Google’s smart contact prototypes squeeze a glucose sensor, antenna, capacitor and chip between two contact lens layers, making a kind of electronics sandwich. A tiny hole on the eye side allows tear film, which contains glucose, to reach the sensor.

The integrated circuit is no larger than a piece of glitter, and its weight is undetectable on the tip of a finger. The sensor, which takes glucose readings twice a second, isn’t much bigger. And the antenna is thinner than a human hair.

The components sit on top of a thin plastic-like film that is made of a biocompatible material (Google doesn’t want to disclose exactly what material that is) that holds everything together like a fiberglass circuit board traditionally would.

Google’s smart lens broadcasts its readings through radio frequencies to an external monitoring device that a test subject carries with him or her. In turn, the device powers the mechanics of the lenses through those same radio frequencies.

Project lead Brian Otis mentioned that a later design might include a light source in the lens, which could indicate to the wearer whether glucose levels are high, medium or low — perhaps even when they close their eyes.

As Otis sees it, in some ways the smart contact lens is the flip side of Moore’s Law, where instead of adding capacity and speed to circuits, Google went small and low-power. The device still requires tens of thousands of transistors, but they are so tiny they can’t be seen.

“You can take a chip riding the freight train of Moore’s Law, with a number of transistors, and get rid of everything else — thin the chip down to make it as small as possible, try to get rid of all of the other external components that typically surround it, get rid of the rigid printed circuit board, and rethink the way that you put these systems together,” Otis said.

“That’s why this has been such an exciting project for me,” he added. “Being able to push those philosophies to the limit, while tackling something that could potentially be a huge benefit for people.”