Julian Preston-Powers of Brighton says it could be accomplished with simple modifications, NewScientist.com reported Wednesday.
"The proximity sensors that currently exist in virtually all cars dating back to 10 years in age are of sufficient technology to roll all windows down 2 or so inches in a car that self-detects motion," he says.
The sensors could trigger a car's headlights to flash to alert people near the car, he said.
Current sensors used as part of intruder detection systems are usually set to trigger only when large movements are detected, but could be modified to have an alternate setting sensitive enough to detect the subtle movement of a baby sleeping or a snoozing dog when the cabin is sealed, Preston-Power said.
"The Internet is littered with horror stories of parents forgetting one of their children in the car and returning to find the child dead," he said. "This can happen when outdoor temperatures are as low as 21 degrees C (70 degrees Fahrenheit.)"
Preston-Powers said he wants to put his solution into the public domain rather than patenting it.
"If it saves just one child or dog from dying in a car per year, then it was worth it," he said.