This volume presents papers on the topics covered at the National Academy of Engineering's 2015 US Frontiers of Engineering Symposium. Every year the symposium brings together 100 outstanding young leaders in engineering to share their cutting-edge research and innovations in selected areas. The 2015 symposium was held September 9-11 at the Arnold and Mabel Beckman center in Irvine, California. The intent of this book is to highlight innovative developments in engineering research and technical work.