Solar-powered eye implants
A solar-powered implant could give sight to the blind, according to its developers at Stanford University, USA. Miniature photovoltaic (PV) cells are being used to power a chip placed behind the retina to process light and data through the eye to the brain.
‘Scientists have been trying for years to produce a practical retinal prosthesis for people afflicted by a progressive loss of photoreceptor cells’, explains Daniel Palanker, a Stanford Professor of Ophthalmology. ‘The problem with previous implants was finding a way to get power and data to a subretinal chip at the back of the eye.’
To achieve this, the Stanford team designed an array of mini solar devices that boost the amount of current sent to the still functional intermediate layers of the retina that perform the eye’s image processing and data compression. The system uses an external video camera that captures images, a pocket PC to process the video feed and a bright near-infrared LCD display built into video goggles, which transmits infrared light pulses to the PV device in the eye. The light pulses then produce electricity in the device, which transmits data through the eye so the brain can process it into a blurred picture.
The implant, which is coated with biocompatible iridium oxide, is three micrometres wide and 0.03mm thick, and includes three layers of flexible PV cells mounted with silicon posts.
The team used a microelectromechanical fabrication to connect the silicon flexures to the eye. The flexures enable the array to curve along with the natural shape of the retina but provide enough resistance (100 megohms) to isolate the electrical elements. This system is said to be capable of producing vision of 20/200, but researchers expect to achieve 20/100, creating a picture clear enough to recognise faces and read large print.Materials World Magazine, 01 Mar 2010
‘Scientists have been trying for years to produce a practical retinal prosthesis for people afflicted by a progressive loss of photoreceptor cells’, explains Daniel Palanker, a Stanford Professor of Ophthalmology. ‘The problem with previous implants was finding a way to get power and data to a subretinal chip at the back of the eye.’
To achieve this, the Stanford team designed an array of mini solar devices that boost the amount of current sent to the still functional intermediate layers of the retina that perform the eye’s image processing and data compression. The system uses an external video camera that captures images, a pocket PC to process the video feed and a bright near-infrared LCD display built into video goggles, which transmits infrared light pulses to the PV device in the eye. The light pulses then produce electricity in the device, which transmits data through the eye so the brain can process it into a blurred picture.
The implant, which is coated with biocompatible iridium oxide, is three micrometres wide and 0.03mm thick, and includes three layers of flexible PV cells mounted with silicon posts.
The team used a microelectromechanical fabrication to connect the silicon flexures to the eye. The flexures enable the array to curve along with the natural shape of the retina but provide enough resistance (100 megohms) to isolate the electrical elements. This system is said to be capable of producing vision of 20/200, but researchers expect to achieve 20/100, creating a picture clear enough to recognise faces and read large print.Materials World Magazine, 01 Mar 2010
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