Time has come when cameras will power itself. With the help of out-of-the-box technology new species of cameras are born. But will it change everything?Â
What if the cameras can run without any external power forever? Well, itâ€™s going to be true as a research team led by Shree K. Nayar, T.C. Chang Professor of Computer Science at Columbia Engineering, has invented a one-of-its-type camera which is the first to be fully self-powered.Â They designed a pixel that can not only measure incident light but also convert the incident light into electric power.
â€œWe are in the middle of a digital imaging revolution,â€ says Nayar, who directs the Computer Vision Laboratory at Columbia Engineering. He notes that in the last year alone, approximately two billion cameras of various types were sold worldwide. â€œI 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, personalised medicine, and the Internet of Things. A camera that can function as an untethered device foreverâ€”without any external power supplyâ€”would be incredibly useful.â€
The team led by Nayar realised that though digital cameras and solar panels have different purposes but both are made by the same components. 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 mode.
The camera works in a very interesting way. The pixel design is very simple, and uses just two transistors. During each image capture cycle, the pixels are used first to record and read out the image and then to harvest energy and charge the sensor’s power supplyâ€”the image sensor continuously toggles between image capture and power harvesting modes. When the camera is not used to capture images, it can be used to generate power for other devices, such as a phone or a watch.
By Rohan Pal