There is a device That does just that...............I’ll look for it...............
Here it is:
http://www.huffingtonpost.com/2015/06/02/hot-car-death-prevention_n_7455532.html
excerpt if allowed: """"Infant SOS has sensors that can detect if the car is parked with the baby still in the seat, the Rice University news site explains. After 30 seconds, the device will light up and sound an alarm. If the child has not been removed from the seat after five minutes, it will send up to 10 text message alerts to pre-programmed contacts, such as parents, other relatives, and emergency responders.""""