Notes:

Research supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering under Award #DE-SC0005247 (fabrication of HAR structures) and by the U.S. Army Research Office Multi- disciplinary University Research Initiative under Award #W911NF-04-1-0476 (reinforced structures). We thank Profes- sor Theodore Betley for the use of equipment, Dr. Alison Grinthal for helpful comments, and Dr. James C. Weaver for graphic artwork. This work was carried out in part through the use of MIT’s Microsystems Technology Laboratories and Har- vard’s Center for Nanoscale Systems (CNS).