-changing material platform can be used with other neural interfaces that require conformability to complex neuroanatomy.

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POLYRETINA restores light responses in vivo in blind Göttingen minipigs

Cited by 34 publications

References 41 publications

Semiconducting electrodes for neural interfacing: a review

Semiconducting electrodes for neural interfacing: a review

Engineering Materials for Neurotechnology

Full-field, conformal epiretinal electrode array using hydrogel and polymer hybrid technology

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