Biomedical subjects

Wentai Liu

Publications and source records attributed to Wentai Liu.

3 recordsLinked to original sources

PubMed2005

Retinal prosthesis.

Retinal prostheses represent the best near-term hope for individuals with incurable, blinding diseases of the outer retina. On the basis of the electrical activation of nerves, prototype retinal prostheses have been tested in blind humans and have demonstrated the capability to elicit the sensation of light and to give test subjects the ability to detect motion. To improve the visual function in implant recipients, a more sophisticated device is required. Simulations suggest that 600-1000 pixels will be required to provide visual function such as face recognition and reading. State-of-the-art implantable stimulator technology cannot produce such a device, which mandates the advancement of the state of the art in areas such as analog microelectronics, wireless power and data transfer, packaging, and stimulating electrodes.

Animals↗

PubMed2003

Electronic visual prosthesis.

Retinitis pigmentosa (RP) and age-related macular degeneration (AMD) are incurable diseases that result in profound vision loss due to degeneration of the light sensing photoreceptors. However, the discovery that direct electrical stimulation of the retinal neurons creates visual sensation has inspired prosthetic devices aimed to restore useful vision in RP/AMD patients. The approach to one such electronic visual prosthesis is described in this article. The prosthesis consists of an external unit and an internal unit. The communication link has three components--power and data transfer from the external to the internal unit, and data transfer from the internal to the external unit. A novel method of integrating power transfer and back telemetry is described here. The goal is to design a stimulator chip with a small area with low power consumption. This chip, capable of stimulating 60 dedicated electrodes, is fabricated using AMI 1.2 microm process technology and the results are presented. Improvements in the design to increase the number of outputs to 1,000 have been discussed. The new circuit is aimed at increasing the circuit density, reducing power per stimulus, and meeting the requirements more closely than the previous designs. The results of the designed chip are presented.

Artificial Organs↗

PubMedDate not supplied

Retinal prosthesis for the blind.

Most of current concepts for a visual prosthesis are based on neuronal electrical stimulation at different locations along the visual pathways within the central nervous system. The different designs of visual prostheses are named according to their locations (i.e., cortical, optic nerve, subretinal, and epiretinal). Visual loss caused by outer retinal degeneration in diseases such as retinitis pigmentosa or age-related macular degeneration can be reversed by electrical stimulation of the retina or the optic nerve (retinal or optic nerve prostheses, respectively). On the other hand, visual loss caused by inner or whole thickness retinal diseases, eye loss, optic nerve diseases (tumors, ischemia, inflammatory processes etc.), or diseases of the central nervous system (not including diseases of the primary and secondary visual cortices) can be reversed by a cortical visual prosthesis. The intent of this article is to provide an overview of current and future concepts of retinal and optic nerve prostheses. This article will begin with general considerations that are related to all or most of visual prostheses and then concentrate on the retinal and optic nerve designs. The authors believe that the field has grown beyond the scope of a single article so cortical prostheses will be described only because of their direct effect on the concept and technical development of the other prostheses, and this will be done in a more general and historic perspective.

Blindness↗