The camera can convert incident light into electric power. Source: Columbia University
An engineering team at Columbia University has developed what it calls the first fully self-powered camera, which could have huge implications for the surveillance industry down the line. The device measures incident light and can convert it into electric power.
The researchers say their prototype is capable of producing an image per second in well-lit, indoor settings.
“We are in the middle of a digital imaging revolution,” said Shree K. Nayar, director of Columbia Engineering’s Computer Vision Laboratory. “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.”
Nayar started working on his device after realizing that digital cameras and solar panels are made from similar components – despite serving different functions. Every digital camera boasts an image processor (a chip featuring millions of pixels). The photodiode, which is used in pixel sensors, plays an important role within the camera; it allows each pixel to measure the light intensity that falls on it.
Similarly, solar panels also have photodiodes, which are used to convert incident light into electric power. There is, however, a key difference in the way photodiodes are used in each device; the camera utilizes the photodiode in the photoconductive mode, while solar cells use them in the photovoltaic mode.
Creating an image sensor
For Nayar’s video camera, each pixel uses the photovoltaic mode of operation. He created an image sensor featuring 30x40 pixels using off-the-shelf materials. A 3D printer was used to create the prototype’s body.
With only a couple of transistors, the pixel design is quite basic. The pixels are used both to record the image, which is the first step in the image capture cycle, and to harvest energy. The camera constantly goes back and forth between these two functions and when it’s not capturing images it can generate power for other devices (such as a phone, for instance).
“A few different designs for image sensors that can harvest energy have been proposed in the past,” says Nayar. “However, our prototype is the first demonstration of a fully self-powered video camera. Even though we’ve used off-the-shelf components to demonstrate our design, our sensor architecture easily lends itself to a compact solid-state imaging chip. We believe our results are a significant step forward in developing an entirely new generation of cameras that can function for a very long duration – ideally, forever – without being externally powered.”
Source: Columbia Engineering