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@PHDTHESIS{RincnMontes:891143,
author = {Rincón Montes, Viviana},
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 = {FZJ-2021-01392},
isbn = {978-3-95806-553-6},
series = {Schriften des Forschungszentrums Jülich Reihe Information
/ Information},
pages = {XII, 173},
year = {2021},
note = {Dissertation, RWTH Aachen University, 2021},
abstract = {With the ultimate goal to restore vision in blind patients,
visual prostheses have been developed tointerface and
modulate the electrical activity of different neuronal
structures along the visualpathway, targeting mainly the
visual cortex, the optic nerve, and the retina. Thus,
prostheticdevices that stimulate electrically the retina
have been employed to treat blind patients with
retinaldegenerative diseases such as age-related macular
degeneration and retinitis pigmentosa, whichcomprise the
third leading cause of blindness worldwide. In the last
decades, the development ofretinal implants with commercial
approval and those used in clinical trials has shown
meaningfulprogress towards the restoration of useful vision.
Nonetheless, the recent withdrawal of currentretinal
implants from the market exhorts the scientific community to
join and enhance efforts toimprove the technology and the
efficiency of such devices to achieve further steps in the
restorationof vision.Aiming at a new generation of retinal
implants, the BiMEA consortium has proposed thedevelopment
of a bidirectional microelectrode array (BiMEA) to enable a
bidirectionalcommunication with the retina. To this end,
penetrating neural probes were proposed to allowaccess to
the intraretinal space and to modulate and record
simultaneously the electrical activity ofthe retina. To
further develop the BiMEA strategy, this work exposes the
development and in vitrovalidation of BiMEA probes, setting
in turn the groundwork for the future development of
novelintraretinal implants.First, the BiMEA concept was
validated in healthy and degenerated ex-planted mouse
retinas usingsilicon-based devices, thereby demonstrating
the feasibility of a bidirectional communicationbetween the
retina and a prosthetic device. Thus, the stimulation of the
inner retina with safeelectrical stimuli while recording the
neuronal activity of the output neurons of the retina,
theganglion cells, was achieved. Going a step further,
intraretinal devices based on flexible materialswere
developed and optimized to better match the anatomy and the
mechanical properties of theretina while fulfilling the
insertion requirements of such devices. Hence, flexible
intraretinalprobes with miniaturized shanks 7 μm thick and
145 μm long were successfully inserted into thethin retina.
As a result, local field potentials and the spiking activity
of both, healthy anddegenerated retinas, were recorded.
Moreover, electrically evoked potentials were captured
afterapplying charge densities as low as 81.5
μC/cm2.Furthermore, a systematic study to validate the
acute performance of both silicon and flexibleBiMEAs was
conducted. This study revealed that flexible penetrating
probes based onparylene-C with a shank width as narrow as 50
μm diminished the acute insertion footprint ofintraretinal
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
insertionof $93\%.$ Consequently, the development of
intraretinal devices open the door for closed loopfeedback
systems, offering the possibility to track and acknowledge
in situ the electrical activityof 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 thedevelopment of
intraretinal implants.},
cin = {IBI-3},
cid = {I:(DE-Juel1)IBI-3-20200312},
pnm = {553 - Physical Basis of Diseases (POF3-553)},
pid = {G:(DE-HGF)POF3-553},
typ = {PUB:(DE-HGF)3 / PUB:(DE-HGF)11},
urn = {urn:nbn:de:0001-2021080905},
url = {https://juser.fz-juelich.de/record/891143},
}