In-vitro measurements from porcine retinal tissue stimulated by a photovoltaic implant with 3D carbon electrodes

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Abstract

Purpose : Previous studies have documented the fabrication, electrical properties and biocompatibility of 3D pyrolytic carbon pillars. The purpose of the present study was to extend this experience by developing a complete photovoltaic (PV) device for subretinal implantation that can stimulate the neural elements of the retina.
Methods : Electrodes were fabricated from SU-8 resulting in ~35 µm tall carbon pillars on a 2x2 mm2 Si chip with local pn-junctions for each pillar and a pitch of 40 µm. The neuroretina from porcine eyes was positioned on the chip in a petri dish and bathed in PSS 1.6. The preparation was stimulated with sustained broad band white and transient 880 nm light during simultaneous recording of the membrane potential from cells in the superficial retina. Recordings were done both with intracellular glass microelectrode and a 16-channel multielectrode array. The intracellular location of the electrodes was subsequently documented using a confocal microscope (Zeiss LSM 800) after staining with propidium iodide and DAPI.
Results : During sustained illumination with white light the PV chip induced a depolarization of 10 mV in cells in the superficial retina, which is similar to the response after the addition of 40 mM KCl. Transient illumination by 100 ms pulses at 880 nm (Thorlabs M880L3 LED) showed 0.1 ms negative spikes of approximately -280 µV, followed by positive spikes of +50 µV that might be related to action potential in the tissue. The confocal images confirmed the intracellular location of the electrodes.
Conclusions : Light stimulation of subretinal photovoltaic elements composed
of biocompatible 3D pyrolytic carbon pillars can change the membrane potential
in cells in the superficial retina. This principle may potentially be the basis for
developing a prosthetic device to replace degenerated photoreceptors.
Original languageEnglish
JournalInvestigative Ophthalmology & Visual Science
Volume61
Issue number7
ISSN0146-0404
Publication statusPublished - 2020
EventARVO 2020 Annual Meeting - Baltimore, United States
Duration: 3 May 20207 May 2020

Conference

ConferenceARVO 2020 Annual Meeting
Country/TerritoryUnited States
CityBaltimore
Period03/05/202007/05/2020

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