Researchers at University of Minnesota in the US started with a hemispherical glass dome to show how they could overcome the challenge of printing electronics on a curved surface.
Using their custom-built 3D printer, they started with a base ink of silver particles.
The dispensed ink stayed in place and dried uniformly instead of running down the curved surface.
The researchers then used semiconducting polymer materials to print photodiodes, which convert light into electricity. The entire process takes about an hour.
“Bionic eyes are usually thought of as science fiction, but now we are closer than ever using a multimaterial 3D printer,” said Michael McAlpine, associate professor at University of Minnesota in the US.
The most surprising part of the process was the 25 per cent efficiency in converting the light into electricity they achieved with the fully 3D-printed semiconductors. “We have a long way to go to routinely print active electronics reliably, but our 3D-printed semiconductors are now starting to show that they could potentially rival the efficiency of semiconducting devices fabricated in microfabrication facilities,” McAlpine said.
“Plus, we can easily print a semiconducting device on a curved surface, and they can’t,” he said. McAlpine and his team received international attention a few years ago for printing a “bionic ear.” Since then, they have 3D printed life-like artificial organs for surgical practice, electronic fabric that could serve as “bionic skin,” electronics directly on a moving hand, and cells and scaffolds that could help people living with spinal cord injuries regain some function.
The next steps for the bionic eye are to create a prototype with more light receptors that are even more efficient. They would also like to find a way to print on a soft hemispherical material that can be implanted into a real eye.