The elongation of free-standing one-dimensional (1D) functional nanostructures into lengths above the millimeter range has brought new practical applications as they combine the remarkable properties of nanostructured materials with macroscopic lengths. However, it remains a big challenge to prepare 1D silicon nanostructures, one of the most important 1D nanostructures, with lengths above the millimeter range. Here we report the unprecedented preparation of ultralong single-crystalline Si nanowires with length up to 2 cm, which can function as the smallest active material to facilitate the miniaturization of macroscopic devices. These ultralong Si nanowires with augmented flexibility are of emerging interest for flexible electronics. We also demonstrate the first single-nanowire-based wearable joint motion sensor with superior performance to reported systems, which just represents one example of novel devices that can be built from these nanowires. The preparation of ultralong Si nanowires will stimulate the fabrication and miniaturization of electric, optical, medical, and mechanical devices to impact the semiconductor industry and our daily life in the near future.
Keywords: Ultralong nanostructures; VLS; flexible electronics; silicon nanowires; strain sensors.