New sight

Bioengineers at the University of Minnesota have 3D-printed a network of light receptors on a hemisphere about the size of the front half of a human eyeball.

Using a glass dome as a base, the scientists began by covering the surface with a layer of ink containing silver particles. The ink’s consistency held the silver in place instead of letting it run off the rounded surface. Next, the team used semiconducting polymers to lay down a film of photodiodes, which turn light into electrical pulses.

The printing process, which takes about an hour, results in an “eye” that reaches 25 percent efficiency in converting light into electricity, which – with training for the human wearer – could be translated by the brain into contrasts of light and dark or perhaps vague images.

The team now is figuring out how to print photodiodes on a soft surface while making the receptors more efficient and, even more daunting, connecting the artificial eye to the brain’s visual processing center.

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