Basically, each room in the house would be equipped with an IR motion sensor. These sensors would then be linked to a hub somewhere in the house via bluetooth, X-10 or whatever which in turn can communicate with a carer. The sensors can trigger an alarm if no motion is monitored, meaning the client may have fallen or worse. This idea seems fairly straight forward and I'd be surprised if people haven't thought of it already but I can't seem to find any company online that actually markets...