Canon is one of the relatively few manufacturers that develops its own sensors. This means that they're in a great position to create new sensors with new capabilities, and that's just what they've done with their new 35mm Full Frame CMOS sensor for video capture
Although we don't know the full resolution of the sensor, it is described as having (relatively) gigantic pixels that although they're only 19 microns across, are 7.5 times the surface area of the pixels in Canon's own EOS 1D X - a top-of-the-range video-capable DSLR.
Pixel size is the key to sensitivity as the larger the pixels, the more photons (particles of light) they can capture - and the more they capture, the better the chance of distinguishing a given pixel's output from noise.
Very little light
Apparently the sensor is capable of working even in as little as 0.03 lux of illumination, which, Canon tells us, is approximately the brightness of a crescent moon. This is a level of light in which even the human eye has difficulty in perceiving objects.
We don't have any information about when this sensor might be available or what type of camera it might be used in, but we suspect that it is more likely to be security than cinematography. We would love to be proved wrong, though!
Here's a Canon-made video showing the capabilities of this new sensor.