WP5: Integration of advanced neural interfaces
Task 5.1: Fabrication of SELINE electrodes (SMANIA)
From M2 to M5, SMANIA will fabricate a set of traditional SELINE electrodes (22 pieces). A part of them (10 pieces) will be used by the partners to test their components / techniques. The remaining part (12 pieces) will be then integrated (during Task 5.3) with the additional features and components developed in the project course. The same will be done from M18 to M21, with the production of additional 22 pieces.
Polyimide electrodes will be manufactured by means of thin films deposition (e.g. spin coating, sputtering, evaporation) and patterning (e.g. microlithography, wet and dry etching) techniques in a clean room environment. Electrode packaging will be completed with printed circuit boards, connection wires and biocompatible silicone, by following an already certified industrial process.
Task 5.2: Polyimide functionalization and masking (SSSA, All)
This task will address the surface treatment of polyimide, in order to facilitate the covalent attachment of the engineered hydrogels developed within Task 3.1, and a proper masking strategy, to leave the conductive sites of the electrodes uncoated (thus able to record neural signals).
Functionalization strategies will be carried out by taking into account the nature of the hydrogels. Concerning zwitterionic hydrogels, by illumination with light at l = 310 - 350 nm, 4-azidophenyl group will be transformed into a highly reactive intermediate nitrene biradical (R-N:). This, via C-H insertion will react with organic materials such as electrode polyimide surface, as well as with the copolymer chains. The result will be a covalently crosslinked copolymer chain forming a hydrogel layer, covalently attached to electrode non-conductive surface (i.e. the polyimide).
Concerning 2-oxazoline-based hydrogels, in the first step, bromomethyl initiating groups will be introduced to the polyimide electrode substrate by plasma induced modification or by photochemical grafting using 4-azidophenyl group, as in the case of zwitterionic polymers. In the second step, cationic copolymerization of 2-oxazoline monomers with bifunctional crosslinkers will be induced by the surface-linked macroinitiator. This will lead to the achievement of covalently crosslinked hydrogels with biocompatible and protein-repellent properties that will be covalently attached to the electrode surface.
Task 5.3: Advanced prototype integration (SMANIA, All)
This task will address the integration of the different technologies towards the assembly of advanced neural interfaces, to be subsequently tested in vivo (during Task 6.2). SMANIA will coordinate this activity, which involves all partners and takes place from M10 to M11 and from 29 to M30. Different prototypes will be assembled. 12 prototypes (3 per electrode type) will be integrated in the first period (M10-M11) and other 12 prototypes will be delivered in the second period (M29-M30).