Single and Multisite Graphene-Based Electroretinography Recording Electrodes: A Benchmarking Study

Electroretinography (ERG) is a clinical test employed to understand and diagnose many retinopathies. ERG is usually performed by placing a macroscopic ring gold wire electrode on the cornea while flashing light onto the eye to measure changes in the transretinal potential. However, macroscopic gold electrodes are severely limiting since they do not provide a flexible interface to contact the sensitive corneal tissue, making this technique highly uncomfortable for the patient. Another major drawback is the opacity of gold electrodes, which only allows them to record the ERG signal on the corneal periphery, preventing central ERG recordings. To overcome the limitations of metal-based macroscopic ERG electrodes, flexible electrodes are fabricated using graphene as a transparent, flexible, and sensitive material. The transparency of the graphene is exploited to fabricate microelectrode arrays (MEAs) that are able to perform multisite recording on the cornea. The graphene-based ERG electrodes are benchmarked against the widely used gold electrodes in a P23H rat model with photoreceptor degeneration. This study shows that the graphene-based ERG electrodes can faithfully record ERGs under a wide range of conditions (light intensity, stage of photoreceptor degeneration, etc.) while offering additional benefits for ERG recordings such as transparency and flexibility.
J.d.l.C. and D.N. contributed equally to this work. This project received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement nos. 881603 (GrapheneCore3). This work was within the project FIS2017-85787-R funded by the “Ministerio de Ciencia, Innovación y Universidades” of Spain, the “Agencia Estatal de Investigación (AEI),” and the “Fondo Europeo de Desarrollo Regional (FEDER/UE).” Support was also provided by the French state funds managed by the Agence Nationale de la Recherche within the Programme Investissements d'Avenir, LABEX LIFESENSES (ANR-10-LABX-65) and IHU FOReSIGHT (ANR-18-IAHU-0001). The ICN2 is supported by the Severo Ochoa Centres of Excellence program, funded by the Spanish Research Agency (AEI, grant no. SEV-2017-0706), and by the CERCAProgram/Generalitat de Catalunya. E.d.C. acknowledges the Spanish MINECO Juan de la Cierva Fellowship JC-2015-25201. This work made use of the Spanish ICTS Network MICRONANOFABS partially supported by MICINN and the ICTS “NANBIOSIS,” more specifically by the Micro-NanoTechnology Unit of the CIBER in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN) at the IMB-CNM. J.d.l.C. would like to thank Laura García for the work on the images and figures throughout the whole paper writing process. E.d.C acknowledges the grant RYC2019-027879-I financed by MCIN/AEI /10.13039/501100011033. The project leading to these results have received funding from “la Caixa” Foundation (ID 100010434), under the agreement LCF/PR/HR19/52160003. These activities are co-funded with 50% by the European Regional Development Fund under the framework of the ERFD Operative Programme for Catalunya 2014–2020 with the support of the Department de Recerca i Universitat (GraphCAT 001-P-001702).