Jason Koebler writes: Researchers at Columbia University have designed a fully electric digital camera that powers itself using ambient light. Put in a well-lit room, it would work indefinitely. The camera's image sensor does double duty. It measures the light needed to make the photograph, and it also takes excess light and uses it to power a capacitor (it has no battery) that runs the camera (PDF). The research team says the technology can be used to create self-powered cameras that can live on the internet of things.