Mechanical engineer Amy Smith's approach to problem-solving in developing nations is refreshingly common-sense: Invent cheap, low-tech devices that use local resources, so communities can reproduce her efforts and ultimately help themselves. Smith, working with her students at MIT's D-Lab, has come up with several useful tools, including an incubator that stays warm without electricity, a simple grain mill, and a tool that converts farm waste into cleaner-burning charcoal.

The inventions have earned Smith three prestigious prizes: the B.F. Goodrich Collegiate Inventors Award, the MIT-Lemelson Prize, and a MacArthur "genius" grant. Her course, "Design for Developing Countries," is a pioneer in bringing humanitarian design into the curriculum of major institutions. Going forward, the former Peace Corps volunteer strives to do much more, bringing her inventiveness and boundless energy to bear on some of the world's most persistent problems.