Stretchable micro-electrode array [for retinal prosthesis]

This paper focuses on the design considerations, fabrication processes, and preliminary testing of a retinal prosthesis that has the potential to aid in vision restoration to millions of blind patients. We are developing an implantable, stretchable micro-electrode array using polymer-based microfabrication techniques. The device will serve as the interface between an electronic imaging system and the human eye, directly stimulating retinal neurons via thin film conducting traces and electroplated electrodes. The metal features are embedded within a thin (~50 μm) substrate fabricated using poly (dimethylsiloxane) (PDMS), a biocompatible elastomeric material that has high oxygen permeability and low water permeability. The conformable nature of PDMS is critical for ensuring uniform contact with the curved surface of the retina. To fabricate the device, we developed unique processes for metalizing PDMS to produce robust traces capable of maintaining conductivity when stretched (strain = 7%, SD 1), and for selectively passivating the conductive elements. An in situ substrate curvature measurement taken while curing the PDMS revealed a tensile residual strain of 10%, explaining the stretchable nature of the thin metalized devices