A article in the journal Nature has reported that scientists from Hong Kong and the U.S. have taken a big step toward development of a true bionic eye, more precisely called a “biomimetic electrochemical eye”.
Attempts that set it apart from other such efforts, such as the Argus 2 device, are its similarity to many of the components of the human eye:
- At its core is the high-density array of photosensors that mimics the human retina’s photoreceptor cells.
- Attached to each photosensor are tiny flexible wires which transmit light signals to external circuitry for processing. These mimic the nerve fibers that connect the human eye to the brain.
- A lens and an artificial iris are positioned at the front of the device, and a spherical shell covers the components, forming the “eyeball”. The chamber within the shell is lined with a tungsten film and filled with an ionic liquid that supports the electrochemical process. This is similar to the vitreous fluid in the human eye, but it serves a different purpose.
The device, due to its spherical shape, allows a field of view of 100°, which is close to that of the human eye. Other sensory capabilities that compare favorably are:
- Sensitivity to a wide range of light intensities
- Quick photoreceptor recovery time
- High density of photosensors possible, due to the device’s curved surface
This is promising research, which has yet to see resolution of certain issues:
- The photosensor array output is still too small at only 100 pixels.
- Fabrication costs are very high.
- The diameter of the wires needs to be greatly reduced from ~700 to only a few micrometres.
- The functional lifetime of the components has yet to be determined.
- Further optimization of the ionic-liquid composition is needed.
Application to robotics will likely be the first use for this device, but the researchers are hopeful that it might be ready for humans within a decade.
SOURCE: Nature 581, 264-265 (2020) doi: 10.1038/d41586-020-01420-7