Researchers at the University of Wisconsin-Madison have come up with a way to produce electricity from just about the most renewable source known to man -- his own breath. It's all thanks to a plastic microbelt developed by engineers Xudong Wang, Chengliang Sun and Jian Shi. Made of a material known as polyvinylidene fluoride (PVDF), this belt produces an electric charge whenever low-speed airflow passes over it and causes it to vibrate -- a result of that vaunted
