Tiny camera can power itself and other devices

16 Apr 2015 | Author: | No comments yet »

Battery-Free Video Cam Grabs Pix—and Power—from Same Light [Video].

The world’s first self-powered video camera that runs without a battery and can produce an image each second has been developed by researchers led by an Indian-origin scientist. To develop the prototype camera, researchers designed a pixel that can not only measure incident light but also convert the incident light into electric power. “We are in the middle of a digital imaging revolution,” said Shree K Nayar, TC Chang Professor of Computer Science at the Columbia University, who led the study. “I think we have just seen the tip of the iceberg. By leveraging the technology that powers both digital imaging and solar panels, they’ve made a prototype model that draws energy from the ambient light in a well-lit room. A man changes facial expressions before moving his head up and down then side-to-side in a clip that looks a bit like a moving daguerreotype captured more than a century and a half ago.

Digital imaging is expected to enable many emerging fields including wearable devices, sensor networks, smart environments, personalised medicine, and the Internet of Things. The camera used to capture this head shot is cutting edge, however, using a new light-powered technology, which could lead to battery-free cameras that never shut down. The camera, which is made from off-the-shelf parts and will be presented next week at the International Conference on Computational Photography, doesn’t take especially sharp pictures.

The image sensor in a digital camera has millions of pixels, each of which functions as a photodiode, producing an electric current when exposed to light. That concept includes combining a camera image sensor’s ability to collect and measure light with a photovoltaic cell’s capacity to convert some of that light into energy.

But in this camera, the photodiodes cycle back and forth between the image-taking mode and an energy-harvesting mode, in which the current instead charges the battery. This means that if the camera is in a bright area, it can continuously take a photo every second, indefinitely, without ever needing an external charge. Nayar, working with research engineer Daniel Sims, and consultant Mikhail Fridberg of the consultancy firm ADSP Consulting used off-the-shelf components to fabricate an image sensor with 30×40 pixels. As of now, the camera — with housing extruded from a 3-D printer, by the way — can only take low-resolution images at a rate of about one per second. Nayar’s prototype camera does not need a battery but instead uses a supercapacitor that is continuously charged by energy harvested from the image sensor’s pixels.

It could perhaps be part of an array of face-recognizing security cameras, for instance, or a series of cameras that sense when someone’s in the room to adjust the heating or lighting accordingly. The current iteration of the camera can capture black-and-white 30-by-40-pixel images each second over an indefinite period of time for a scene that is about 300 lux in brightness. That may be low resolution but it proves the concept’s feasibility, says Nayar, who is also director of the Columbia School of Engineering’s Computer Vision Laboratory.

The camera could be installed as a surveillance device and function even during prolonged periods of darkness by storing and using excess power harvested in the daytime to generate images at night. A compact camera equipped with a solid-state version of the self-powered image sensor would be able to produce at least a 200-by-200-pixel image per second, Nayar adds. With continued improvements in resolution such a camera could prove useful in smartphones and wearable devices, given their poor battery life, and might eventually even be used to recharge the battery when not taking video.

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