Design Challenge - No more kids accidentally left in cars

I think a timely design challenge would be some type of alarm to prevent drivers from inadvertently leaving young children in the car.

I think designers can put their heads together to work on this issue.

What would it take to send this design challenge out?

Sample Considerations:
• Keyfob alarm/indication/tactile reminder?
• Child seat sensor/alarm?
• Integration with Auto manufacturers, OnStar?
• Multiple sounding door chimes?
• Sensors (temperature, ignition, child presence)?
• Cell phone (timers, auto dialing, etc.)?
• Low cost, simple?