Solvable problems

Tonight on the news I saw a story about a woman who had, completely by accident, left her sleeping toddler in a car for several hours. The child did not survive. The woman was absolutely devastated. I'm not an engineer, nor do I have any particular expertise with technology or mechanics, so I'm just brainstorming and speculating here. But it seems to me that with current technology, there might be a way to create some sort of reminder alarm that connects the car seat with the ignition. The alarm would need to be able to sense when a child was in the seat, and when the key was in the ignition, and thus go off when the seat was occupied and the key was removed from the ignition. The sensor on the car seat could maybe be triggered by weight, or turned on when the seat's restraints were fastened. Some sort of wireless technology could connect the seat and the ignition. Of course, the alarm would have to be something that would get the driver's attention without startling or waking up a sleeping child. I think the pieces probably exist, someone just needs to put them together into a functional system.