Optoelectronic retina without batteries
Photocells have become the basis of artificial retina
The work was published in the journal Nature Photonics (Mathieson et al., Photovoltaic retinal prosthesis with high pixel density).
The developed system consists of several components: special glasses, a laptop computer and the artificial retina itself. The implantable device is a set of miniature (about 70 microns) cells that carry photocells sensitive to near infrared light.
The image recorded by the miniature camera built into the glasses is simplified and prepared separately for each eye by a portable computer. Only contours stand out from a complex image. The result is projected onto the artificial retina. The infrared beam hitting the cell of the device causes it to turn on, which leads to the activation of nearby neurons. The brain perceives the activation of retinal neurons as the appearance of visible objects.
The scheme of the implant from the detailed description of the project on the website of Stanford University
(Restoration of Sight to the Blind: Optoelectronic Retinal Prosthesis) – VM.
In this case, the infrared beam is both an information transmitter and a power source for the operation of the artificial retina. According to the developers, this greatly simplifies its device. In cases where energy transfer using electromagnetic induction is used to power the artificial retina, this requires embedding bulky coils into the implant.
The developers tested the created device on healthy and damaged retinas of rats and showed that the transmitted energy is enough to activate neurons, despite the fact that the intensity of the infrared beam used is two orders of magnitude less than the maximum safe level. Scientists plan to test the device's performance on live rats, and then on volunteers.
Artificial retinas currently being developed are divided into two types according to the place of their implantation: those that are in front of, and those that are located under the retina. The device described in this article belongs to the latter type. They usually contain photocells to activate the neurons of the patient's retina. Their main disadvantage is low sensitivity – visible light is often not enough for the normal operation of solar cells. In this article, the authors solved this problem by activating solar cells not with natural light, but with an artificial infrared beam.
Portal "Eternal youth" http://vechnayamolodost.ru14.05.2012