An implantable silicon chip that faithfully mimics the neural circuitry of a real retina could lead to better bionic eyes for those with vision loss and would remove the need for a camera and external computer.

The chip, created by University of Pennsylvania and Stanford University researchers, measures 3.5 x 3.3 millimeters and contains 5760 silicon phototransistors, which take the place of light-sensitive neurons in a living retina. These are connected up to 3600 transistors, which mimic the nerve cells that process light information and pass it on to the brain for higher processing. There are 13 different types of transistor, each with slightly different performance, mimicking different types of actual nerve cells.