This work was supported by the Air Force Office of Scientific Research Award # FA9550-09-1-0669- DOD35CAP. L.M. acknowl- edges fellowship support from the Department of Homeland Security (DHS). M.K. acknowledges funding from the Alexander von Humboldt Foundation. Electron microscopy and photolitho- graphy were performed at Harvard’s Center for Nanoscale Systems. Fabrication was partially supported by the National Science Foun- dation’s MRSEC Award #DMR-0820484. We thank Dr. Mughees Khan for nanofabrication of the blade surface used in this work.