Flexoble Electrod Array for Retinal Stimulation

In the Work, ITO/PET (Indium Tin Oxide / Polyethylene Terephthalate) electrode structure which provides biocompatibility, mechanical stability and flexibility is fabricated. Flexible ITO/PET implantable electrode array for a retina has been developed. The electrode array is fabricated on a thin PET/ITO substrate and is encapsulated using, SU-8, an insulating material. PET substrate and SU-8 polymer make electrodes flexible so they could shape to contoured tissues. A layer of gold on the stimulation sites serves to reduce the electrode/tissue interface impedance. Prototypes of 4 ˣ 4 and 12ˣ6 electeode arrays are fabricated for primary and dense configuration of retina prosthesis respectively. The exposed electrode diameters are 125µm for primary and 100µm for dense micro electrode array. The stimulation sites of primary configuration were connected via 50µm interconnects with 50µm spacing. 40µm width traces with 15µm spacing connect sites to bonding pads in the other design. The verify the functionality of the micro fabricated electrodes, the electrochemical impedance spectroscopy is measured. The electrod/tissue impedance was 19.4KΩ at 1 KHz for 7854 µm2 area.

Keywords:

Retinal Prosthesis , Microelectrode Array , Stimulation Site , Flexibility , Biocompatibility , ITO/PET substrate , SU-8