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TY - THES AU - Rincón Montes, Viviana TI - Development, characterization, and application of intraretinal implants VL - 67 PB - RWTH Aachen University VL - Dissertation CY - Jülich M1 - RWTH-2021-06382 SN - 978-3-95806-553-6 T2 - Schriften des Forschungszentrums Jülich. Reihe Information = information SP - 1 Online-Ressource : Illustrationen, Diagramme PY - 2021 N1 - Druckausgabe: 2021. - Onlineausgabe: 2021. - Auch veröffentlicht auf dem Publikationsserver der RWTH Aachen University N1 - Dissertation, RWTH Aachen University, 2021 AB - 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 LB - PUB:(DE-HGF)11 ; PUB:(DE-HGF)3 DO - DOI:10.18154/RWTH-2021-06382 UR - https://publications.rwth-aachen.de/record/821875 ER -