Columbia University researchers have figured out an ingenious way to build a self-powered digital video camera . One that would never need to be recharged and could take a photo a second for an indefinite amount of time.
Shree K. Nayar, a professor of computer science at the university, came up with the idea of the self-powered camera by realizing how digital cameras and solar panels are alike. While they use light differently, they are built from the same components.
The university says, “At the heart of any digital camera is an image sensor, a chip with millions of pixels. The key enabling device in a pixel is the photodiode, which produces an electric current when exposed to light. This mechanism enables each pixel to measure the intensity of light falling on it. The same photodiode is also used in solar panels to convert incident light to electric power. The photodiode in a camera pixel is used in the photoconductive mode, while in a solar cell it is used in the photovoltaic model.”
Working with a team of engineers, Nayar built the device using off-the-shelf parts and a 3D-printed camera body. The homemade image sensor has 30×40 pixels with each pixel always operating in the photovoltaic mode. During an image capture cycle, the pixels work in two stages: first to record the image and then to harvest electricity from the light to charge the sensor’s batteries. While in use, it will continually go between the two stages, but when images don’t need to be captured, the camera can just harvest electricity and even be used to charge other devices.
The images produced are fairly grainy, but they do indeed prove that this technology is possible and the applications are practically endless.
“We are in the middle of a digital imaging revolution,” says Nayar, who directs the Computer Vision Laboratory at Columbia Engineering. “I think we have just seen the tip of the iceberg. Digital imaging is expected to enable many emerging fields including wearable devices, sensor networks, smart environments, personalized 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.”