An electronically-controlled lens that could eventually function in an artificial eye is the latest invention to come out of Harvard School of Engineering and Applied Sciences.
The large-scale metalens, complete with an artificial muscle, is the initial step toward a sensory eye that could relay images to the human brain, according to the Harvard Gazette.
"This research combines breakthroughs in artificial muscle technology with metalens technology to create a tunable metalens that can change its focus in real time, just like the human eye," said Harvard graduate student and research co-author Alan She, adding that the future artificial eye could actually function better than a human eye.
"We go one step further to build the capability of dynamically correcting for aberrations such as astigmatism and image shift, which the human eye cannot naturally do."
The lens is made of metamaterial, a material engineered to have properties not found in natural substances, such as unique electromagnetic features.
Metalenses are very small, about the size of a piece of glitter, making them generally too small to function as an eye lens. However, scaling up the size of the lens was no easy task, as each expansion multiplied the already-information-dense nanomaterial.
To meet the challenge, the team succeeded in shrinking the file size to make it workable with the fabricated integrated circuits system.
The team then worked to bind the enlarged metalens to the artificial muscle, which consists of transparent dialectic elastomer actuators.
Elastomers stretch when an electric voltage is applied, allowing the lens to change size to focus, perform image shift and correct aberrations found in a human eye, such as astigmatism.
The complete, perfectly flat metalens is a mere 30 microns thick.
"All optical systems with multiple components — from cameras to microscopes and telescopes — have slight misalignments or mechanical stresses on their components, depending on the way they were built and their current environment, that will always cause small amounts of astigmatism and other aberrations, which could be corrected by an adaptive optical element," said She.
"Because the adaptive metalens is flat, you can correct those aberrations and integrate different optical capabilities onto a single plane of control."
The team still needs to work out a few kinks in the project, including reducing required voltage and improve lens functionality.
But the invention marks an important step toward the creation of a fully-functional artificial eye that might even work better than a real one.
