Researchers at the University of Minnesota have 3D printed a light receptive array, consisting of silver particles and semiconducting polymers, on a glass hemispherical surface. The printed material can convert light to electricity, and the researchers hope that it could one day, with more research, end up serving as a bionic eye.
“Bionic eyes are usually thought of as science fiction, but now we are closer than ever using a multi-material 3D printer,” said Michael McAlpine, a researcher involved in the study. Printing electronics on a curved surface, such as that of a prosthetic eye, is challenging. This group of researchers used a custom 3D printer to overcome this issue, and successfully printed light-receptive material onto a glass hemispherical surface, as a proxy for the surface of a bionic eye.
Initially, the group printed a base ink of silver particles in a uniform layer. Despite the curvature of the surface, the ink didn’t run, and dried to form an array over the surface of the “eye”. Then, a second printed layer consisted of semiconducting polymers, which formed photodiodes that can convert light to electricity. The process was relatively rapid, taking approximately one hour.
The finished photodetectors achieved a 25% efficiency at converting light into electricity, which is comparable to microfabricated photodetectors. “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,” said McAlpine. “Plus, we can easily print a semiconducting device on a curved surface, and they can’t.”
The team plans to develop more advanced versions of the prototype, which have even more efficient photodetectors. Their next steps also involve developing a way to print on a soft material that could be implanted into a patient’s eye.