Rob Carter, 51, bombed out of premed before deciding to indulge his fascination with computers. His latest innovation combines his tech expertise with his early interest in health care: FedEx's SenseAware technology, launching in June, monitors the whereabouts of heart valves, knee implants, and other critically sensitive life-science shipments. "One of the basic needs we saw was a sensor-based logistics industry that wasn't solidifying as quickly as we thought it should," says Carter. Developing the system, which uses light and temperature signals to notify recipients if a package has been opened before it meets its intended destination, took him and his team three years. The FAA finally approved it for use on FedEx flights last year.