Helical gold nanotube film as stretchable micro/nanoscale strain sensor

A micro/nanoscale strain sensor based on helical gold nanotube films (GNTFs) is proposed, which is prepared by magnetron sputtering using carbon nanocoils (CNCs) as templates. The gauge factor of the sensor reaches 5, while the stretch of it can achieve more than 10% owing to the helical geometries. The resistance increase of GNTFs with temperature decreasing from 300 to 4 K indicates a thermal activation tunneling model for electron transport. With thicknesses increasing from 16 to 32 nm, the GNTFs show a structural transition from discontinuous to quasi-continuous film. In this transition region, the conductive path of GNTFs increases rapidly, resulting in a rapid resistance decrease of CNC-GNTF composite structure. When a helical GNTF is stretched, the resistance is increased. The helical GNTFs in the transition region exhibit the highest response sensitivity, which owes to the special torsion-dominated strains of this helical structure to some extent. The unique helical morphology gives the sensor great stretchability and special electrical response. Choosing appropriate CNCs and GNTFs with suitable thickness, the helical GNTFs can be used as micro/nanostretchable strain sensors, stretchable electrodes or connects, resonators in micro/nanoelectromechanical system.