In reply to Tom Valentine:
When my company was making cameras (for phones) we'd clean the sensors in the lab with a very fine paintbrush. Am I right in thinking though that bigger digital cameras have the silicon enclosed in a package with a glass lid? We were cleaning the actual pixel array.
If so you can be a bit more coarse because the dust is further away from the pixel and so you only see much bigger pieces of dirt. Even so, we found that a jet of air entrapped dust from the surroundings and blasted it onto the surface. Again if the surface is dry *and uncoated* this may not matter as the dirt probably won't stick.