While we may think that it's only irresponsible, negligent people who leave infants or pets in hot cars, it can also sometimes happen to preoccupied folks who simply forget that they've got an extra passenger on board. Payton's Charm is designed to alert them, should that happen.

Developed by Alabama-based VI Enterprises, Payton's Charm is named after a young girl who passed away from heat stroke after being forgotten in the family car by her father. It's intended to be permanently plugged into the vehicle's power socket, although it can also run for up to a month on one charge of its battery.

An integrated accelerometer detects when the car has stopped moving, at which point the device begins monitoring the air temperature within the vehicle, along with its carbon dioxide content. If the CO2 levels indicate that a child or pet is present (and exhaling) inside the vehicle, and if the temperature climbs dangerously high, Payton's Charm sends a text alert to the user's smartphone.

If the user doesn't respond to that text, a second alert is sent to another predetermined phone number. Should that message also go unacknowledged, the device sends an alert to emergency services, with the vehicle's GPS coordinates. A message is also sent to the user if the battery is getting low.

Payton's Charm is currently the subject of a Kickstarter campaign, where a pledge of US$201 will get you a unit – assuming it reaches production, that is. One year of cellular service for the device is included in that price, after which a "low monthly fee" will be required. The planned retail price is $349.

Prospective backers might also want to check out the ChildMinder system, which causes a key-ring alarm to sound if drivers walk more than 15 feet (4.6 m) away from a pressure-sensitive pad upon which their backseat baby is sitting.

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