Single-Nanowire strain sensors fabricated by nanoskiving

This article describes the fabrication of single-nanowire strain sensors by thin sectioning of gold films with an ultramicrotome-i.e., “nanoskiving.” The nanowire sensors are transferred to various substrates from the water bath on which they float after sectioning. The electrical response of these single nanowires to mechanical strain is investigated, with the lowest detectable strain determined to be 1.6 × 10−5 with a repeatable response to strains as high as 7 × 10−4. The sensors are shown to have an enhanced sensitivity with a gauge factor of 3.1 on average, but as high as 9.5 in the low strain regime (ε ∼ 1 × 10−5). Conventional thin films of gold of the same height as the nanowires are used as controls, and exhibit inferior sensitivity. The practicality of this sensor is investigated by transferring a single nanowire to polyimide tape, and placing the sensor on the wrist to monitor the pulse pressure waveform from the radial artery. The nanowires are fabricated with simple tools and require no lithography. Moreover, the sensors can be “manufactured” efficiently, as each consecutive section of the film is a quasi copy of the previous nanowire. The simple fabrication of these nanowires, along with the compatibility with flexible substrates, offers possibilities in developing new kinds of devices for biomedical applications and structural health monitoring.