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WP1 Metalisation

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Description

The objectives of this WP1 were to select an optimal silicone rubber metallization procedure and to make samples available for further processing or physical and biological tests.  The common goal of this project was to use this technology in the fabrication of a cuff electrode. In addition to the production of metal tracks, metal plots will have to be deposited in order to form appropriate electrode contacts.  In order to reduce the risks of the project, two metallization methods have been developed in parallel.

Achievements

Due to its weak surface energy, silicone rubber surface has to be activated before depositing a metallic coating.  Indeed, to ensure a good metal adhesion, it is necessary to introduce new surface chemical functionalities able to react with the metal.

In the first tested method, the surface activation treatment consists in cold a oxygen plasma treatment.  After the surface pre-treatment, a thin (~ 10nm) titanium layer is deposited by dc‑magnetron sputtering.  This intermediate layer is needed to ensure the adherence between the polymer substrate and the noble metal layer.  Afterwards, the noble metal layer (platinum, ~ 150 nm) is sputtered.  Finally, the deposition of thicker metal plots (few µm thick) used as electrodes, requires another deposition method i.e. an electroless deposition. 

The second method is based on the autocatalytic deposition of platinum on laser pre-irradiated silicone rubber sheets.  In more details, this technique consists of first irradiating silicone rubber sheets using a laser (YAG 266 nm or excimer 248 nm) to form tracks and contacts and second to immerse these sheets into a platinum autocatalytic bath where only the irradiated parts are metalized. This selective metallization can only occur when silicone rubber are pre-irradiated with a laser.