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@PHDTHESIS{RincnMontes:821875,
author = {Rincón Montes, Viviana},
othercontributors = {Offenhäusser, Andreas and Ingebrandt, Sven and Fitter,
Jörg},
title = {{D}evelopment, characterization, and application of
intraretinal implants},
volume = {67},
school = {RWTH Aachen University},
type = {Dissertation},
address = {Jülich},
publisher = {Forschungszentrum Jülich GmbH, Zentralbibliothek, Verlag},
reportid = {RWTH-2021-06382},
isbn = {978-3-95806-553-6},
series = {Schriften des Forschungszentrums Jülich. Reihe Information
= information},
pages = {1 Online-Ressource : Illustrationen, Diagramme},
year = {2021},
note = {Druckausgabe: 2021. - Onlineausgabe: 2021. - Auch
veröffentlicht auf dem Publikationsserver der RWTH Aachen
University; Dissertation, RWTH Aachen University, 2021},
abstract = {With the ultimate goal to restore vision in blind patients,
visual prostheses have been developed to interface and
modulate the electrical activity of different neuronal
structures along the visual pathway, targeting mainly the
visual cortex, the optic nerve, and the retina. Thus,
prosthetic devices that stimulate electrically the retina
have been employed to treat blind patients with
retinaldegenerative diseases such as age-related macular
degeneration and retinitis pigmentosa, which comprise the
third leading cause of blindness worldwide. In the last
decades, the development of retinal implants with commercial
approval and those used in clinical trials has shown
meaningful progress towards the restoration of useful
vision. Nonetheless, the recent withdrawal of current
retinal implants from the market exhorts the scientific
community to join and enhance efforts to improve the
technology and the efficiency of such devices to achieve
further steps in the restoration of vision. Aiming at a new
generation of retinal implants, the BiMEA consortium has
proposed the development of a bidirectional microelectrode
array (BiMEA) to enable a bidirectional communication with
the retina. To this end, penetrating neural probes were
proposed to allow access to the intraretinal space and to
modulate and record simultaneously the electrical activity
of the retina. To further develop the BiMEA strategy, this
work exposes the development and in vitro validation of
BiMEA probes, setting in turn the groundwork for the future
development of novel intraretinal implants. First, the BiMEA
concept was validated in healthy and degenerated ex-planted
mouse retinas using silicon-based devices, thereby
demonstrating the feasibility of a bidirectional
communication between the retina and a prosthetic device.
Thus, the stimulation of the inner retina with safe
electrical stimuli while recording the neuronal activity of
the output neurons of the retina, the ganglion cells, was
achieved. Going a step further, intraretinal devices based
on flexible materials were developed and optimized to better
match the anatomy and the mechanical properties of the
retina while fulfilling the insertion requirements of such
devices. Hence, flexible intraretinal probes with
miniaturized shanks 7 μm thick and 145 μm long were
successfully inserted into the thin retina. As a result,
local field potentials and the spiking activity of both,
healthy and degenerated retinas, were recorded. Moreover,
electrically evoked potentials were captured after applying
charge densities as low as 81.5 μC/cm2.Furthermore, a
systematic study to validate the acute performance of both
silicon and flexible BiMEAs was conducted. This study
revealed that flexible penetrating probes based on
parylene-C with a shank width as narrow as 50 μm diminished
the acute insertion footprint of intraretinal probes,
inducing lesions nearly 2.5 times the cross-section of the
probe. Moreover, electrical recordings had a maximum
signal-to-noise ratio of 12.37 and a success rate of
insertion of $93\%.$ Consequently, the development of
intraretinal devices open the door for closed loop feedback
systems, offering the possibility to track and acknowledge
in situ the electrical activity of the retina and the
success of the stimulation while adjusting accordingly the
stimuli. Even more, aiming future in vivo applications,
flexible BiMEA probes showed the potential for the
development of intraretinal implants.},
cin = {134210 / 130000},
ddc = {530},
cid = {$I:(DE-82)134210_20140620$ / $I:(DE-82)130000_20140620$},
typ = {PUB:(DE-HGF)11 / PUB:(DE-HGF)3},
doi = {10.18154/RWTH-2021-06382},
url = {https://publications.rwth-aachen.de/record/821875},
}
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