Nanospring pressure sensors grown by glancing angle deposition

Arrays of Cr zigzag nanosprings and slanted nanorods, 15-55 nm and 40-80-nm-wide, respectively, were grown on SiO2/Si substrates by glancing angle deposition. The arrays exhibit a reversible change in resistivity upon loading and unloading, by 50% for nanosprings and 5% for nanorods, indicating their potential as pressure sensors. The resistivity drop is due to a compression of nanosprings (by a measured 19% for an applied external force of 10(-10) N per spring), which causes them to physically touch their neighbors, providing a path for electric current to flow between nanosprings. Repeated loading and unloading at large loads (> or =1 MPa) results in irreversible plastic deformation and a degradation of the pressure sensitivity.