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Abstract
The aim of visual prostheses is to return a perception of sight for blind people. From the outset, designing a visual prosthesis system that minimizes platinum dissolution remains a challenge. Recently, laser surface modification was introduced to reduce platinum dissolution. This study will investigate the performance of laser-pattern for platinum electrodes, in particular structured laser interference patterning (SLIP), both in inorganic saline and biologically relevant solution. In this study, a new platinum electrode laser fabrication technique based on enamel was proposed, which can produce more accurate electrode exposure areas and a higher degree of control on surface morphology of microelectrodes. This new method describes the advantages of laser fabrication, which requires no clean room facilities and offers short design-to-prototype time. The feasibility of fabricating implantable electrodes with this method using medical grade enamel will require additional testing. An artificial suprachoroidal interstitial fluid (ASIF) preparation was further developed as a more appropriate test electrolyte for visual prostheses in vitro experiments. This artificial fluid was prepared by analysing residual solution on the surface of electrodes which were explanted from sheep suprachoroidal space. The extent of platinum dissolution occurring on laser-patterned electrodes stimulated at clinically-relevant levels in both Dulbecco’s phosphate buffered saline (DPBS) and ASIF was also quantified. Laser surface modification on electrodes minimised platinum dissolution during electrical stimulation and enhanced charge storage capacity of electrodes both in DPBS and ASIF. Furthermore, SLIP pattern showed the great improvement on the performance of electrodes, and that improvement was not simply related to the increase of electrode surface morphology variation but potentially because of the laser surface plasmon interference effect.