High resolution photovoltaic retinal prosthesis with three-dimensional neural interface
Abstract/Contents
- Abstract
- The number of electronic implants for restoration of various neural functions is rapidly growing. They include such highly successful systems as cochlear implants for restoration of hearing and deep brain stimulators for reducing the symptoms of Parkinson's disease. Retinal degenerative diseases lead to loss of photoreceptors, while neurons in the inner retinal layers are largely preserved. Retinal prostheses seek to restore sight by reintroducing visual information via electrical stimulation of the surviving neurons in the retina. Most retinal prostheses are powered through inductive coils, requiring complex surgery. At Stanford, our group developed a photovoltaic approach to retinal prosthetics, where silicon photodiodes in each pixel of the sub-retinal array convert pulsed near-infrared illumination projected from video goggles into an electric current to stimulate the nearby neurons. This work presents the design and fabrication process of the implantable photovoltaic arrays, and demonstrates their performance in vitro, as well as the results of preclinical testing in vivo. In particular, we have shown that spatial resolution of prosthetic vision with 70 um pixels in rodents is limited by the pixel pitch, and stimulation thresholds are much lower than the ocular safety limits. Based on this success, we developed a new process that enabled fabrication of pixels as small as 40 um in size. To improve proximity between the electrodes and neurons, we developed three-dimensional pillar electrodes, and found their optimal height for integration with the retina during chronic implantation. We also developed a fabrication process for incorporating these pillar electrodes into photovoltaic arrays. During early in vivo experiments, we observed significant degradation of the retinal implants. To prevent this, we developed a process of using a plasma-enhanced chemical vapor deposited SiC films compatible with the rest of the photovoltaic array fabrication. This coating exhibited excellent stability during accelerated aging tests in vitro as well as during chronic implantation in vivo. The final chapter of this thesis provides outlook toward future directions for advancement and testing of this novel retinal prosthetic technology.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2018 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Lei, Xin |
|---|---|
| Associated with | Stanford University, Department of Electrical Engineering. |
| Primary advisor | Harris, J. S. (James Stewart), 1942- |
| Thesis advisor | Harris, J. S. (James Stewart), 1942- |
| Thesis advisor | Kamins, Theodore I |
| Thesis advisor | Palanker, Daniel |
| Advisor | Kamins, Theodore I |
| Advisor | Palanker, Daniel |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Xin Lei. |
|---|---|
| Note | Submitted to the Department of Electrical Engineering. |
| Thesis | Thesis (Ph.D.)--Stanford University, 2018. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2018 by Xin Lei
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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