A good wrist phone needs sound, so Gammel's team started with a micro-machined microphone 50 times smaller than that found in a typical cell phone. When a sound wave hits it, two thin silicon membranes bend, increasing the electric signal between them. Next, the team drastically reduced the size of the filter, which lets in the one radio frequency that the phone uses. Finally, there's the inductor, which listens for incoming calls. Gammel reduced it to a tiny loop of wire bending up from the surface of a silicon chip like a miniature taco shell.
There are still a lot of missing parts, some of which may not be available for a few years. And Bell Labs doesn't make commercial products, so someone else will have to put the pieces together. That's fine with Gammel. "The watch I wear is not even electric. It's a mechanical antique," he admits.


