This fall, more than a third of new cars must, by federal mandate, be able to sense the difference between an adult occupant, a child and an empty seat. Airbags would then only inflate as much as needed. Weight and tension sensors under seats and in seatbelts are the first step, but Siemens, TRW and Motorola are developing lasers, 3-D cameras and electrical fields that can determine occupants' position as well as their size.
Five amazing, clean technologies that will set us free, in this month's energy-focused issue. Also: how to build a better bomb detector, the robotic toys that are raising your children, a human catapult, the world's smallest arcade, and much more.