What is hard about consent for implants scattered through the brain in hundreds? · Grey Matter

Neural dust and neurograins have so far been tested only in animals, so this is a question asked ahead of time.

What is hard about consent for implants scattered through the brain in hundreds?

Neural dust and neurograins have so far been tested only in animals, so this is a question asked ahead of time. A single array can be removed if it fails or if the person changes their mind, while hundreds of grain-sized motes spread over the cortex would be hard to find, retrieve or switch off individually. Consent for such a system would have to cover removal and long-term support in advance, the point that reviews of neural device trials already make about post-trial responsibilities for ordinary implants.