An ambitious neurotechnology program has been started in Germany in 1995, in the long run aiming at the realization of visual prostheses for blind people. A broad technological approach has been chosen which besides crystalline silicon microelectronics also involves amorphous silicon photodiodes for subretinal implantation, because thin film technology may be able to offer better solutions to some of the complex problems. Special topics we report on here include the development of low temperature deposition techniques for enabling the use of flexible plastic or bio-degradable substrate foils, the study of protective and bio-compatible coatings, as well as novel contacting and energy supply schemes. The key issue for stimulating retina cells by the use of technically generated photocurrents is an optimum capacitive coupling to these cells. For this purpose we study several contact layers (p-doped a-Si:H, microcrystalline Si, metal-induced crystallization) which provide high perpendicular but at the same time low lateral conductivity, thereby greatly reducing parasitic losses to the surrounding tissue. The photovoltaic mode of operation of the implanted photodiodes may be limited due to shortcomings in the charge transfer to the nerve cells, in which case additional infrared energy has to be coupled into the devices. Local light-induced stimulation can then be realised by using an a-Si:H i-layer as a photoresistor on top of the IR-sensitive solar cell.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.