It makes perfect sense. The sensors that capture images for a digital camera and the sensors that convert light into electricity for a solar cell rely on the same technology. So why not build a device with a sensor that does both, and create a self-powered video camera? Some clever researchers did just that.
A team led by computer science professor Shree Nayar at Columbia University, New York, recently built the world’s first self-powered video camera. The resolution isn’t great as it can produce one image per second in a well-lit space, but it can theoretically record video forever.
Built from off-the-shelf parts, the new forever cam takes advantage of a photodiode’s capability to be used in both photoconductive (i.e. digital camera) and photovoltaic (i.e. solar cell) modes. Nayar’s prototype camera has a sensor with 30-by-40 pixels, each of which toggles back and forth between capture and charge. After measuring the intensity of the light coming through the lens in photoconductive mode, the sensor converts the light into electricity in photovoltaic mode. It looks pretty unassuming, but the possibilities for such an invention are nothing short of thrilling.
“We are in the middle of a digital imaging revolution,” says Nayar, who’s also the director of the Computer Vision Laboratory at Columbia Engineering. “Digital imaging is expected to enable many emerging fields including wearable devices, sensor networks, smart environments, personalised medicine, and the internet of things. A camera that can function as an untethered device forever — without any external power supply — would be incredibly useful.”