[lidavidm]

Olympus and other cameras can do this with "pixel shift": it uses the stabilization mechanism to quickly move the sensor by 1 pixel.

https://en.wikipedia.org/wiki/Pixel_shift

EDIT: Sigma also has "Foveon" sensors that do not have the filter and instead stacks multiple sensors (for different wavelengths) at each pixel.

https://en.wikipedia.org/wiki/Foveon_X3_sensor