The device is a sensor, and it represents some of the core technology of MC10, a startup that makes flexible electronics. Ghaffari, cofounder and director of advanced technology at the company, isn't at liberty to tell me what, exactly, it senses. It could be temperature, muscle activity, or heart rate.
The sensor's counterpart is another rectangle of silicone. This one encases more traditional semiconductor chips, each about half the size of your pinky nail. Rather than being soldered to a brittle green board that's etched with interconnects, the chips are linked by what appear to be the same wavy, bendable wires. It's not as flexible as the passive sensor because of the chips, but it's still supple enough to bend around my finger. It's the brains of the system, Ghaffari tells me. It receives data from the sensor and then processes, stores, and passes on that information.