Select your localized edition:

Close ×

More Ways to Connect

Discover one of our 28 local entrepreneurial communities »

Be the first to know as we launch in new countries and markets around the globe.

Interested in bringing MIT Technology Review to your local market?

MIT Technology ReviewMIT Technology Review - logo

 

Unsupported browser: Your browser does not meet modern web standards. See how it scores »

Today’s digital cameras are remarkable devices, but even the most advanced cameras lack the simplicity and quality of the human eye. Now, researchers at the University of Illinois at Urbana-Champaign have built a spherical camera that follows the form and function of a human eye by building a circuit onto a curved surface.

The curved sensor has properties that are found in eyes, such as a wide field of view, that can’t be produced in digital cameras without a lot of complexity, says John Rogers, lead researcher on the project. “One of the most prominent [features of the human eye] is that the detector surface of the retina is not planar like the digital chip in a camera,” he says. “The consequence of that is [that] the optics are well suited to forming high-quality images even with simple imaging elements, such as the single lens of the cornea.”

Electronic devices have been, for the most part, built on rigid, flat chips. But over the past decade, engineers have moved beyond stiff chips and built circuits on bendable sheets. More recently, researchers have gone a step beyond simple bendable electronics and put high-quality silicon circuits on stretchable, rubberlike surfaces. The advantage of a stretchable circuit, says Rogers, is that it can conform over curvy surfaces, whereas bendable devices can’t.

The key to the spherical camera is a sensor array that can withstand a curve of about 50 percent of its original shape without breaking, allowing it to be removed from the stiff wafer on which it was originally fabricated and transferred to a rubberlike surface. “Doing that requires more than just making the detector flexible,” says Rogers. “You can’t just wrap a sphere with a sheet of paper. You need stretchability in order to do a geometry transformation.”

The array, which consists of a collection of tiny squares of silicon photodetectors connected by thin ribbons of polymer and metal, is initially fabricated on a silicon wafer. It is then removed from the wafer with a chemical process and transferred to a piece of rubberlike material that was previously formed into a hemisphere shape. At the time of transfer, the rubber hemisphere is stretched out flat. Once the array has been successfully adhered to the rubber, the hemisphere is relaxed into its natural curved shape.

Because the ribbons that connect the tiny islands of silicon are so thin, they are able to bend easily without breaking, Rogers says. If two of the silicon squares are pressed closer together, the ribbons buckle, forming a bridge. “They can accommodate strain without inducing any stretching in the silicon,” he says.

To complete the camera, the sensor array is connected to a circuit board that connects to a computer that controls the camera. The array is capped with a globelike cover fitted with a lens. In this setup, the sensor array mimics the retina of a human eye while the lens mimics the cornea.

2 comments. Share your thoughts »

Credits: Beckman Institute, University of Illinois

Tagged: Computing, digital camera, artificial retina, stretchable silicon

Reprints and Permissions | Send feedback to the editor

From the Archives

Close

Introducing MIT Technology Review Insider.

Already a Magazine subscriber?

You're automatically an Insider. It's easy to activate or upgrade your account.

Activate Your Account

Become an Insider

It's the new way to subscribe. Get even more of the tech news, research, and discoveries you crave.

Sign Up

Learn More

Find out why MIT Technology Review Insider is for you and explore your options.

Show Me